Everything you ever wanted to know about solar panels for domestic power, but were afraid to ask: How to design & build your own domestic free energy solution

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Everything you ever wanted to know about solar panels for domestic power, but were afraid to ask.

  How to design & build your own domestic free energy solution

  By

  P Xavier

  Copyright © 2018

Introduction

    HAVING READ A NUMBER of books that claim to teach the reader how to build/install a PV/wind turbine installation, it became plainly obvious that they all fell into two camps. The first were written by science boffins & are packed with PhD level scientific formulae, which is way beyond the needs or ability of most DIYers. The second set was so brief & contained so little information that they were basically pamphlets padded out with useless & sometimes dangerous information. Neither of these can be of use to the average person. This book is therefore aimed at everyone & imparts practical information to anyone who wishes to learn about the practicalities & economics of installing, running & maintaining a home photovoltaic system. It’s not a guide for idiots, but a useful & practical guide for everyone.

  This book contains the sections that are relevant to photovoltaic’s from the book ‘DIY home energy solutions’ by the same author, where photovoltaic systems, wind turbine energy generating systems, back-up electricity systems, solar water heating, ground sourced hot water & also light tubes are covered in detail. Each of those topic areas have been arranged into three broad groups. Design, installation & maintenance. Therefore, the reader should become competent in designing, constructing & running a system that is suitable for their own unique & individual needs. Both here & in ‘DIY home energy solutions’ all areas have been laid out in plain & simple English, allowing the concepts to be within anyone’s grasp, regardless of their academic ability.

 

Table of Contents

       Introduction      Table of contents      Notes      Chapter 1 Wholesale energy use & price      Chapter 2 The components used in every system      Chapter 3 Some notes on electricity      Chapter 4 Photovoltaic cells      Chapter 5 System enhancements      Chapter 6 Legislation in the UK      Chapter 7 The system design      Chapter 8 Maintenance      Chapter 9 Using a calculator to do the maths      Chapter 10 Easing the installation      Chapter 11 Obtaining finance, grants & mortgages      Table of illustrations      About the author

Notes

    THIS WORK IS BY THE author & as such, all copyright belongs to the author. You are not permitted to copy any text or images without the authors express permission.

  Some of the images in this book are created by the book’s author, others are either in the public domain or individually credited to their respective creator &/or copyright owner. Any other images are from sources where they are copyright free.

  This work is fully referenced to aid the reader in any future studies. That being said, internet references have been provided to aid study as most individuals do not have huge libraries at their disposal. It is far easier to research material online than to go through the expense of ordering specific books at a public lending library.

Chapter 1 - Wholesale energy use & price

    EVERYONE & EVERYTHING in the developed world needs & uses electrical energy. Every home has electrical appliances that use electricity; therefore every household faces a sizeable annual bill for their energy use.

  No doubt, most households have washing machines, fridge freezers, televisions, radios, computers, phones, DVD players, satellite receivers, hi-fi’s, microwave ovens, alarm clocks, lighting, heating. The list goes on & on. Yet, using each & every one of these appliances costs money to run & this cost is set to rise year on year as fossil fuels are slowly depleted & demand for electricity rises.

  Whilst demand for fossil fuels increases, so too will the cost. It is a simple case of demand outstripping supply which causes this monetary increase in costs.

  In the UK, the ‘National Grid’ predicts the cost of electricity to double by 2035 & gas to rise by 33% over the same time period. This is due to various factors, depletion of fossil fuels, governmental ‘green energy incentives’, lack of investment & most telling, the fact that by 2035, the UK is predicted to need to import 90% of its energy In addition, the US Energy Information Administration (EIA) also predicts an increase of 48% in total world energy demand by

 

The cost of obtaining energy has also risen 20% since 2009 & will clearly continue to increase; it therefore makes fiscal sense for all households to source as much energy as possible from cheaper alternatives. In addition to rising prices, the likelihood of future power cuts also increases dramatically. The UK’s Big Infrastructure Group (BIG) has warned that in the UK, the spare capacity of electrical energy that was ready to be delivered to consumers has fallen sharply in recent years. In 2011 - 2012 it was 17%, whilst in 2016 - 2017 it had fallen to 1%, therefore increasing the likelihood of BIG are not alone in predicting blackouts in the UK, the Institute of Mechanical Engineers predict that the UK will only have half the energy it needs by 2025 & they have also stated that “The UK is facing an electricity supply

  Since these predictions were made, both the UK & the EEC have announced that they intend to legislate to outlaw the sale of all new diesel & petrol vehicles by The Green Alliance has stated that the UK grid is not ready for the anticipated demand that electric vehicles will place on the grid & that blackouts will occur as a result because it takes the same amount of electricity that an average household uses in three days to charge one electric car They add that by 2025, 700,000 UK consumers will be experiencing blackouts due to this level of demand & also because of damage caused by increased levels of strain on the UK network. The UK electricity network was never designed to cope with these rising levels of predicted loads.

  Luckily, the green energy brigade has been busy developing viable solutions for the energy market. Photovoltaic cells have halved in cost since 2008 & seen an overall 100% reduction in price since In that time battery technology has also increased whilst the costs have decreased. The cost of batteries are predicted to continue to reduce in cost whilst the costs

of fossil fuels It is predicted that there should be a further 70% decrease in battery costs by 2050. There are many energy companies currently researching battery technology which is being funded by car manufacturers, mobile phone companies & many others. Therefore it can be clearly seen that whilst there will be an incremental cost increase on domestic electricity, the cost of renewable energy solutions are set to plummet.  The sun & wind are currently free resources. They will remain to be a free resource until the government decides to levy a tax on them. Until that time, these free energy sources should be exploited to the fullest.

  Therefore, the next logical step would be to look at the individual components that make up the installations that have the potential to save every household real money & thereby act as an investment, saving money for many years.

Chapter 2 - The components used in every system

    ALL INSTALLATIONS FOLLOW the same basic design principles as they are all made from the same basic components & operate in the same way. The only difference between any given system is the size & complexity of the individual elements. For instance, one system may have 20 batteries, another 200. One may have 4 photovoltaic panels, another may have 40. One may store energy on site to be used by the homeowner; another may opt to sell the electricity directly to the ‘National Grid’. There is no single correct solution to any given installation, but there are always better options to consider when undertaking the design. Cost for most will be a major factor when selecting individual components as these systems are an expensive investment. However, as previously stated, the costs are predicted to reduce significantly over the coming years.

  The concept in a nutshell

  EVERY SYSTEM COLLECTS energy, transforms it into a useable form & then makes it available for the user. None of these systems create electricity; they just transform one form of energy into another (solar energy & kinetic energy into electricity). This is all due to one fundamental law of nature: energy cannot be destroyed, but it can move from one form to another. This is a system that everyone is familiar with. For instance, as a tree grows it collects solar energy & converts it into sugar to fuel its life systems. It also stores some of that energy within its

trunk, branches & leaves. It has transformed solar energy into a form of energy that is more useful for it to use. We also can convert it into a form of energy that is more useful to us by simply burning the tree, thereby transforming the energy that the tree has stored into heat energy & a little back into light energy.

  Another example could be: plants harness solar energy & convert it into sugar to fuel its life systems. It also stores some of that energy within its self, animals (including humans) eat the plants & use what the plants have made, to fuel themselves. It’s not magic; it is just harnessing what nature does for our own benefit. Nature has been doing it for millions of years as it is so efficient. Harnessing solar & kinetic energy (solar & wind power) is just another method that we can harness for our needs.

  The system components

  AS STATED all systems consist of the same basic components. They are as follows:

  Collection elements:

 

PHOTOVOLTAIC (PV) CELLS – these collect solar energy & convert it to useable electricity.

  Wind turbines – these collect wind (kinetic) energy & convert it to useable electricity. The easiest way of understanding it, is by imagining a battery powered hand fan. Instead of the battery powering a motor that spins the blades to move the air, these wind turbines blades are turned by the wind & that energy is converted into electricity. It is the same principle of the hand fan, but bigger & working in reverse.

  Water turbines (aka water wheel) – these collect water (kinetic) energy & convert it to useable electricity. They work in exactly the same way as a wind turbine, but use moving water rather than moving wind. Water turbines are beyond the scope of this book as very few people have a suitable water source in their back gardens.

  Control elements:

 

CHARGE CONTROLLER – this acts as a buffer between the collection elements & the batteries. It is a clever piece of electronics that regulates the supply so that the batteries are protected from any electrical charge that could damage the batteries.

  Inverter – this inverts the batteries DC output into AC output.  Here in the UK & Europe, the nation’s supply is 230v AC; in the USA they have 110v DC. It is therefore important to know what form of electricity your household appliances need to run & also whether it is an AC or DC supply that they require.

  Store/Supply element:

 

THE BATTERIES – THESE store the electricity that has been harnessed by the system & stores it until the power is needed by the consumer. Here is a simplistic view of how these components all fit together:

 

  FIGURE 1 SIMPLISTIC view of the components (P Xavier © 2017)

  Can this Power the world?

  THE SIMPLE ANSWER IS yes. Professor Mehran Moalem of Berkley University in the US has calculated that the total world energy usage in 2015 was 17.3 Terawatts of continuous power (this total was derived from the world totals for coal, oil, hydroelectric, nuclear & renewables, all converted into electrical watts).

  This 17.3 Terawatts could theoretically be harvested using just 335km x 335km of solar panels. This would equate to an area of To put this in perspective, in Africa, the Sahara Desert covers 3.6 million Therefore, by placing solar panels over just 1.2% of the Sahara Desert, the world’s energy needs could clearly be Obviously, as people’s power needs increase, so too will the amount of solar panels needed to meet the demand.

  It is therefore feasible to harvest the sun’s free energy to provide useable power to the world. As a result, it would be expedient to closely examine the components that you can utilise to provide electrical power to your own little part of the world.

  But first, it will be a good idea to briefly explore & therefore understand electricity before looking at the photovoltaic panels in greater detail.

Chapter 3 - Some notes on electricity

    BEFORE WE START INVESTIGATING the various components that are needed in any given system, it is worth quickly refreshing something that you no doubt studied in school. So this is a quick refresher.

  Voltage is the measure of electrical potential. It is measured in volts (V). This can be thought of as pressure. If you think of water travelling through a pipe, the greater the pressure pushing the water through that pipe, the greater the volume of water will travel through that pipe every minute. If you now envisage a solar panel being connected to a battery, then the electricity will ‘flow’ to the battery. The greater the voltage being produced by the panel, the more electricity will flow into the battery. If there is no voltage, then there is no current. There is no ‘flow’. Nothing is moving. Power is only present when voltage & current are present.

  Current (or amperage) is the measure of the flow of electricity. This is expressed as amperes or amps (A). This can be thought of as how fast something is moving; imagine a car travelling at 60mph on a motorway, then the electricity is travelling from the solar panel to the battery at 60 amps. The speed at which electricity travels is actually very fast, much quicker than a car can travel. One amp is the equivalent to 6 billion, billion (6.2415 x electrons per second. Therefore 60 amps is extremely fast.

 

Electrical Resistance is the value given for how much a conductor opposes the flow. It is expressed in Ohms (Ω). It is the relationship of voltage & current, therefore if low resistance is desired then you need a high voltage, not high current. Which is basically opting for a much bigger pipe to allow a larger flow of water, not pushing water very fast through a small straw. The small straw would offer resistance & therefore seem to fight back.

  So that’s what the basic terms mean, now for some school boy maths & it should be noted that you do not need to commit this fully to memory or even understand it. It is here so that you can refer to it at any point if you need to use it. After all, it may prove to be useful.

  Ohm’s law

  OHM’S LAW STATES THAT at a constant temperature, the electrical current that flows through a fixed linear resistance is directly proportional to the voltage applied across it & it is inversely proportional to the resistance. Therefore the relationship between the voltage, current & resistance is what Ohm’s Law is based upon & it is always expressed in amps. Ohm’s Law is expressed mathematically in the following formula:

    THE VALUES ARE AS

   

THE TRIANGLE BELOW will help aid the understanding of Ohm’s law.

 

  FIGURE 2 OHM'S LAW triangle (P Xavier © 2017)

  Using the letters from this simple triangle will give each of the following formulae because the position of the individual letters relate to their position within Ohm’s law triangle:

        SO, BY KNOWING ANY two of the values (current, voltage & resistance), the third can be calculated.

  To find the voltage (V):

   

WHICH IS:

    TO FIND THE CURRENT (I):

    WHICH IS:

 

  TO FIND THE RESISTANCE (R):

    WHICH IS:

    NOW, TO CONSIDER POWER (P). This is simply the rate at which energy is absorbed or produced within a circuit. Therefore a power source will deliver or produce whilst the connected load will absorb it. Consider a light bulb. This receives electrical power & converts it into light & heat energy. The higher the bulbs wattage, the more power it will receive & use.

  By simply following the same principles observed in Ohm’s Law & substituting the values for electrical power, the following can also be calculated.

    THE VALUES ARE AS

    AS SEEN by knowing any two values it will be possible to calculate the power & the power triangle will help when remembering power calculations.

 

  FIGURE 3 OHM'S LAW 2nd triangle (P Xavier © 2017)

  As previously, using the letters in their position in the triangle will give the formula:

  To find the power (P):

    WHICH IS:

    ALSO,

    WHICH IS:

    ALSO,

    WHICH IS:

    THEREFORE IT CAN BE seen that a whole host of useful values can now be derived by just knowing two values.

 

Here is a useful list of formulae which could prove to be useful when wishing to derive further electrical information:

  To find the voltage from current & resistance:

    TO FIND THE POWER FROM current & resistance:

    TO FIND THE RESISTANCE from voltage & current:

    TO FIND THE POWER FROM voltage & current:

    TO FIND THE RESISTANCE from power & current:

    TO FIND THE VOLTAGE from power & current:

 

  TO FIND THE CURRENT from voltage & resistance:

    TO FIND THE POWER FROM voltage & resistance:

    TO FIND THE CURRENT from power & resistance:

    TO FIND THE VOLTAGE from power & resistance:

    TO FIND THE RESISTANCE from voltage & power:

    TO FIND THE CURRENT from voltage & power:

 

  THESE TWELVE FORMULAE should therefore be referenced if any of the values need to be calculated. Now it’s time to examine the photovoltaic system components in detail.

Chapter 4 - Photovoltaic cells

    PHOTOVOLTAIC CELLS (aka solar panels) come in many shapes & sizes, but all convert light energy directly into electrical energy by a process called the ‘photovoltaic effect’ effect’. This ‘photovoltaic effect’’ is best described as the creation of an electric current in a material directly from exposure to light. The ‘photovoltaic effect’ was first observed by the notable French Physicist A.E. way back in 1839. The entire process is notable in that the process generates no pollution & once installed it produces no greenhouse gasses. It does have its drawbacks though. The cells need to be at a right angle to the sun or there is a substantial loss of power. Therefore if a tracking system is not used, between 10 – 25% of available power is lost. Also, any dust on the cells or clouds obscuring the sunlight will also have a negative effect on the potential output. The geographical location of the cell is therefore a consideration as not all parts of the world receive the same amount of sunlight during the year. In the extreme North & South they may get many hours of sunlight in the summer, but their summers are very short in duration & their winters are very long & dark. The equator is therefore the best location for housing photovoltaic cells as the length of days are more equal throughout the year & have more sunlit hours. The rule of thumb is the nearer an installation is to the equator, the greater the potential output would be. Figure 4 is shaded to show this principle, where the areas with higher annual sun are shaded in red.

 

  FIGURE 4 GLOBAL ANNUAL sun (SolarGIS © 2013 GeoModel Solar)

  Chances are that you do not live at the equator, but that does not mean you will not be able to harness a useable amount of electrical energy. However, it should be remembered that you will achieve a lower output compared to an identical system nearer to the equator.

  Photovoltaic terminology

  EACH PHOTOVOLTAIC CELL looks like a blue/black silicone wafer square (it looks like glass) that has the corners cut off. They typically measure between 125 – 150mm.

 

  FIGURE 5 PHOTOVOLTAIC cell (Public Domain Image © 2005)

 

These photovoltaic cells are linked together & enclosed within a lightweight plastic or aluminium frame, set behind glass to keep them clean & exclude moisture & dirt. This ‘unit’ is known as a PV

 

  FIGURE 6 CUTAWAY OF a typical PV module (P Xavier © 2017)

  A PV panel is two or more PV modules that are joined together to form one larger panel to make installation easier. Two or more PV panels are known as a PV

 

  FIGURE 7 PV CELL, PV module, PV array (P Xavier © 2017)

 

There are numerous materials that are used to make the PV cells, they all operate in the same manner, but some are more efficient than others. The different materials are split into four main types:

  1. Monocrystalline silicon

  Monocrystalline silicon (Mono-Si) is ‘grown’ from molten silicon into a large ingot which forms one large silicon crystal. The ingots are then sliced into thin hexagonal slices (wafers). They are currently one of the most expensive as they are the most efficient. They can achieve an efficiency of 15%.

  They perform well in low light conditions, but are not so good in cold conditions; therefore winter conditions in the UK will affect their efficiency.

  2. Polycrystalline silicon

  These are sometimes known as multicrystalline & are made by casting silicon into a cast which is then cooled. It is then sliced into thin slices as is the Mono-Si. These wafers are given an anti reflective coating that gives it a blue hue that ensures maximum absorption of light. They can be differentiated from Mono-Si as they contain individual crystals which are clearly visible.

  In figure 8, Polycrystalline (Left) can be compared to monocrystalline (right).

 

  FIGURE 8 POLYCRYSTALLINE & monocrystalline (Public Domain Image © 2014)

  Polycrystalline cells can achieve efficiencies of approximately 12% & are therefore less expensive than Mono-Si cells. Together, Monocrystalline & Polycrystalline account for 93% of the worlds solar

  3. Amorphous silicon

  Amorphous silicon is made from non-crystalline silicon gas that is sprayed onto a substrate such as glass, plastic sheeting or even plastic film. A conducting grid is then attached. These only achieve between 6 – 8% efficiency so are considered inefficient. A large area is needed to produce a reasonable amount of electricity, so these are not usually suitable for domestic installations. Due to the relatively low cost of manufacturing, these do find their way into small cheap electronics such as pocket calculators. This type of cell accounts for 4.2% of global solar panel sales.

  4. Hybrid

 

These are just those that use two different types of PV technology. For instance, a Monocrystalline silicon cell could be covered in a top layer of Amorphous silicon, which would then be classed as a hybrid.  Hybrid cells have the general operating characteristics of being good in higher temperatures & have a high efficiency. Some up to 18%. They do however tend to be expensive. These were the four main types currently on the market in the UK & EEC, but there are many others available. There are many other kinds of thin film cells that are built using some material other than silicon. These cells include cadmium telluride (CdTe (8 - 9% efficiency)), copper indium gallium selenide (sometimes known as CIGS, which is 10 - 12% efficient), copper indium diselenide (CIS 10 - 13% efficient), & also organic photovoltaic cells. The only cell that is currently as cost-efficient as silicon panels is the cadmium telluride cell. CIGS cells show the most promise in terms of efficiency in the future but contain smaller amounts of toxic cadmium than other alternatives. Organic photovoltaics are photovoltaic cells that utilise cheaper plastics & electronics that are made of conductive organic molecules. These are not widely used. Concentrating photovoltaic’s are also available, but are not widely used. These photovoltaic cells simply use some sort of solar collector which is generally composed of lenses &/or mirrors which are used to concentrate the sunlight on to a smaller number of photovoltaic cells. This decreases the number of overall cells needed & therefore decreases the overall cost, whilst still maintaining a significant energy output from the panel. This type of cell setup could be more efficient, but new methods need to be fully developed to allow the cells to deal with the resultant increase in

  Power

  THE POWER OUTPUT OF a solar panel can be seen in a performance graph. This type of graph is known as an I-V curve graph (I=current –

V=voltage). The current is on the vertical axis & the voltage on the horizontal.

 

  FIGURE 9 PV I-V CURVE graph (P Xavier © 2017)

  When a solar panel is exposed to sunlight, it is functioning. Therefore the performance will be at some point on the graph. Its point will be dependant on a number of factors such as the temperature & the solar irradiance (the amount of energy reaching the PV from the sun). Figure 10 shows the annual average of solar irradiance in Europe.

 

  FIGURE 10 AVERAGE EUROPEAN solar irradiance (European Union Joint Research Centre © 2011)

  It should be clear from figure 10 that the South of the UK is much better for PV installations than the North of Scotland, but both locations are very poor when compared to Southern Europe.

  The maximum power can be calculated as follows:

  Pmax = x

  If you opt to install a Maximum Power Point Tracking (MPPT) Charge Controller, then this can alter the input voltage of a module to ensure that the most power is received from the module.

  The Maximum Power Voltage of the solar panel is typically 70 – 80% of the maximum voltage The Maximum Power Current of the solar panel is approximately 90% of the short circuit current The Short Circuit Current is the maximum achievable current if there is no resistance. Or, to put it another way, the electricity is using another (shorter) path & not travelling on the route that was intended. There is therefore a lower resistance & a significant flow of electricity.

  The Open Circuit Voltage is the maximum potential voltage that is achievable, but at there is no power & no current as it is an ‘open circuit’. Figure 11 shows the variability of output given differing lighting conditions due to the effect of clouds upon the PV array, represented as an I-V curve.

 

  FIGURE 11 WEATHER EFFECTED I-V curve (P Xavier © 2017)

  For any given set of operational conditions, cells have a single operating point where the values of the current (I) & Voltage (V) of the cell result in a maximum power output. These values correspond to a particular load resistance, which is equal to:

    JUST AS SPECIFIED BY Ohm's Law.

  The power (P) is given by:

   

A PHOTOVOLTAIC CELL for the majority of its useful curve acts as a constant current source. However, at a photovoltaic cell's Maximum Power Point (MPP) region, its curve has an approximately inverse exponential relationship between current & voltage. At a photovoltaic cell's MPP region, its curve has an approximately inverse exponential relationship between current & Typically, when researching which PV modules you will incorporate into your installation, the values will be based on standard test conditions. These should be thought of as best case scenarios which will not be achieved, but will give a good value when comparing different manufacturer’s data.

  The sun – a moving target

  BEFORE CALCULATING the correct angle at which to set your array, it must be realised that the angle of the sun above the horizon moves throughout the year due to the tilt of the earth. It is at its highest arc across the sky during the summer solstice which is June 21st. It is at its lowest arc across the sky during the winter solstice which is December 21st. It is also exactly half way between these two points twice a year. That is during the vernal equinox which is March 21st & again on the autumnal equinox which is September 21st. It is therefore important to take these positions into account when calculating the optimal angle to set your array.

 

  FIGURE 12 PATH OF SUN throughout the year (P Xavier © 2017)

  Figure 12 shows the path the sun takes through the sky during both the summer & winter solstices. The hatched lines being the maximum & minimum angle above the horizon during both solstices. Therefore the optimal tilt in the winter would be more vertical in the winter than summer to maximise the output from any solar array.

  True North

 

IT IS ALSO IMPORTANT to know that your array should face directly South. If you use a compass to find North, it will point towards magnetic North, not ‘true North’. Also, magnetic North is not a fixed point, it is constantly on the move. It has been situated in Northern Canada for many years, but is now assumed to be heading towards Northern Russia. Therefore it is imperative that you find true North, or your array will not be in an optimal set up. Figure 13 shows the position of the ‘magnetic poles’ in 2005 & it should be clear that they are (most likely) vastly different to the North & South poles that you probably imagine (those imaginary points at the centre of the Arctic & Antarctic). These points in

the Arctic & Antarctic only exist on maps & in adventure stories. They do not feature in the real world.

 

  Figure 13 Magnetic poles in 2005 (Public Domain Image © 2015)

  The difference between true North & magnetic North is called the Magnetic which is basically the difference between the two. A GPS or a phone with GPS will point to true North; therefore you do not need to allow for any adjustments.

  There are therefore a lot of sources on the internet that will report the current magnetic declination for your location. All you have to do is make a quick internet search. If you have an adjustable compass, like the one in figure 14, you can adjust it manually if you have found the magnetic declination.

 

  FIGURE 14 ADJUSTABLE compass (Public Domain Image © 2005)

  The number given will be either positive or negative & this will be because of your position either East or West of the agonic This magnetic variation (the difference between magnetic North & true North) is caused by the North & South Poles not being directly 'opposite' one another. The lines of the earth's magnetic field do not run in a regular pattern either as they are affected by other local magnetic forces & also the magnetic pole is always on the move. Some of these lines of magnetic variation are east of true North & others west of true North. Between the East & West lines there is a line of zero magnetic variation where the compass does actually point to true North - this line is known as the agonic line.

  If you look at an OS map of the UK, it can be a little confusing as there are 3 North’s. There is ‘true North’, which is the line between the theoretical North & South Pole’s. The second is ‘grid North’, which is the alignment of the map (because the map is a 2D representation of a 3D world) & there is ‘magnetic North’. The value for magnetic North will be set when the map was printed, but will have changed a little since printing.

Using the ‘magnetic North’ value on the map, adjust your compass for magnetic North. If the value on the map is positive (to the right of North) you will need to turn the ring on the compass to compensate. If the value on the map is negative (to the left of North) you will need to turn the ring the other way to compensate.

  The UK is very near to an agonic line. It runs through France & goes Northwards through the North Sea. As an example (because it is fairly central in the UK), Colmore Row in Birmingham, UK (52º 28’ 52.4” N, 1º 53’ 54.7” W) has a magnetic declaration of -1º 14’ (so that the difference between true North & magnetic North is -1º 14’). Therefore the compass ring will need to be turned 1º to compensate for this magnetic declination. South, which is what you are actually interested in finding, is obviously 180º from North, therefore it will be directly behind you. A more detailed description of this process can be found by simply undertaking an internet search.

  A less precise method to find true North simply involves an analogue watch. First check that the watch is showing the correct time. Point the hour hand at the sun. The angle exactly half way between the hour hand & 12 o’clock position will be the direction for South. In the UK, BST is adopted & therefore the clocks have gone forward an hour (between spring & autumn), therefore during BST use the one o’clock position instead of the 12 o’clock position.

  Alternatively, at night time (in the Northern hemisphere), look at the stars searching for the star Polaris (The North Star). If you face this star, you will be facing North. There are many other less precise methods to find North/South, but these are far too inaccurate to be considered. The most accurate will be the magnetic declination method.

  Calculating the optimal angle

 

THERE ARE TWO METHODS to calculate the tilt angle, both of which are very simple. However you will need to know the latitude for your location.

  The simplest way to do this is to find your location on Google maps. Zoom in to your location & right click on the point you require. From the drop down menu that appears select ‘what’s here?’ & the co-ordinates will appear.  As before, Colmore Row in Birmingham, UK (52º 28’ 52.4” N, 1º 53’ 54.7” W) will be used in this example.

  Colmore Row has a latitude of 52º. In the winter simply add 15º. In the summer, simply subtract 15º. Therefore the calculation for the winter is as follows:

    FOR THE SUMMER:

    THEREFORE IT CAN BE seen that to get the optimal energy output for a typical solar panel array, it would need to be set at an angle of 37º (from vertical) at the summer solstice & 67º (from vertical) at the winter solstice. For a slightly more accurate method of calculating the tilt, use the following method.

  Winter solstice

  Take your latitude & multiply it by 0.9, then add 29º & subtract it from the vertical. Therefore again using Birmingham as the example:

 

  THEREFORE USING THIS accurate method to calculate the optimal winter angle, the panel should ideally have a tilt angle of 14.2º from vertical.

  Summer solstice

  Using your latitude, multiply it by 0.9, then subtract 23.5º, then subtract from vertical.

 

  THEREFORE USING THE accurate method to calculate the optimal summer angle, the panel should ideally have a tilt angle of 66.7º from vertical.

  Vernal & autumn equinox

  Again, using your latitude, subtract 2.5º then subtract it from vertical.

 

  THEREFORE FOR THE EQUIDISTANT points (vernal & autumn equinox’s) on the calendar between the summer & winter, the panel should have a tilt angle of 40.5º from vertical. All these three angles are shown in figure 15.

 

  FIGURE 15 ANNUAL PV angles (P Xavier © 2017)

  There are also many online calculators or free downloadable apps that will do these calculations for you if you wish to have a check on your calculations.

  Shading

  SHADING CAN HAVE AN adverse effect upon any solar panel. Often, even if a small proportion of the panel is shaded then it can have a huge affect on the output. As can be seen in figure 16, the electrical energy flows through each panel like water through a pipe & a shadow (even a partial shadow) on the panel will act as a blockage to the theoretical pipe, stopping the electrical energy from flowing through it.

 

The panel on the top left (in unobstructed sunlight) is producing 100% of its possible energy output, whilst the panel on the top centre is under partial shadow which has the effect of blocking the flow of electricity through that panel. That panel is therefore now producing 0% of its potential, as is the panel on the top right, that too is producing 0%. This problem can be alleviated by obtaining panels that are fitted with bypass diodes.

 

  FIGURE 16 EFFECTS OF panel shading (P Xavier © 2017)

  Bypass diodes

 

THESE ARE BASICALLY gates that allow the flow of electricity to take an alternative route if partial shading occurs. They redirect the electricity to allow smaller sections of the panel to operate independently, rather than as a whole unit.

  As can also be seen in figure 16, where the panel on the bottom left is operating at 100% of its possible energy output, whilst the panel on the

bottom middle is under partial shadow which has the effect of blocking the flow of electricity through the panel. However, this panel has bypass diodes fitted & therefore still allows the panel to function; in this instance at 66% of its possible energy output. The panel on the bottom right has even more shadow on it, yet it is still producing 33% of its possible output. It is therefore far better to obtain panels with bypass diodes fitted.

  Most large solar modules have bypass diodes fitted as standard, but it is worth checking with the manufacturer first before making any purchases. Some have more bypass diodes than others. Obviously, to maximise the output potential, the greater the number of bypass diodes will be needed.

  Inter row spacing

 

ALSO, WHEN DESIGNING the spacing of the panels, it is important to realise that if the panels are too near to one another, this can cause shadows to fall upon the neighbouring panels.

  This may not be a concern in summer months, but during winter months, when the sun is lower in the sky, it casts long shadows. The shadows on the winter solstice (December 21st) are longer than at any other time of year. Therefore as a rule of thumb, spacing should be 3 & a half times the height of the array.

 

  FIGURE 17 INTER ROW spacing (P Xavier © 2017)

  However, if you wish to calculate the exact spacing required, you will need the following simple formula which assumes that the panels are South facing:

    THE VALUES ARE, H BEING the height of the top edge of the solar panel from the floor or ground, y being the sun’s altitude & azimuth being z, then the distance d is easily If however you find mathematics a little daunting, there are numerous free online calculators & downloadable apps that will make the calculations somewhat easier. Alternatively, you could just create a scaled model & measure the shadow throughout the day between 9am & 3:30pm on 21st December.

  Temperature

  ALL SOLAR PANELS ARE affected by the ambient temperature. When they reach 25ºC their performance level drops. They will then drop by

approximately half a ºC for every degree above 25ºC. Also when the panels are very cold, the opposite happens. Their performance increases. Therefore on those crisp clear winter days the output from each panel is increased.

  Figure 18 will give you some idea on the temperature voltage ratio. This is all due to the internal resistance of the components. This may sound like a positive effect, but it can actually have its drawbacks.

 

  FIGURE 18 TEMPERATURE voltage ratio (P Xavier © 2017)

  As the voltage increases in winter, you must ensure that the remainder of your system has been overdesigned to cope with this increased voltage. If you do not, you can run the risk of frying the electronics, blowing fuses or tripping the circuit breakers.

  Most manufacturers will therefore list a temperature coefficient for the open circuit voltage & the short circuit current This can be listed as volts per ºC below 25ºC, or even sometimes expressed as a % per ºC below 25ºC. For example:

  -0.35%/ºC

  Therefore for every degree change downwards, the voltage will increase by the stated amount. In this case 0.35%, so if the PV module’s temperature reduced by 1ºC, then the voltage would increase by 0.35%.

  It is therefore important to know the exact lowest temperature recorded at your location. The average lowest is just not good enough, it has to be exact. The lowest recorded temperature in Scotland was -27.2ºC in Braemar, Aberdeenshire on 10th January 1982. In England it was -26.1ºC in Newport, Shropshire on 10th January 1982. In Wales it was -23.3ºC in Rhayader, Powys on 21st January 1940 & in Northern Ireland it was -18.7ºC in Castlederg, County

  However, all solar panels are rated by their manufacturers who assume that their modules are operating at 25ºC. They call this the Standard Test Condition (STC), but it should be clear therefore that in certain weather conditions it will be possible to outperform the STC.

  Also, once installed, each panel will awake every morning without being in direct sunlight. As such they will be at the temperature they were during the previous night & will not be producing any current but will be in ‘open circuit voltage’. At this point if the temperature is below 25ºC, then the will be greater than the panel’s STC rating. When sunlight reaches the panel/s, the electrical energy will begin to flow & voltage will drop from & move towards the point.

 

As the day progresses, the temperature of the panel will increase & how much it will increase will depend on the location factors. If it is sited on a roof with less than 150mm air gap between the panel & roof, then you can expect a temperature rise of +35ºC above ambient for the panel. If the air gap is more than 150mm, then +30ºC above ambient can be expected. If the panel is pole mounted or elevated above the ground then +25ºC above ambient should be anticipated. Therefore on a hot summer day reaching 35ºC, any rooftop panels that were installed with a small air gap could potentially reach a temperature of 70ºC.

  It should be evident that there should be an operating window rather than just one STC value of 25ºC.

  It would therefore be best to design your system to cope at both ends of the temperature spectrum. This can be done using this simple formulae:

  Temperature difference x at STD

  Low temperature calculation

 

THEREFORE IF IT IS assumed that a typical solar panel has a rating of -0.33%/ºC & we take the lowest recorded English temperature (which was Shropshire -26.1ºC), the formula would be as follows:

  Lowest temperature = -26.1ºC & STC (25ºC), therefore the difference is 51.1ºC

  51.1ºC x -0.33%/ºC = 16.86%

 

Therefore, the solar panel in this example will gain 16.86% at -26.1ºC.

  If the solar panel was rated at 260w, then the output at the lowest UK temperature would be:

    2.6 x 16.86% =43.836

  Rounded up to 43.8

  Therefore 260w + 43.8 = 303.8w at -26.1ºC

  THE MAXIMUM WATTAGE that the system will have to cope with at low temperatures should be 304w.

  High temperature calculation

 

IF IT IS ASSUMED THAT a typical solar panel has a rating of -0.33%/ºC & we take the highest recorded English temperature (which was in Faversham, Kent 35.8ºC on 10th August 2003), the calculation would be as follows:

  Highest temperature = 35.8ºC & STC (25ºC), therefore the difference is 10.8ºC

  10.8ºC x -0.33%/ºC = 3.564%

  Therefore, the solar panel in this example will lose 3.564% at 35.8ºC. If the solar panel was rated at 260w, then the output at the highest UK temperature would be as follows:

    2.6 x 16.86% = 3.564

  Rounded up to 3.6

  Therefore 260w - 3.6 = 256.4w at 35.8ºC

  SO IT CAN BE SEEN THAT the operating window for this theoretical solar panel would be in the range of 256.4w – 304w, despite being rated at 260w.

  Serial, parallel or combined

  AS YOU WILL MOST DEFINITELY calculate that you will require more than one module, you will need to look at stringing each of them together. You will therefore have one of three choices. Either to construct them in a series, in parallel, or a combination of part series, part parallel.

  Before you can decide, you need to know a few things about the options. As you have seen, the capacity of every solar panel is rated in watts. The wattage is calculated by multiplying the panel’s voltage by the amps of current it produces. Any installation will need to find the right balance between voltage & amps to achieve the desired results.

  The size of the required installation along with the individual components used should be the major factor when deciding which option to choose.

  First consider series connections.

  Series connection

 

A SERIES CONNECTION is when each of the solar panels are connected to the next in a The total voltage of the panels are summed together, but the amperage remains as a constant. When wiring the panels in a series, there is one cable used & the panels form a chain.

  Figure 19 demonstrates this principle where the panels are strung together in a series with the electrical energy flowing from the panel through the negative terminal, just like a battery.

  Figure 19 shows 4 solar panels, each rated at 12 volts & 5 amps. This results in a cumulative output of 48 volts & 5 amps. It is constructed by connecting the positive (+) terminal on the first panel to the negative (-) terminal on the next panel.

 

  FIGURE 19 SERIES CONNECTION (P Xavier © 2017)

  The downside of this system is shading on the panels. If a partial shadow is blocking the throughput of the electrical energy, then the entire system can be cut off (blocked) or at best greatly diminished, as demonstrated previously (see section on shading). If you consider old Christmas tree lights, if one bulb is broken, then none of the lights will work. As there is one circuit, any problems will affect the whole as it operates as one circuit.

  Parallel connection

 

TO ACHIEVE A PARALLEL connection, connect each of the positive (+) terminals together & connect all the negative (-) terminals together on each of the solar panels. Typically, each of the positive terminals are connected to one centralised positive wire to make life simple. All the negative terminals are similarly wired up to a central negative wire. They are then said to be connected in parallel.

 

  FIGURE 20 PARALLEL connection (P Xavier © 2017)

  If the same panels that were used as the example in figure 19, but were instead connected in parallel (figure 20 (four solar panels, each rated at 12

volts & 5 amps)), then the total amperage of the panels are summed together, but the voltage remains as a constant.

  Therefore, the resultant output would be 12 volts & 20 amps. If there were a shadow across one of these panels, or if a panel was not functioning, then it would not affect the remaining panels, so removing one panel would result in an output of 12 volts & 15 amps.

  Combined system

 

THE CHOSEN ROUTE THAT you would adopt would be dependant on your desired output. If you needed more amperage you will need to increase the panels in parallel. If you require greater voltage, then you need to increase the panels in the series. If you wish to have a higher voltage & higher amperage, then you will need a combination of both systems to achieve the desired level of output.

  Mixing & matching

 

MIXING & MATCHING SOLAR panels is not generally recommended. The problem does not lay with different manufactures of solar panels being incompatible with another’s, but with the fact that they can have different parameters (voltage, wattage & amperage) & also a different performance degradation. As was noted previously, solar panels can be connected in a series to obtain a higher voltage. However, great care must be taken to ensure that the maximum system value is not exceeded.

  As in the parallel connection example seen previously, with 4 solar panels, each rated at 12 volts & 5 amps, which had a cumulative output of 12 volts & 20 amps. If the same set up is used, but now focus on the wattage.

If each panel is rated at 120 watts, then the total wattage for the array would be 480 watts (120 watts x 4).

  If a panel in the array has a lower wattage than the others, then this may not pose too much of a problem provided that the panel with the lower wattage has the same voltage as the others.

  Looking at the parallel setup once more, but this time assume that the panels are rated (from left to right) as 140w, 150w, 150w & 150w, the resultant output wattage would be 590 watts. But if a similar setup were to occur in a series connection, then the lower panel will act as a partial blockage as it will only allow its rated wattage to pass through & therefore a lower output will be the result.

  If the same panels were constructed as a series setup, the resultant wattage would be 560 watts. The panel with a lower rating is dragging the system down as the lower rated panel will only allow its rating to flow through the entire system.

  So it can be seen that it is possible to mix different modules in an array, but unless careful consideration is given at the design stage, the resultant output could be far lower than expected.

  When connecting different panels in an array, it is not the different wattage that causes concern, but the current in a series connection & voltage in a parallel connection. Both of which will reduce the design performance of the array.

 

Also, another design consideration is to ensure that the maximum output voltage from an array is lower than the maximum input DC voltage on the inverter.

  It is also important to use only solar panels with the same current rating if wiring them in a series or the performance will be reduced. If for example you wire a 3 amp panel with 3.5 amp panels, then the overall system amps will be dragged down to 3 amps.

  Similarly, only panels of an identical wattage should be wired in parallel or the same negative effect will result. If a 12v panel & a 24v panel were used, the array would only function at 12 volts.

  Compared to voltage & current, wattage is less of an issue. If panels of a different wattage were used together in a series, then the total of each will be the result (provided they both have the same current). A 100w panel & a 60w panel would give an output of 160 watts. It is however important to ensure that the output wattage is inside the design window for the inverter. If the mixed panels have different current ratings, then the wattage will be lower than expected (less than 160 watts).

  Also, if a 60w panel & a 100w panel are wired in parallel, the total power would be 160w, but only if both panels were of equal voltage. However, if their voltages differ, then the output will be lower than expected (less than 160 watts). It can therefore be seen that it is possible to mix & match, but it can cause problems if not carefully designed.

  Weather

 

THE WEATHER ALSO HAS an impact upon a solar array, but not as much as you’d probably imagine. PV panels work just the same in bad weather, just their output is diminished. Clouds do impact upon electricity output, so in the UK, any given array will never be able to compete with a comparable setup somewhere sunny, such as California. However it is possible to get a meaningful output all year round. Figure 21 shows how a good system should perform throughout a sunny day.

 

  FIGURE 21 PV PERFORMANCE on a sunny day (P Xavier © 2017)

  The output gradually increases throughout the day until noon, after which it slowly starts to diminish. Figure 22 shows how the performance can be diminished by certain weather conditions.

 

  FIGURE 22 PV PERFORMANCE over a cloudy morning (P Xavier © 2017)

  It should be evident that output has been reduced, but has not stopped entirely, which is good news for anyone in the UK who wishes to install solar panels. In fact, there are so many cloudy days in the UK, when illumination calculations are made for industrial & commercial buildings; engineers use an average value called ‘standard overcast sky’ for the background illumination. Luckily solar panels still work on cloudy days as they not only absorb direct light from the sun, but also diffused light which is light reflected off things such as buildings & even light diffused by & through the clouds themselves.

  Rain should be seen as a positive thing as it will clean the solar panels in the array. It is surprising just how much dirt, pollen, dust, leaves & guano can build up on the panels. The panels themselves are sealed units, so there is little chance of any water ingress.

  Temperature has already been dealt with earlier in the chapter, but not wind. A strong wind on the panels will have the result of dropping their temperature & for every degree change downwards, the voltage will increase, which again should be seen as a good thing.

  Snow too can be beneficial. Provided the panels themselves are not covered in snow, the output voltage should increase due to the lower air temperature & the increased amount of diffused light being reflected off the snow.

  Other points of note

 

EACH SOLAR PANEL NOT only has a power rating, but also a ‘power degrade percentage’. This means that panels from different manufacturers degrade at different rates over time. Also, the rate that they degrade does not always correspond with their stated value; therefore it is virtually impossible to match panels from different manufacturers.

  If the panels are connected in a parallel arrangement & one has a lower voltage than the others, then it will reduce the output as it will act as a bottleneck. All the remaining panels in the array will therefore be underperforming.

  Also, if the panels are connected in a series & one of the panels has a lower current than the others, then the total output will be lower as the lowest rated panel will drag down the others because it will act as a bottleneck. All the remaining panels in the array will therefore be underperforming. If you utilise a MPPT charge controller & mix solar panels which have different ratings, then the charge controller will not be able to function correctly. It simply would not be able to cope. It would find it impossible to attain the optimal current & operating voltage as this would be different for each type of panel that was being used.

  Rules of thumb

 

ONLY CONNECT PANELS in a series connection that have the same manufacturer & have the same current. In a series connection, if you have no option but to use panels from different manufacturers, then you must ensure that they have the same current rating. Only connect panels in a parallel connection which have the same manufacturer & the same voltage. In a parallel connection, if you have no option but to use panels

from different manufacturers, then you must ensure that they have the same voltage rating.

  The main rule of thumb is to remember that you should (wherever possible) avoid connecting different solar panels in the same array as either the current or voltage will be mismatched. Therefore the best case scenario would be a reduction in either the current or the voltage. In a worst case scenario, the mismatch will damage other components in the overall energy system.

  Module data

  EACH MODULE WILL HAVE the electrical ratings on the rear of the unit. This data will be invaluable when making calculations for that particular module.

 

  FIGURE 23 PV MODULE rating sticker (Public Domain Image © 2015)

Chapter 5 - System enhancements

    IT IS POSSIBLE TO INSTALL a basic PV system without any enhancements, but it is likely that you may wish to include into the system some enhancements. Some could be purely cosmetic & some can increase your energy harvest. You could design your own enhancements or purchase purpose built items. Whatever the case, it is worth spending a little time examining the available options.

  Racking for the PV array

  ALL PV PANELS WILL need to be mounted on something. Whether it is a simple rail system, or a fully adjustable system, the complexity of the system is your choice but the more complex it is, the more expensive it will be. It can account for approximately 25% of the PV installation costs, therefore it would be prudent to consider minimising costs, but not quality. The racking will after all act as the foundation for your PV’s.

  Whatever system you design or buy, it must be capable of withstanding the rigors of the weather. There will be wind loading to consider, snow loading. Corrosion if your site is near the coast or heavy industry. Also you must allow for thermal expansion as your PV array will expand in the sun & contract every night. It is therefore important to utilise sturdy materials with appropriate fixings.

 

If you decide you can use a suitable roof slope that benefits from direct sunlight, then you should minimise the effect of shading on your PV panels. It is also advisable to minimise the length of the cable run to the batteries, thereby saving money & also commercially bought roof mounted PV racking is amongst the cheapest, so that is a double saving.

  However, if you follow the slope of the roof, then the system will not be adjustable & therefore in all probability, the array will never be at an optimal angle to harness the sun’s energy, you will have a trade-off. The fact that you are utilising the existing slope will save you on the installation cost, but it will never maximise your output.

  Roof mounted racking – on-roof & in-roof

 

ALL ON-ROOF MOUNTING systems designed for pitched (not flat) roofs follow similar methodology. They all in some shape or form are fixed to the rafters. In the following example, the fixing bracket is fixed directly to the rafter, by screwing through the felt & the bracket typically can be either U or L shaped.

 

  FIGURE 24 U BRACKET (Public Domain Image © 2017)

 

The bracket is securely fixed at one end to the rafter.

 

  FIGURE 25 U BRACKET fixed in place (Public Domain Image © 2017)

  The roof tile is replaced on top of it & the other end of the U shaped bracket is left exposed on top of the tile ready to accept the rails that will support the PV panels.

 

 

FIGURE 26 TILED OVER bracket with rails fitted (Public Domain Image © 2017)

  This type of system should be thought of as a ‘roof hook’ system as the U (or L) brackets, hook around the tile & then everything else bolts onto it.

  As stated earlier, this system, once fitted is static & therefore can only be set to the angle of the roof slope & not to an optimal angle. This system & other systems that use a raised rail above the roof slope incorporate a ventilation space under the panels & the entire panel system must not extend more than 200mm above the existing roof slope to ensure it complies with the UK’s Permitted Development legislation. Also, this system has some noticeable drawbacks.

  Firstly, a significant amount of the roof tiles will need to be removed & then replaced once the brackets have been secured. The brackets themselves also stop the upper tile making contact with those below, therefore there will be a gap between the tiles which could form a conduit for the ingress of water & may also work the tile loose or spall the tile if that water repeatedly freezes & expands. Also, there has been no allowance designed into this system to route the cabling into the roof space, therefore a flashing detail will have to be made or purchased that matches whatever tile or slate pattern is present on the roof.

  If you decide to purchase a flashing detail to route the cabling into the roof void, there are many products on the market to choose from, but which ever product you opt for it is important that it matches &/or is compatible with your roof tiles & whatever size cabling you wish to route. As an example, here is one such flashing system available to purchase (called Dektite) in the UK & EEC.

  Figure 27 demonstrates how this flashing system is used. It should be clear that the cabling threads through the flashing into the roof void below whilst maintaining a watertight seal. If the colour of the flashing is an important consideration & matching the colour proves to be a problem, it is possible to position the flashing so that it is obscured from view under the panel, or under the rail.

  FIGURE 27 DEKTITE FLASHING (DEKS Industries © 2017)

  Other systems are available including different sizes, colours & also flashings suitable for pipework from solar hot water systems.

  Other roof on-roof mounted PV systems are just a variation on a theme. They all need to be secured to the rafters & a fixing (of some sort) projects above the tiles, to which the PV mounting rails are attached. Some systems employ bolts, some employ brackets. All these are available online for any potential DIY’er.

  Figure 28 shows an alternative fixing system that utilises projecting bolts that have integral metal flashings.

 

 

Figure 28 Fixings with integrated flashings (Ibacos © 2017)

  There is also the in-roof system to consider, which also utilises the roof slope. This system is aesthetically more appealing as it is constructed to finish flush with the roof slope, rather than being fixed above it. Generally they are fixed without any rails. The number of fixing components are therefore reduced & as a consequence the installation time is also reduced. The entire system is held in place by HDPE panels which are attached to the rafters. The PV panels are then attached to the HDPE panels & the surrounding tiling is constructed flush to the PV panels. The PV panels undertake the same function as the tiles, therefore there is only a single skin of materials & therefore there is a cost saving on the roofing materials. This system is better suited to new build rather than being retro fitted, but they can be retro fitted, but the existing roof tiles will need to be removed to allow the installation to commence. If these panels are retro fitted, a large section of the roof surface will be clad in PV panels, not tiling, therefore there will be a certain percentage of tiles removed from the roof. This has a positive effect as it will reduce the loading on the roof.

  Figures 29 & 30 show the HDPE panels fixed in position, ready to accept the PV panels. Note that the roofing felt is visible in the centre of the

panel along with the tiling battens. The surrounding area has also been tiled flush to the HDPE panels.

 

  FIGURE 29 HDPE PANELS ready to accept PV panels (Severn Valley Renewables © 2017)

 

  FIGURE 30 HDPE PANELS ready to accept PV panels (Severn Valley Renewables © 2017)

 

  FIGURE 31 THE FINISHED in-roof system (Severn Valley Renewables © 2017)

  It should be clear that when compared to any on-roof system, this in-roof system is more visually appealing. The entire system is integrated into the roof structure therefore there is no need for separate openings for the electrical cabling. The HDPE panels are strong, stable, inexpensive, watertight & far lighter than any roof tiles.

  Again, there are many different products on the market. Any selection should be decided by the unique conditions at your site & property. These systems are compatible with all types of roof tiles (roman, interlocking, flat, slate & even steel trough) as the tiles are cut to fit around the panels. These panels can also be fitted as either landscape or portrait layouts.

  These in-roof systems can typically be installed on roofs with a slope between 15 - 50º & can be obtained in various sizes making them able to fit almost any PV panel. They are also highly resistant to wind lift as there are no open channels or open cavities on the underside for the wind to get

under. HDPE is also resistant to chemical attack & therefore these are better suited to costal areas & areas subject to industrial pollution.

  Figure 32 shows a close up view of the trim around the PV panel & it should be noted that the slate roof tiles have been cut to fit around the installation.

 

  FIGURE 32 CLOSE UP of the edge detail for the in-roof system (Severn Valley Renewables © 2017)

  This type of system blurs the line between building integrated photovoltaics & building applied photovoltaics.

 

Flat Roof mounted racking

 

A FLAT ROOF IS DEFINED as a roof slope that is less than 10º from horizontal, therefore any roof with a minimal pitch is categorised as a flat roof, whether it is flat or not. The racking systems used on domestic flat roofs are the same type that are typically used on commercial & industrial rooftop installations, therefore there is no difference to the types or materials, only the quantity as domestic installations are utilise much smaller installations.

  The cheapest type available on the market is similar to a plastic tub, as can be seen in figure 33.

 

  FIGURE 33 PLASTIC TUB (Public Domain Image © 2017)

  These tubs are designed to sit flat on the roof & are designed to be set at a static angle. These are designed to be filled with ballast or concrete & therefore have minimal fixings to the roof structure. Due to their extreme weight, they are more suitable for high strength roofs & therefore are highly unlikely to be suitable for domestic flat roof applications. Figure 34 shows these tubs set on the roof of a commercial property. PV panels are attached to the tubs with either clamps or clips.

 

  FIGURE 34 PLASTIC TUBS on a commercial property (Public Domain Image © 2017)

  Another similar system that can be weighted down with concrete blocks, or bolted down involves the use of a preformed steel frame.

 

  FIGURE 35 PREFORMED steel frame on a commercial property (Public Domain Image © 2017)

  Again this system is set at a static angle, but is far lighter if the frame is bolted to the roof, rather than weighed down with concrete blocks. If these frames are to be bolted, then an allowance must be made for flashings so as to ensure the integrity of the roof’s waterproofing is maintained.

  A variation on this system, which is infinitely better is one which is adjustable. This type can therefore be set for the correct angle for the summer & winter solstices & any angle in between. Therefore, this system will maximise the output when the correct angle is maintained.

 

  FIGURE 36 ADJUSTABLE steel frame (Public Domain Image © 2017)

  This system can also be easily made by a competent DIY’er by simply cutting some angle iron to suitable lengths & connecting them together with wing-nuts & bolts (to allow for easy adjustment). Again as previously, an allowance must be made for incorporating flashings so as to maintain the roofs waterproofing.

  There is one more option available for flat roofs, & that is known as an East/West mounting. These can be used if for some reason facing the PV panels South is not possible, therefore it is possible to double up by having some facing East & some facing West.

 

Some installers have made claims that this setup can achieve electrical output up to 40% greater than a comparably sized South facing array. It is clear that the East/West arrangement will work well; however, it is unlikely to achieve the same output level as a South facing array & will never outperform a South facing array.

 

 

Figure 37 East/West mounting (Public Domain Image © 2017)

  It does however achieve a high power density as the number of panels in a given area can be increased, but the system uses twice the number of PV panels & twice the amount of racking. All costs are therefore doubled, but it is doubtful that you will reap double the rewards. From all the flat roof options that are available, the adjustable frame would offer a clear advantage, especially if they were constructed from scratch. This would ensure that the frame is purpose built for your needs & would be a simple project for any DIY’er.

  Ground mounted racking

 

ALL THE GROUND MOUNTED racking systems are the same as those for flat roofs. However, being ground based, there are infinite possibilities for a DIY’er. Figure 38 shows a DIY metal frame structure fixed to wooden piers.

 

  FIGURE 38 DIY METAL frame structure (Public Domain Image © 2017)

  Metal is not the only material suitable for a DIY frame build. Figure 39 shows a DIY frame which has been constructed from wood & is set on concrete pads with the aid of base anchor brackets.

 

  FIGURE 39 DIY WOODEN frame structure (Public Domain Image © 2017)

 

The obvious advantage of a DIY ground mounted array is that it can be made to your unique specifications & there can also be a significant cost saving over purchased mounting, however, care must be taken if you wish to benefit from angle adjustments, as this may reduce the solidity of the array.

  There is one more ground based mount that can be considered. This is a pole mounted ground mount. The principle works in exactly the same way as an aerial would on a roof mounted pole. That is being securely attached (bolted) to a pole.

 

  FIGURE 40 POLE MOUNT (Public Domain Image © 2017)

  The downside of this type of mount is that it is generally only suitable for one or two small or medium panels. Adding further panels would make the pole top heavy & it would also have a large surface area that would act as a sail in the wind. The probability of the wind uprooting the pole in

high wind could be a real possibility. Even with one or two small PV panels, the pole will need to be secured with a sizable concrete foundation. It is therefore unsuitable unless your site does not allow for a larger array. In that instance you would be forced to use multiple poles to set up numerous small panels until you reach the desired power output. If bracing is required to steady your poles, it would be advantageous to add guy wires, but this would take up rather a lot of ground space.

  Adjustable racking & tracking

 

HAVING A PV ARRAY THAT tracks the sun as it moves across the sky can increase your daily yield by up to 30% over & above the optimal static position. This means that every minute of the day, every day, the array will be at the optimal position to receive direct sunlight.

  These systems are quite expensive & therefore you will have to calculate whether this sort of system enhancement is justifiable. It may prove to be financially viable in the Sahara Desert, but perhaps not in the UK. Although at the very least, it will help your batteries on cloudy days & over the winter months.

  The most complex systems available on the market can move the panel, or array on two axis’; horizontally & vertically, thereby allowing the array to be perpendicular to the sun at all times as the sun moves across the sky every day. Due to economies of scale, these are far too expensive for small arrays (because a 30% increase on a small yield will be small). Therefore they are better suited for an array that is capable of producing 30Kw or more.

 

To understand how they work, consider that a fixed array should be set at the optimal position being at 12 noon. The yield increases up to this point & reduces afterwards (as can be seen in figure 21 in chapter 4). But the height of the sun in the sky varies throughout the year, therefore the tilt angle will typically be set at either of the solstice’s (highest & lowest point) or for the equinox (middle point between summer & winter). A single axis (vertical) tracker will track the height of the sun throughout the day as the sun rises & falls thereby maximising the output by matching itself to the height of the sun in the sky. However the sun moves from East to West throughout the day & therefore to maximise the output throughout the day, the array will also need to track the sun from East to West. Therefore a horizontal axis tracker will turn the array to directly face the sun throughout the day.

  Cheaper systems are available that only rotate on either the horizontal axis, or the vertical axis’ are available to purchase, but then the yield will never increase by 30%, so again you will have to calculate whether this sort of system enhancement is justifiable.

  Figure 41 shows how the most simple mount (pole mount) can be enhanced with tracking on both axis’.

 

  FIGURE 41 AXIS TRACKING on pole mount (Public Domain Image © 2017)

  These systems can therefore be easily thought of as tilt & as that is what their expensive components actually achieve.

  Single axis trackers

 

A SINGLE AXIS TRACKER will either tilt, or track, but generally they are horizontal single axis trackers (HSAT). These are constructed with a long horizontal tube which is supported on bearings mounted upon pylons or frames. The axis of the tube is on a North–South line. Panels are mounted upon the tube & the tube will rotate on its axis to track the motion of the Sun throughout the day. Figure 42 shows a HSAT array in Vellakoil, India.

 

 

Figure 42 HSAT array, Vellakoil, India (Vinay Kumar © 2014)

  This is somewhat different to a vertical axis tracker (VSAT), where the axis of rotation for a VSAT are vertical to the ground. They rotate from East to West over the course of the day. Layouts must consider variable shading to avoid unnecessary energy losses & to optimise the use of the land. Optimisation is limited due to the nature of the variable shading over the course of a year. VSAT’s typically have the face of the module oriented at an angle with respect to the axis of rotation. As a module tracks, it sweeps a cone that is rotationally symmetric around the axis of rotation.

  There are also tilted single axis trackers (TSAT). These can be fitted closer to their neighbours as they create less shadow allowing a higher density to be fitted in a smaller space.

  They typically have the face of the module oriented parallel to the axis of rotation. As a module tracks, it sweeps a cylinder that is rotationally symmetric around the axis of rotation. Figure 43 shows a TSAT array in Siziwangqi, China.

 

  Figure 43 TSAT array, Siziwanggi, China (Vinay Kumar © 2013)

  Dual axis trackers

 

DUAL AXIS TRACKERS have two degrees of freedom that act as the axis of rotation. These axis’ are typically normal to one another. The axis that is fixed with respect to the ground can be considered a primary axis. The axis that is referenced to the primary axis can be considered a secondary axis. There are several common types of dual axis trackers. Two of the most common types are known as tip-tilt dual axis trackers (TTDAT) & azimuth-altitude dual axis trackers (AADAT).

  TTDAT are so called because they are positioned on the top of a pole. The East–West rotation is driven by rotating the array around the top of the pole. On top of the rotating bearing is either a T or H shaped frame that provides vertical rotation to the panels & provides the main mounting points for the array. Layouts are very flexible as their shadows will not interfere with their neighbours. Normally trackers would have to be positioned at a fairly low density in order to avoid one tracker casting a shadow on its neighbours when the Sun is low in the sky, but this system can make up for this by tilting closer to horizontal to minimize the sun shading & therefore maximize the total power being collected. Figure 44 shows a TTDAT array in Siziwangqi, China.

 

  FIGURE 44 TTDAT Siziwanggi, China (Vinay Kumar © 2013)

  AADAT has its primary axis vertical to the ground. The secondary axis, often called elevation axis, is then typically normal to the primary axis. They are similar to tip-tilt systems in operation, but they differ in the way the array is rotated for daily tracking. Instead of rotating the array around the top of the pole, AADAT systems utilise a large ring mounted on the ground with the array mounted on a series of rollers. The main advantage of this arrangement is the weight of the array is distributed over a portion of the ring, which may be helpful if you are looking for an alternative to the TTDAT which is supported on a single pole. This allows AADAT to support much larger arrays. Unlike the TTDAT, however, the AADAT system cannot be placed closer together than the diameter of the ring, which may reduce the system density. Figure 45 shows an AADAT array in Toledo, Spain.

 

  FIGURE 45 AADAT ARRAY in Toledo, Spain (Public Domain Image © 2010)

  To drive or not to drive

 

THE CONTROL MECHANISMS that move the arrays can be either active or passive. Active trackers use motors & gear trains to direct the tracker as commanded by a controller which responds to the direction of the sun, whilst passive trackers use a low boiling point compressed gas fluid that is driven to one side or the other (by solar heat creating gas pressure) to cause the tracker to move in response to an imbalance. Electrically operated active trackers use two or more photosensors or photodiodes. These are the eyes of the system & with a small electrical circuit to switch on, or off the motor that moves the array. Passive trackers are similar to a hydraulic ram, which is controlled by the sun. As they warm up in the sunlight, it causes expansion of the internal gas & this causes it to move. They do take some time to react & therefore are not as precise as their active counterparts. Some even have solar reflectors to help speed up their response time. These systems do however suffer from the effects of wind chill causing the gas to contract & also physical

movement from the wind too. They are therefore inferior to the active control systems.

  System pros & cons

 

ALL OF THESE VARIOUS types of powered trackers have their own individual advantages & disadvantages, but generally, the pros & cons are as follows:

  Advantages

 

TRACKERS GENERATE MORE electricity than their stationary counterparts due to increased direct exposure to solar rays. This increase can be as much as 30%, but will depend on the geographic location of the installation.

  There are many different kinds of trackers as has been seen, but not all of which can be the perfect fit for your unique site conditions. Therefore, the size of your Installation, local weather, degree of latitude & electrical requirements are all important considerations that can influence the type of solar tracker best suited for your unique installation.

  Trackers do generate more electricity in the same amount of space needed for fixed-tilt systems, which make them ideal for optimising land usage.

  In certain states of the USA, some utility companies offer Time of Use (TOU) rate plans for solar power, which means the utility company will purchase the power generated during the peak time of the day at a higher rate (like a reverse Economy 7 price structure). In this case, it would be

beneficial to generate a greater amount of electricity during these peak times of the day. Therefore if the utility companies or the National Grid in the UK adopt a similar scheme, then using a tracking system could help maximize the energy gain during that peak time period.

  Advancements in technology & reliability in electronics & mechanics have reduced the long term maintenance concerns for many tracking systems.

  Disadvantages

 

SOLAR TRACKERS ARE more expensive than their stationary counterparts, due to the more complex technology & moving parts necessary for their operation.

  Even with advancements in reliability, there is more maintenance required than with a fixed array, though the quality of the solar tracker can play a role in how much & how often maintenance is needed. As trackers are a more complex systems when compared to fixed array’s, it means that more site preparation will be needed, which could include additional trenching for cables & also possibly upgrading the ground to accept the weight of the installation.

  Trackers may not be financially viable for your location, it is therefore important that a cost benefit analysis is made to see if these are worth installing.

  Trackers are designed for climates with little or no snow making them more viable for warmer climates. A fixed array will be more stable in harsher environments than any tracking system.

  Therefore trackers do sound like a good concept, but in reality they may be a burden. One final thing to consider is that if a tracking system can increase your yield by 20%, it would be cheaper to just increase a fixed array by 20% & at the same time remove all the risks associated with solar trackers. Taking a simple approach may therefore be the route that best suits a DIY installation.

  A simple approach

 

IT MAY THEREFORE SEEM logical to merely physically adjust an array yourself at various times of the year to get as near to the sweet spot angle as possible. Therefore if this is the case, ensure that you purchase or construct the racking to your array that enables adjustment.

  Obviously any panels fitted above or in a roof slope will be static & therefore you will be unable to adjust their angles. This is also true for the tub type & fixed steel frames. However, any frames of the angle iron type should be fully adjustable. If you opt for purchasing a system of this type, every manufactures system will be different to the next, but typically there is a latch that allows the angle to be adjusted into one of several predetermined positions, or a screw (or handle) that can be turned to increase or reduce the tilt angle. Even this manual adjustment several times a year can increase the yield by up to 7% & it also allows for a quick visual inspection at the same time.

  Cable management

 

THE ELECTRICAL CABLING joining the system components together can be thought of as being similar to blood veins in the human body. Instead of being the conduit for blood in a human body, they allow for the flow of electricity to the essential system elements in the installation. Therefore, it is important that the cables are protected from damage.

  Over time, the electrical cables will be subject to damage. This could be from mechanical damage from movement when the cables rub against something, such as if a cable is allowed to move in the wind & is continually rubbing against a wall or a frame. Cables can be damaged from the elements, such as the continual heat cycle when exposed to the sun & also UV damage from sunlight too. Insects, birds & vermin can also attack cabling, stripping the insulation. Cables can also be damaged by vandalism & even accidentally damaged. It is therefore imperative to protect the cables as much as possible.

  There are therefore several methods available that can be employed to do this.

  Firstly, it is important that the cabling you employ is trimmed to the correct length for the job at hand. Too much will allow the cabling to physically move & therefore trimming to length will mitigate this problem. Whichever system you decide to use, it is important that you always trim the cables to the correct length.

  Secondly, it is advisable to secure any loose cabling. This can be achieved by using cable ties of one sort or another, however these will all degrade when exposed to the sun’s UV light, therefore these will need to be replaced periodically, or alternatively it is possible to use a galvanised fixing band which will not degrade in sunlight.

  A better & more permanent solution would be use a conduit to house the cables. The first option would therefore be to use PVC trunking which can be easily cut to size to securely house the cables. Junction boxes & conduit boxes should be used to join various runs together & there are also numerous elbows & junctions available to help ensure the cable runs are completely sealed safely (without sharp turns) within the trunking, however this is more suitable for internal cable runs as PVC degrades in sunlight & PVC trunking can be eaten by rodents.

  A more robust system would be to use galvanised metal conduit externally. This system is completely robust & can withstand the rigours of the UK weather. You however may need to purchase a suitably sized tap & die set to make a suitably sized thread on the end of the channels if you have cut them to size, also any cuts that are made need to be treated as the metal will be exposed on the cut ends. Any scratches that are made to the components during installation would also need to be treated to inhibit any chance of corrosion.

  Any buried cable runs should be made with armoured cables so as to protect from any potential gardening/landscaping damage. It would also be advantageous to back fill any trenches with sand & to place electrical warning tape on top of the sand before backfilling the trench.

  The cabling on the installation can last many years & the installation will not operate without it. Therefore whichever method you adopt to house the cables will be money well spent as you should never need to replace the cables if you adopt the correct method to protect the cables, cable runs & joints. Ensure that all cables are well protected from all hazards.

  Back up power

  THERE MAY BE OCCASIONS when there is not enough sun, or not enough wind to adequately charge your batteries. A generator will therefore fill any shortfalls in any deficit suffered by your PV &/or wind turbine system, & therefore keep the lights on.

  Hospitals & other large buildings have diesel generators that are designed to cut in when there are power cuts. You can use the same concept for your system, but on a much smaller scale.

  The cost need not be excessive for a small domestic generator & many can be purchased for just a few hundred pounds. There are numerous sizes with various levels of output available. Figure 46 shows one small inexpensive Chinese generator with a generic design that is currently on the market.

 

 

FIGURE 46 INEXPENSIVE Chinese generator (Public Domain Image © 2017)

  These generators are always listed online with their designed output level. Therefore you could opt for a 1Kw model, 3Kw, 5Kw etc.. The bigger the output, the greater the price. Also, these units are not designed to be permanently left outside, but it is unsafe to leave them working indoors, therefore, it may be prudent to house the generator in a small shed. Also, as all internal combustion engines need clean air to function & need to expel spent air through the exhaust, it would be sensible therefore to create a fireproof exhaust that exits outside the shed & a fireproof air intake to feed the generator.

  These generators also generate a lot of noise, even the quieter ones. They are after all small motorbike engines. It would therefore be sensible to soundproof the small shed to minimise the noise level for yourself & your neighbours. Vibrations can also be a problem, so it would be beneficial to create a rubber mount to sit the generator on. Whatever soundproofing & vibration proofing you use will benefit both you & your neighbours. Running costs are set to rise for petrol & diesel, but that is controlled by global demand & out of your control. One thing is certain, if you suffer from a few days with only a little sunshine & very little wind, then you may be glad that you installed a generator to top up the power to your batteries. Also, it will wait until it is needed, so you can plug it in as & when it’s needed, then turn it off again when it is not needed. However, a word of warning, never fully charge your batteries from the generator as whichever batteries you purchase will be designed to be charged by the PV or the wind turbine & if you want the generator to kick-in automatically when the batteries drop below a certain level, then you will need to include an automatic transfer switch (ATS) & an automatic starter.

These will start the generator when specific programmed conditions exist & switch the generator on, or off.

  Your inverter & generator will also need to be compatible, as the inverter & ATS will need to be speaking the same language for it to operate as you intend. Also, in 1900 Rudulf Diesel invented the diesel engine to run off peanut oil, so if diesel is in short supply (such as after 2040 when the UK & EEC intends to ban sales of petrol & diesel vehicles), then with little or no modification, the diesel generator could be run off waste cooking oil &/or renewable bio oils.

  The main problem with waste cooking oil (WVO) is that it often contains cooking waste & water. It therefore needs to be filtered to clean the oil. WVO also has a different viscosity to regular diesel (RDO) & biodiesel (BDO); therefore the diesel engine/generator will not run with this oil straight after filtration. Biodiesel will run without modification because it has already been chemically treated to make its viscosity the same as regular diesel. Straight vegetable oil (SVO) also needs to be treated to make it the same viscosity as RDO. To make filtered WVO & SVO the same viscosity as RDO, it needs to be heated to achieve the desired level of viscosity which is the same viscosity as RDO. Most individuals who run generators & vehicles from WVO & SVO use the same method. They have two tanks, one for WVO/SVO with a heating element & another for RDO. When the WVO/SVO reaches the desired viscosity, they switch from the RDO tank to the WVO/SVO tank. Alternatively, the WVO & SVO can be treated by a process called transesterification, a fairly simple process that uses lye to remove the coagulating properties from the oils. The by product of biodiesel processing is just glycerine, which is used in soaps & other harmless products. Therefore this process will need to be

undertaken before the oil is placed in the fuel tank. Most people who use this method undertake the entire process it in their garage or outbuilding.

  The viscosity problem is caused because the majority of diesel engines/generators use an injector pump to feed the fuel into the engine. Older diesel generators used a positive displacement fuel pump which supplied fuel continuously to the injectors; therefore the viscosity of the fuel was never a problem.

  If new generators were to be manufactured with positive displacement fuel pumps, then it would be possible to run clean WVO, RDO, SVO & BDO without any modification to the oils, or needing to pre heat it. This would make clean efficient fuel a reality to everyone. In the USA, ‘Affordable Power’ has seen this gap in the market & has manufactured such a generator. It is called the 2-71 Detroit Diesel. This generator will run without any modifications. Currently, many restaurants & café’s are happy for people to remove their WVO either for free or for a small charge as they have to pay for someone to remove it. Therefore there is a clean free (or low cost) energy source that can be utilised to generate you electricity that you can use or sell to the National Grid. Also, this fuel source is carbon neutral (as it does not emit any more carbon than it absorbed when it was growing as a plant), The exhaust emissions are cleaner than RDO, it is made from renewable sources, WVO can be obtained locally to you as there will be restaurants & café’s near to you & it will stop the potential of the oil from going into landfill.

  Currently this source of energy is untaxed; therefore the government is keeping quiet about it rather than promoting it as a clean energy source. There may however come a point when the government decides to tax it. Until they do, it makes excellent fiscal sense to utilise it. If you do make

suitable fuel, it would be easy to take the next step & convert a diesel powered car to run off WVO, SVO & BDO, rather than RDO.

  Building integrated photovoltaic technologies

  THIS IS WHEN ELEMENTS of the building structure are constructed with photovoltaic materials so that they form part of the building structure, rather than being independent elements fixed on to the building structure.

  This is technically known as building-integrated photovoltaic’s (BIPV). Elements can include glazing, roofs, skylights & even façades. They do tend to be mostly used in new build structures, but can also be retro-fitted to existing structures. This is technically known as building-applied photovoltaic’s  (BAPV). The main advantage of this using this type of PV is that there is an obvious cost saving as materials are not doubled up. For instance, the panel are used in place of glazing, rather than having glazing & have panels fixed over them.

  Both BIPV & BAPV are the fastest growing part of the PV market. Elon who created the Tesla car & energy company is set to sell PV roof tiles in the UK & EEC that look very much like traditional roof tiles.

  PV roof tiles

 

PV ROOF TILES WILL therefore blend in very well to roof slopes & are consequently less noticeable when compared to traditional PV panels. Tesla have announced they will start selling their PV tiles in the UK at some point in 2018 & currently have the following four tile patterns on their website.

  FIGURE 47 TESLA SOLAR tiles (Tesla solar roof tiles © 2017)

  The tiles work by sandwiching solar cells inside tempered glass. They are designed to look like regular roof tiles when viewed from street level, but the cells are clearly visible when viewing the tiles from above. It works the same way as polarising glass over the cell, blocking light from some angles, but allowing a clear path for the light from other angles. Tesla claim that their tiles will not degrade over time & even sell matching non PV tiles, as the PV tiles can not be cut & they do not expect anyone to cover 100% of a roof in these tiles, but anticipate just 40 – 70%. They also claim to have a 30 year power warranty, but PV tiles like these are not a new invention as they were developed by a Dutch firm called Zep BV in 2012.

  The main drawbacks for this sort of system is that they use a huge amount of cabling (each tile needs to be cabled into the system), this is very expensive & can lead to heat building up in the roof void. As such, PV roof tiles have been blamed for causing fires in the USA. Also, Tesla tiles are reported to work only with the Tesla batteries, therefore an individual will not have any design control as they operate a ‘one size fits all’ approach. Another big drawback for PV tiles are they actually contain a smaller percentage of solar cell per when compared to regular PV modules, therefore the anticipated output of the PV tiles will always be lower than the PV modules. PV tiles are also far more expensive than PV panels (approximately three times the cost). Due to these drawbacks, PV tiles have not seen a large demand & therefore forms only a tiny part of the PV market.

  However, any Local Authority planning department are no doubt going to prefer these tiles to PV panels, therefore there will come a point when it will become impossible to legally install PV panels in the UK. It would seem credible therefore that there will only be a limited time to install a rooftop PV array before the planners insist on solar roof tiles being used on all rooftop installations.

  Metal roofs are also becoming popular in some areas. Even formed metal profiles that look like traditional roof tiles. As such PV modules are also now being manufactured that look like profiled metal sheeting.

  PV glazing

 

PV GLASS USES THE SAME technology as the standard PV panels, except it utilises an extremely thin film PV that is so thin it appears almost transparent. This is typically spayed onto the glass or printed. This process makes the PV enabled sheet of glass very efficient, as such it will function where traditional PV panels will not, such as on a vertical face of a building. The process also adds to the thermal efficiency of the glazing panel. As such, PV enabled double glazing can thermally perform as well as traditional triple glazing, thereby helping to reduce the thermal gains & thermal looses.

  This could make PV glass a viable option in homes due to its thermal efficiency alone. Early versions of this glass had an orange tint, but now it is virtually transparent. Currently this glass is available various thicknesses, sizes, colours & different levels of transparency. It works in all weather conditions & even in low light, so it is ideal for the UK’s climate. Currently, it is more expensive than traditional glass (40% more

expensive), therefore when the price falls to compete with regular glass, it will no doubt become widely adopted & may even replace traditional glass completely.

 

 

Figure 48 PV glass (Public Domain Image © 2017)

  In its current form, it is suitable for use in glazing, cladding, canopies, façades & curtain walling. When the price reduces, the availability will increase & then so too will the take up. Currently, of the glass being manufactured in the world, 2% is used for PV’s, whilst 80% for glazing. It is therefore clear that PV glazing has a huge market share which it can expand into. In 2013, Oxford University released their findings on using perovskite (an oxide used to manufacture ceramic semiconductors) in PV glazing, where they claimed an efficiency of 20%. They are currently working on making & marketing their ‘improved’ version of PV glazing. In the USA, Michigan State University has developed a transparent solar concentrator which will produce electricity when placed over a window (but presently with only a 1% efficiency rating), therefore the race to produce a cheap, efficient product is currently ongoing & the next few years should see some exciting developments.

  BIPV

  MANY LOCATIONS WORLDWIDE have integrated PV panels installed as carports. Figure 49 shows a solar parking canopy which has been installed at the Autonomous University of Madrid (UAM), in Spain.

 

 

Figure 49 Solar parking canopy at University of Madrid (UAM), Spain (Hanjin © 2013)

  A similar PV system has also been used to give a visually distinct appearance to the façade of the Social Services Centre Jose Villarreal, Madrid, Spain.

 

  Figure 50 PV Façade at the Social Services Centre Jose Villarreal, Madrid, Spain (Hanjin © 2013)

  Some countries offer subsidies for BIPV’s in addition to existing feed-in tariffs. Since July 2006 France has offered the highest incentive for any

BIPV. It is equal to an extra premium of EUR 0.25/kWh paid in addition to the 0.30/kWh for PV systems.

  The motor industry is also currently researching built in PV’s, as their aim is to incorporate PV’s into a vehicle’s roof, bonnet & boot to help power both the vehicle & the electrical devices used onboard, therefore future developments could also come from the vehicle industry & will be transferred & incorporated in building technology.

Chapter 6 - Legislation in the UK

    IEC 62446

  IN THE UK, THE LEGISLATION that specifies the minimum requirements for all PV systems, commissioning, testing & inspections is ‘IEC 62446: 2009 Grid connected PV systems’.

  After the installation of a solar electrical system, any subsequent building or electrical works within the vicinity of the PV array are likely to impact the system. Also the ownership of a building with such a system will also change. As a result‚ this standard recognises that only by providing adequate documentation ‘at the outset’ can the long term performance & safety of the PV system be ensured.

  This standard therefore sets out the information & documentation that should be provided to the consumer following the installation of a PV installation & also the initial (& periodic) electrical inspections & required testing schedule.

  The standard sets out measures to ensure that:

  The PV panels & electrical supply connections have been wired up correctly. That the electrical insulation is adequate. The protective earth connection is correct.

There has been no damage to cables during installation.

  This international standard was published in March 2009. When voting was taken on this standard, all member countries voted in favour, including the UK, USA, Russia, China & many other major contributors. Since then it has subsequently been adopted as a European EN in the EEC & is now regarded as a significant contribution to improving the quality & safety of all PV installations.

  In the UK, the ‘British Microgeneration Certification Scheme’ has adopted the principles of IEC 62446 as the basis for its testing & documentation regime. As a result, the fundamentals of this standard are effectively enforced because no feed-in tariff will be paid to any PV owner unless their installation has been installed by an MCS accredited installer.

  The emphasis in this standard is on documentation & this is in effect the evidence used to demonstrate that appropriate precautions &/or tests were undertaken prior to the handing over of a PV installation to the property owner. Such information not only provides evidence to the consumer that work has been performed correctly, but it also acts as a check list to an installer & ensures that best practice is followed with the work that has been undertaken.

  When it comes to installing a domestic installation, the UK government are keen to allow PV installations & solar panels. Partially to appease the EEC & UN, but also partly to appear to have ‘green’ credentials. Therefore they have relaxed legislation to make this possible.

 

Planning permission – Domestic PV’s

  THE KEY DOCUMENT THAT relates to planning permission for any domestic PV installation in England is The Town & Country Planning (General Permitted Development) (Amendment) (England) Order This amendment has categorised PV installations of residential PV or solar thermal systems as a ‘permitted development’, which means that the installation does not require planning permission provided that electrical safety requirements set out by the ‘Building Regulations’ are met & that it meets certain other requirements. Those other requirements are as follows.

  Roof mounted PV installations on a house

 

THE PV ARRAY DOES NOT protrude more than 200mm above the roof line.

  The PV array must not be higher than the highest part of the roof (excluding chimneys).

  If sited in a conservation area or world heritage site, the PV array must not face onto or be visible from the highway.

  As far as possible, the array must be sited to minimise the effect on the external appearance of the building.

  A PV installation cannot exceed 1 megawatt under permitted development on any rooftop installation.

 

Roof mounted PV installations on garages, sheds, stables & other  outbuildings IF IT IS ASSUMED THAT the outbuildings are already constructed & they are located within the curtilage of a residential property such as barns, garages, sheds & other outbuildings, the installation of any PV installation is classified as 'permitted development', provided that the same conditions are met as those applicable to houses.

  Ground mounted PV installations

 

THE INSTALLATION OF a ground mounted PV installation is covered by ‘permitted development’, only when the following points are adhered to:

  The PV array must not be over 4m in height.

  The PV array must be more than 5m from the property boundary.

  The size of the PV array must not exceed (which equates to no more than 5 large solar panels). Anything greater than will require planning permission.

  If sited in a conservation area or world heritage site, the PV array must not face onto or be visible from the highway.

  PV canopies & PV carport installations

 

THESE MAY, OR MAY NOT fall under ‘permitted development’. It depends on the nature & size of the installation & the local authority.

  Generally, there are some pointers.

  Any carport or canopy must be open on at least two sides.

  The carport or canopy must not project further than the front of the house.

  The carport or canopy must not exceed

  The carport or canopy must not be higher than 4m at its highest point.

  The carport or canopy must not be wider than half the width of the original house.

  The carport or canopy must be used exclusively for domestic use.

  The carport or canopy must not take up more than 50% of the available outside space.

  The PV installation cannot exceed 1 megawatt under permitted development on any rooftop installation.

  It is therefore advisable to contact your local authority’s planning department before commissioning any carport/canopy installation.

  Planning permission  – commercial PV’s

 

DEVELOPMENT ‘ rights were applied to PV installations installed on commercial, industrial & agricultural roof spaces in England on the 6th April 2012. The legislation that relates to planning permission  for PV installations on these premises is The Town & Country Planning (General Permitted Development) (Amendment) (England) Order

  Any such installation should fall into the category of ‘Permitted development’ provided that electrical safety requirements set out by the ‘Building Regulations’ are met & that it meets certain other requirements. Those other requirements are as follows.

  Roofs on commercial buildings

 

ON A PITCHED ROOF, the highest part of the PV array must not be more than 200mm above the roof line.

  On a flat roof, the highest part of the PV array must not be more than 1m above the highest part of the roof (excluding any chimneys).

  The PV array must be sited more than 1m from the edge of the roof.

  As far as possible, the array must be sited to minimise the effect on the external appearance of the building.

  The PV installation cannot exceed 1 megawatt under permitted development on any rooftop installation.

  Ground mounted installations on commercial, agricultural or industrial

  land.

THE INSTALLATION WILL only fall within the scope of ‘permitted development’ when the following criteria are met.

  The PV array must not be over 4m in height.

  The PV array must be more than 5m from the property boundary.

  The size of the PV array must not exceed (which equates to no more than 5 large solar panels). Anything greater than will require planning permission.

  If sited in a conservation area or world heritage site, the PV array must not face onto or be visible from the highway.

  A commercial PV array will in the majority of cases be far greater than planning permission would seem to be a requirement in the majority of installations.

  Commercial, agricultural or industrial canopies & PV carport installations

 

PLANNING PERMISSION  required before installing PV systems on, or building carports, canopies, smoking shelters or other PV mounting structures that will form part of commercial, industrial or agricultural buildings.

  A PV installation cannot exceed 1 megawatt under permitted development on any rooftop installation.

 

What if Planning permission is required

 

THE NEED TO GET PLANNING permission before installing any PV system should not put anyone off from installing such a system. The installation of PV technology is generally well understood & welcomed by most local authorities but understandably some local authorities are more autocratic when implementing legislation & any protection that needs to considered. The recent changes to 'permitted development rights' are proof of the positive approach taken by central government with regards to installing renewables. The local authorities are therefore forced to follow where they are led.

  Any planning application with a sympathetic & well designed system that takes account the wider environmental impact & goes to great length to minimise any negative effects created by an installation is likely to be treated favourably. Most local authorities have their own guidance about installing renewables available on their websites & many have implemented local plans to promote the concept of renewables in their areas.

  Wherever possible the local planning department will encourage efficient land use. As such, the use of brown field sites are encouraged, but when Greenfield or agricultural land is put forward, they will encourage dual uses, such as PV installations coupled with grazing animals &/or encouraging biodiversity in the area.

  Although most PV instillations are designed for many years use, many local planners wish to see that the proposed area could be reinstated after decommissioning. Therefore they would prefer to see temporary buildings & infrastructure to help facilitate this.

  When it comes to the landscape in general, the planners are supposed to take a standpoint on preserving the views in the countryside & protecting any heritage assets. Therefore the visual impact of any PV installation will be considered.

  They describe a ‘heritage asset’ as a series of buildings, a landscape, a view, an archaeological site, or just about anything they decide. For their purposes a heritage asset does not need to be a legally protected asset such as a conservation area. It could even be anything of special interest, of national or local importance or even anything that could offer value which could be negatively affected by the proposed installation. The cumulative effect of the number of PV installations in an area will also be of consideration.

  Although it is advisable to involve any planners &/or conservation officers from the local authority at the earliest possible stage, it is the authors experience that they are obstinate, unhelpful bureaucrats who are fantasists & do not understand how things operate in the real world. They have unfortunately been given powers that they do not deserve or are able to wield in a fair or consistent manner. They are unfortunately able operate with impunity. You must however try to work with them.

  Scotland, Wales & Northern Ireland

 

IN SCOTLAND, THERE are additional rules that require planning permission. This is covered in the Town & Country Planning (General Permitted Development) (Domestic Microgeneration) (Scotland) Amendment Order It is therefore prudent to check with the relevant local

authority before undertaking any installation in Scotland as there are slight differences to the legislation covering England.

  In Wales, it is similar to England but covered by the Town & Country Planning (General Permitted Development) (Amendment) (Wales) Order It is therefore prudent to check with the relevant local authority before undertaking any installation in Wales as there are slight differences to the legislation covering England.

  In Northern Ireland, the legislation relating to PV installations changed in 2013 & most recently again with the Planning (General Permitted Development) Order (Northern Ireland) It is therefore prudent to check with the relevant local authority before undertaking any installation in Northern Ireland as there are some differences to the legislation covering England.

  The Building Regulations – PV’s

  WHETHER OR NOT PLANNING permission falls within planning permission’s ‘permitted development’ or not, any installation is subject to ‘Building Regulations’. This should be thought of as minimum design & build standards that ensure (as far as reasonably practicably) that the proposed work is of a minimum standard. For instance, if you intend to install a roof mounted system, you are required to prove that the roof structure is capable of supporting the installation. If the proposed roof is not substantial enough, then you will have to provide a method to bolster the strength of the structure to support the additional load.

 

Any PV installation must therefore ‘comply’ with the requirements of the ‘Building Regulations’. Again it involves liaising with the local authority, but in this instance building control, who are more amenable & approachable than the planners. It should be possible to quickly build a good working relationship with those at building control. This is because the building regulations are based on quantifiable & tangible facts & figures. This differs from the planners who work on whims & opinions.

  The ‘Building Regulations’ make the person undertaking the work responsible for compliance. If you intend to undertake the construction of a PV installation personally, then you are the individual who must ensure that ‘all works are in compliance’.

  In England & Wales the ‘Building Regulations’ are covered by the ‘approved of the Building Regulations In Scotland it is covered by The Building Regulations (Scotland) & in Northern Ireland by The Building Regulations (Northern Ireland)

  This book covers Building Regulations in England & Wales, it is therefore important to check with the applicable legislation for your area if you intend to undertake work outside of England & Wales.

  The Building Regulations are split into numerous parts:

  Approved Document A – Structure Approved Document B1 – Fire Safety (domestic) Approved Document B2 – Fire Safety Approved Document C – Moisture Approved Document D – Toxic Substances

Approved Document E – Sound Approved Document F – Ventilation Approved Document G – Sanitation & Hot Water Approved Document H – Drainage & Waste Disposal Approved Document J – Combustion Appliances Approved Document K – Protection from falling Approved Document L – Conservation of Fuel & Power Approved Document M – Access & Use of buildings Approved Document P – Electrical Safety (domestic) Approved Document Q – Security in Dwellings Approved Document R – High Speed Electronic Communications Approved Document 7 – Material & Workmanship

  Not all the above will be relevant or applicable, but as building control are responsible for ensuring compliance with the Building Regulations are met, & each local authority interpret the legislation differently. One council may state that the works are exempt, another may not. It is therefore important to liaise directly with building control & keep any correspondence that you receive.

  However, the following sections may be applicable & should form a basis for any calculated design proposals.

  Part A – The roof strength may need to be upgraded due to increased loading. The effect of wind lift on an adapted roof &/or PV panels as PV panels can act as wind-suction collectors & generate a huge amount of uplift. The proposed sizes of holes for cabling. Certification of proposed materials.

 

Part B – Fire risk on PV installation due to possible over loading &/or short circuiting. Fire resistance to roof coverings, such as PV panels, PV tiles or slates. Fire proofing to cable penetrations through the building fabric. Ventilation to any equipment that produces heat, such as PV modules, cabling, inverters etc.. Certification of proposed materials.

  Part C – Proposed method to prevent the ingress of moisture penetration into the building fabric including walls & roof coverings.

  Part D – Remedy for potential spill of chemicals from batteries. Intended procedure for disposal of spent batteries.

  Part E – Remedy to the transmission of sound into the building through cabling.

  Part F – Correct positioning of ventilation for the heat producing components.

  Part K – Method of safe installation of all components when positioned at a height. Method of safe access & egress for maintenance of installation components. Correct selection, construction & use of access equipment such as scaffolding.

  Part L - A PV installation is recognised in many applications as a way of conserving fuel & power, because it involves generating energy in an environmentally-friendly way, rather than consuming it from the fossil fuel grid supplies.

 

Part M – Accessibility & placement of equipment to ensure easy access to inverters, monitors, fuse boxes, isolators etc..

  Part P – Use of the correct size & position of cabling & connections. Bonding & earthing of components. Protection from damage by the ingress of water & dust, animal damage & also damage from humans from either an accidental source or vandalism. Methods to isolate system components. Correct selection & use of protective devices such as RCDs, fuses & isolators Labelling & warning signage. Certification of proposed materials.

  Part P is also applicable to anything in or attached to a dwelling, therefore a shed in a garden will apply, as will an outhouse or outbuilding, even greenhouses. It is even applicable to the land that is attached to a building. It is therefore also applicable to all DIY work.

  It should therefore be obvious that there will be considerable work involved with designing a system that is safe & complies with current legislation. Your local authority are there to advise & give guidance, therefore it would be worth liaising with them to save time, money & effort on aborted designs.

  There is a Competent Person Scheme (CPS) that was introduced in the Building Regulations that allows approved installers to self certify their works & designs. All relevant CPS are listed on the ‘Department for Communities & Local Government’ If you adopt to use one of the CPS installers, to undertake work covered by Part A, C & P, building control would not involve themselves unless they believed that any the works were in contravention of the regulations. If they did find any

contravention, then it would be down to the local authority to decide on the remedy (enforcement action).

  If you do opt to use a CPS installer, all other parts of the works will require Building Regulations approval.

  Under Approved Document A, PV panels must comply with Building Regulations & therefore installation is covered by ‘Installation of a Controlled Service or Fitting’ & also it is a ‘Material Alteration’ if any structural alterations are needed on a structure to support the weight of the PV panels. To expand on that point, most roofs are designed to support & PV panels weigh approximately therefore if the additional increases the load on the roof by more than 15%, then it is classed as a material alteration, if it is less than 15% then it is not a material alteration.

  However, it is better to always check with the local authority so as to mitigate the chances of being served with enforcement action by the local authority.

  British Standards

  THERE ARE MANY BRITISH Standards (BS) & International Standards (ISO) that UK Legislation refers to. One of these relates to ‘Cable ratings & Locations’.

  BS7671:2008 & Amendment 3 (2015)

 

THE IET HAVE PRODUCED a handy guide to BS7671:2008 & Amendment 3 2015. It covers cable sizes & they are placed together &

grouped into tables concerning where they can go & which current they can carry. The mixture of these two things is called a Method & there are 7 methods. Their titles are:

  Method A - Enclosed in conduit in an insulated wall. Method B - Enclosed in conduit or trunking on a wall. Method C - Clipped direct. Method 100 - In contact with plasterboard, ceiling or joists, covered by thermal insulation not exceeding 100mm. Method 101 - In contact with plasterboard, ceiling or joists, covered by thermal insulation exceeding 100mm. Method 102 - In a stud wall with thermal insulation with cable touching the wall. Method 103 - Surrounded by thermal insulation including in a stud wall with thermal insulation with cable not touching the wall.

  There are numerous other BS & ISO’s that are applicable to solar energy systems. As such there are far too many to list within this book. If further information is required, then an internet search with the topic (such as photovoltaic panels) & the words ‘British Standards’, or ‘International Standards Organisation’ will forward you in the right direction. If however you do wish to read them in full, you may have to pay.

  Further reading on legislation

  THE FOLLOWING DOCUMENTS may be worth researching if further information is required on planning or building regulations.

 

The Town & Country Planning (General Permitted Development) (Amendment) (England) Order The Town & Country Planning (General Permitted Development) (Amendment) (England) Order ‘Planning Policy Guidance 2 (PPG2): Green Belts’ was superseded by the National Planning Policy ‘Planning Policy Statement 7 (PPS7): Sustainable Development in Rural Areas. By Design: Urban Design in the planning system, towards better practice’ was also superseded by the National Planning Policy as was ‘Planning Policy Statement 22 (PPS22): Renewable & ‘Planning practice guidance for renewable & low carbon energy (July

Chapter 7 - The system design

    BEFORE YOU CAN DESIGN your system, you will need to understand what uses electricity in your home & exactly how much it uses. This is because if you design a small system but you actually need a much larger system, the system simply will not be able to cope with the demands you place upon it.

  It is therefore essential that each & every item of electrical equipment in your home is looked at to determine just how power hungry it actually is. To make an accurate measurement use a plug in a kill-a-watt power meter. They are available to purchase online & typically range in price between £10 - £20 (see chapter 10 for more information).

  These meters will inform you on the exact wattage for whichever appliance you are testing. You can then double check your readings with the designed wattage which should be evident on the appliance nameplate which you often find on the rear (or bottom) of the appliance.

  Also, if you are replacing any electrical items, it would be advisable to replace them with more energy efficient models, thereby lowering the overall running cost & the ultimate load on your system. For instance, it will be cheaper to install & use energy efficient lighting at your property rather than install a PV/wind turbine system to power inefficient lighting. The same is true for all appliances that you plan to use at your property.

 

Calculating your load

  CONSIDER THIS. IF THERE are 10 incandescent light bulbs in your home where 3 are rated at 100w & 7 are rated at 60w then this is a total of 720w. If these are replaced with their equivalent in energy efficient bulbs, then that would equate to 3 at 55w & 7 at 30w, which is a total of 375w, so there is a huge saving already, but if the incandescent lighting was replaced by LED lighting, this would equate to 3 at 20w & 7 at 7w which works out to 109w. Therefore there is an instant saving just by switching light bulbs. It is more cost effective to do this than pay several thousand pounds to build an energy system to provide power to the lighting; therefore the most cost effective system is the smallest system that will meet your needs.

  However, lighting is not the only thing in your home that use electricity, therefore a detailed study will have to be made so that you know exactly what is using electricity & just how much. This may sound like a simple task, but also consider that it is highly unlikely every electrical appliance in your home will be in operation at the same time. If for instance you look at a kitchen, chances are that the light will be on in the evening, as well as the cooker & hob. The fridge & freezer will be on 24/7, but smaller appliances such as a mixer or food processor will only be used for a short duration & probably not at the same time as the oven, but perhaps a radio may be on whilst someone is cooking in the kitchen. However, for the purpose of this example, it will be assumed that each of these electrical appliances are all switched on at the same time.

  If it is assumed that there are 3 energy efficient bulbs which are equivalent to 60w bulbs, that would equate to 3 x 30w (90w). The fan oven can be

assumed to be 2780w (but not running at full power, so assume 1700w) & an electric hob which is burning two rings at 7400w (two rings would be 3700w), a fridge at 1480w & a freezer at 1840w. A food processor may be rated at 750w & a mixer at 250w then the radio at 7w. If it is assumed that each & every one of these are all on for one hour (to make the example easier), the total would be:

  90 + 1700 + 3700 + 1480 + 1840 + 750 + 250 + 7

  = 9817w or 9.8kW

  This example is over one hour so it is 9.8kW/h

  This is a lot of electricity for one room over one hour. Also, another factor to consider is many appliances (the ones with electric motors such as hairdryers, food mixers, electric drills, circular saws etc.) may be rated at a particular wattage, but that is how much electricity is needed to keep them running. To get them started & to get them up to speed they could require twice or three times their ‘rated power consumption’, therefore this ‘in-rush current’ will need to be measured. To do this, you will need a clamp meter or multimeter that has a surge function (see chapter 10 for more information). Until you know what the actual power need is for that particular electrical appliance, you will never be able to accurately predict the needed electricity supply.

  There is another point to be aware of. Your electrical items will also use a percentage of their ‘rated power’ when they are on standby. You no doubt knew that already, but did you know exactly how much this actually costs in electrical energy? Some items can use 90% of their rated power, some

80%, some 75% etc., some can use a lot less, perhaps 5%. As an example, if you consider a 100w television using 50% on standby, it will be using 50w when it is standby mode. If the television is switched on & used for 6 hours a day, that would be 600w used, now add the standby time for the remainder of the day 18 hours at 50w is 900w. Add them together (900w + 600w) to get the daily electrical demand for the television (1500w aka 1.5kW). Standby power can potentially consume a lot of power & this is notoriously difficult to estimate accurately. The best method is to use a kill-a-watt power meter to measure exactly how much power the appliance is using when it is in standby (see chapter 10 for more information on the kill-a-watt meter).

  The next step is to create an inventory for your entire house, working out the exact wattage each item requires (remember that the wattage should be listed on the rear or base of every appliance or even in the manual. If you cannot find it, check online). If you have a kill-a-watt power meter, it would be advantageous to use that to note the ‘in-rush current’ for all the appliances that have motors. Do not forget to include your hot water pump, even if you have gas central heating, the pump will be an electric pump.

  Also, decide what is necessary in your home. Perhaps there is a hair dryer (or some other item) that nobody uses. This is an ideal time to sell it, bin it or take it to the charity shop.

  After all this, you should see that the list you have created is very long. The advice here is to now decide what is vitally important, what is not. For instance, there may be two mobile phones in the house, these would no doubt be very important items for their users & they would not wish to be without them. These would therefore be important items & should be

prioritised. If you have Christmas tree lights, these would be very low priority compared to the mobile phones. Given a choice, who would rank their Christmas tree lights over their phone? Those lights are therefore consigned to being of no importance.

  The next step is to take the time & see just how long each of the important items are being used for every day or every week. You will therefore be able to accurately work out your annual energy use & demands.

  After working through your inventory, you should now have the wattage for every item in your house, know exactly how long they are used for every month & have labelled each of them all as being either priority items or non priority items. This is where you will be making two charts which will enable you to compare how much energy is currently being used, with a realistic minimum figure that you could use.

  The following chart is a reduced list as it contains only items that are considered important & is being used here as an example. However, your list should ideally follow the same format, but only contain items that are deemed important by you.

 

 

From this list, it should be obvious that just running the electrical items that are important, would still require almost 10kW/h, therefore that would be the minimum size system that would be required to meet the

needs for the above list. It is also advantageous to include some spare capacity in case another appliance is purchased & added to the list.

  However, a system to meet a modest need of 10kW/h will never operate at 100%, therefore a 15kW, or better still a 20kW system should allow for any unfavourable weather, system inefficiencies & if there is a surplus of electricity at the end of each day, it could be sold off to the National Grid to make a little money.

  System costs

  A HOME ENERGY SYSTEM that would meet these modest needs will never be cheap. It will require a considerable investment. If you have calculated your important list of items, then you will now know what size system you need.

  In the UK, the cost of a 10kW PV system (if you opted to have an installer construct the system) would be in the region of £12,500, but a smaller system would cost less.

 

 

A larger system would cost considerably more. Obviously, a 10kW PV system will never meet the requirements in the example.

  As was seen previously, to be eligible for any payments under the governmental FIT’s, you will need to buy a suitable systems from an MCS approved contractor to be instantly eligible for payments. A DIY system will have to receive certification & then apply through the Roo-FIT scheme. Obviously if you constructed your own PV system yourself as a

DIY build, you would make considerable savings (you could half the costs listed in this chapter), but if you want a system that has a guarantee & warranty which is instantly eligible for FIT’s payments, then you will be forced to use an MCS approved contractor & a MCS approved system. However, the choice is down to the individual.

  Payback

  FOR THE EXAMPLE SYSTEM listed here, it could cost £12,500 as has been seen earlier in this chapter, but just how long would it take to recuperate this sizeable investment? That is a very difficult question to answer as there are so many variables & every system is unique. Also, energy costs fluctuate & the cost of the system components are set to fall. Everyone’s usage levels are different, the FIT’s tariff fluctuates due to governmental initiatives & the general cost of energy is set to rise considerably in coming years.

  Therefore it is only possible to give a general idea, but it will always be changing as the variables always change & so do the targets. You should therefore recalculate your findings annually if you wish to have a reasonably accurate set of figures.

  You should know how much you pay for your electricity (if not, it is printed on your electricity bill) & if you followed the exercise earlier in this chapter you should know how much electricity your household appliances are using. You can therefore see how much your energy expenditure is costing you every day.

  Any system you install will never be 100% efficient & therefore a prediction on the expected output is impossible, but after you have installed any system, you can deduct what you’ve generated from what

you would’ve bought from your energy supplier. That will be a cost saving every month. Also, if you are eligible for the FIT’s payments, you can include that too.

  The savings you have made to your energy bills will add up & eventually there will be a point in time when these payments will have covered the cost of your energy system & then will be making money as the savings & income will be pure profit.

  Therefore you are the only person who can accurately calculate your potential savings. However, here is a simple payback periods for a typical system. Currently, it takes approximately 8 - 10 years to start making a profit on PV systems.

  This payback period is completely generalised, but as the cost of electricity is only going to get more expensive & at the same time the demand will also increase, the likelihood of power cuts are now looming large on the horizon. Therefore, the payback period will clearly reduce over the coming years (due to the increasing cost of electricity) but you will also have the added benefit of being able to keep the lights on during these impending power cuts.

Chapter 8 - Maintenance

    MAINTENANCE WILL ALWAYS be ongoing & will need to be carefully programmed into your diary. It is not something that should be skimped on, or omitted from your schedule. It will need to be taken seriously & it will be advisable to keep an ongoing record of each of the elements & if possible also to keep photographs so as to compare the condition of the system elements with how they were perhaps a year ago. No matter how good you think your memory is, it will not be good enough to remember the exact condition of something the previous year. It may also be helpful to communicate any problems you find via email to the manufacturer or installer so you can attach photographs of a component that is degrading year on year.

  Each element of the installation will need to be examined in turn & it may be helpful to develop & set a routine. Also it is best to keep a close eye on the systems so that you are familiar with how they perform during various weather conditions. Then, you will be instantly alerted to any problems if they occur. Providing you rectify a problem in good time, your energy harvest should only have a minimal period of down-time.

  PV maintenance

  PV PANELS ARE GENERALLY robust, therefore there is only a small chance that they could fail. They are therefore deemed to require little

maintenance. However, failures are not unheard of & of those failures, they generally tend to be equipment related & not with any of the components. Luckily, even though the panels are robust, they are still getting stronger & have a better build quality.

  PV panels should have a warranty for 25 or 20 years, therefore if a panel does fail, you should obtain a replacement from either the manufacturer or the retailer. However, there may be certain requirements that you will need to undertake for the warranty to be effective & therefore keeping a detailed diary (with photographs) will help prove you have inspected the installation & also the condition of the elements.

  You should also adhere to any/all of the recommendations in the warranty paperwork to ensure you are fully protected. If you have an installer to fit the system, then they should leave you with a maintenance checklist to follow. If you do end up having to pay for a replacement panel, expect to pay approximately £800.

  At the very least, the first step should be to clean the panels to ensure that they obtain the maximum possible amount of energy from the sun. Your particular location should determine the frequency that you undertake this task. If for instance you are located near the coast, guano may be a frequently occurring problem & therefore you may need to undertake this task at a high frequency. If blown leaves are a problem, then again they will need to be cleared of the leaves & cleaned when the build up of leaves becomes a problem. Luckily, leaves should only be a problem in the autumn. Rain does tend to clean the panels to some degree, but grime & dust will build up on the panels & this will need to be cleaned off. It will then be possible to check the glass for discolouration & any internal delamination. Cleaning the panels will be no different to cleaning

windows, although if they are positioned on a rooftop, then this may pose some difficulties if you do not have access equipment, therefore it may be prudent to obtain a tower as you could require it a few times a year.

  The frames should also be examined for damage & stress, as well as the cabling that exit the panel & any joints &/or connectors at this location. All clamps, screws & bolts should be visually inspected too. Whichever mounting system you have utilised should also be examined. This includes the framework, fixing points & clamps. If the panels are mounted at ground level, then any surrounding vegetation should be removed or cut back & the concrete bases examined for any damage & cracking.

  There is a City & Guilds qualification available for maintaining small scale solar panels (2399-14) that is set over three days, but the entry requirements for this course is another City & Guilds qualification, therefore it is unlikely this course or similar courses will offer good value for money.

Chapter 9 - Using a calculator to do the maths

    BEFORE YOU CAN UNDERTAKE the calculations in this book, it is important to realise that you would have previously worked similar calculations when you were still at school, therefore it is not anything you have not undertaken previously. Also, now you can use a calculator, will not be marked by a teacher & will use the mathematics to save yourself money. With a little practice, the mathematics will become simple & what could be better than saving yourself money.

  All you need to remember is that the letters in the equations are just substituting numbers. They are shown as letters as they are variable. For instance, 30 watts, 3kW, 5kW are all power levels & any could be used in an equation relating to electrical power, therefore a substitute letter is used & you just have to replace that letter for the number. Also, the equations are written back to front, the answer is on the left, the sum is on the right. Therefore you can swap the order if you find it helpful.

  Finally, when you have swapped the letters for numbers, calculate from right to left, top, then bottom, working the figures in the brackets first.

  In this example from earlier in the book, it is used to find the voltage.

    IF YOU CAN REMEMBER back to chapter 3,

    SO TO DO THE MATHEMATICS in this example, just multiply I by R, this will give V (the voltage). If I is 20 & R is 12, the sum will be:

    THE ANSWER IS OBVIOUSLY 240 volts. As you can see, there was nothing complicated there & you were most likely able to complete that calculation in your head.

  The principles are exactly the same for the more complex equations. Just follow the rules, right to left, top then bottom & substitute the letters for numbers before you start. You may need to use a scientific calculator to do some of these, but again it’s just a case of pressing the corresponding buttons. If you do not have a scientific calculator, then you will definitely have one on your computer or even on your mobile phone (if you have a smart phone).

  Another example is to calculate the voltage drop for a single phase AC (or DC) circuit.

    VD = Voltage Drop in Volts.

 

I = Cable Current in Amperes.

  R = Cable Resistance in Ohms (Ω) (Ω/km).

  L = Cable length in meters.

  If I is 20 & the length of the cable is 5 meters, then L is 5 (because it is 5 meters). You can obtain the resistance for the cable from charts or from the cable manufacturer. In this instance it is assumed that it has a value of 0.0002, therefore the equation will be as follows:

    IT IS THEREFORE A MUCH simpler matter to calculate the answer. Always start with the brackets.

    THEN DIVIDE THE TOP from the bottom.

    FINALLY MULTIPLY THE two figures to find the voltage drop

  The answer is as follows:

 

  THEREFORE THE VOLTAGE drop will be 0.00004 volts.

  Again I’m sure you will agree that was not too difficult, therefore to complete each & every one of the calculations just follow the same rules:

  Start with the brackets, work from right to left & top to bottom & substitute the letters for numbers before you start. You will then be able to undertake the calculations with ease & with accuracy if you follow those simple rules.

  If you still find these equations a little daunting, then there are calculators freely available on the internet that will calculate the mathematics for you. You can even download suitable calculators onto your tablet or smart phone that will also do the mathematics. There are therefore multiple options available for your calculations.

Chapter 10 - Easing the installation

    IF YOU WISH TO MAKE your life as easy as possible, the first step is to use the correct tool for the job at hand. For instance you can not saw a length of wood with a bread knife, knock in nails with a toffee hammer or secure nuts & bolts with tweezers. Therefore at the very least you will require a basic tool kit.

  More specialist tools that will be useful would include the following items:

  If working off a ladder is problem, one solution may be to use a scaffold tower to help make working at height both easier & safer. There are many heights & widths available & they can be purchased from £600 from a well known auction site in either steel or aluminium. If they are to be used regularly, it may also be advantageous to install wall mounted anchor loops so that it can be securely tied to a wall when it is used against a wall to give access to the roof for checking &/or maintaining any roof mounted PV panels &/or solar hot water panels. If a tower is obtained that is square, it would be suitable to be constructed around a wind turbine’s tower, therefore making maintenance far easier than working from a ladder.

 

  FIGURE 51 AN INEXPENSIVE scaffold tower (Public Domain Image © 2017)

  The next piece of equipment to consider is a kill-a-watt This simply informs you as to how much power an appliance is using. It just plugs into a wall socket & the appliance plugs directly into it. It simply acts as a flow-through meter, measuring the flow of electricity. It is possible to use only one of these meters as they just plug in when you need them. It will therefore be possible to measure how much electricity any electrical appliance is using & therefore help make informed decisions regarding power usage. You can also then make direct power comparisons when you need to replace an item for a more energy efficient model. These meters are very inexpensive & can be obtained online from £10 each.

 

  FIGURE 52 KILL-A-WATT meter (Public Domain Image © 2017)

  If you are able to install or adjust the solar array, then to ensure that you have set them to the correct angle, you will need to use an angle A spirit level will generally only measure on the horizontal or vertical planes, but by using an angle gauge you can easily find any angle. Inexpensive models can be obtained online for approximately £20.

 

  FIGURE 53 AN INEXPENSIVE angle gauge (Public Domain Image © 2017)

  A multimeter can measure many things, voltage, current & resistance, therefore it is an invaluable tool to use when installing, checking &

maintaining an electrical system. A generic model can be obtained online for as little as £10. They are generally sold complete with probes.

 

  FIGURE 54 AN INEXPENSIVE multimeter (Public Domain Image © 2017)

  A similar tool is known as a clamp meter or a current clamp. It is similar to a multimeter, but is far safer to use as it measures the magnetic field & therefore does not have to make physical contact with the bare metal. Figure 55 shows an inexpensive clamp meter which can be bought online for £25.

 

  FIGURE 55 AN INEXPENSIVE clamp meter (Public Domain Image © 2017)

  Both the multimeter & the clamp meter are similar instruments as they both do the same thing, but neither will measure the surge when an electric motor starts. To do this, an expensive multimeter or an expensive clamp meter will need to be purchased, one which can measure a surge. The cheapest available online in the UK can be purchased for approximately £70.

  Also, there is a megohmmeter to consider. This is a type of ohmmeter that is used to measure the electrical resistance of insulators. Insulating components, for example cable jackets, must be tested for their insulation strength at the time of commissioning & as part of maintenance of high voltage electrical equipment & installations. For this purpose megohmmeters which can provide high DC voltages (typically in ranges from 500v to 5kV) at specified current capacity are used. This instrument can therefore check your cable runs for ground faults. A typical cheap generic model can be purchased online in the UK for £30.

 

  FIGURE 56 AN INEXPENSIVE megohmmeter (Public Domain Image © 2017)

  A final tool that can assist measure the path of the sun at your site, which will take into consideration your site’s shading & when added to weather data, it will produce an accurate site specific solar analysis. It is called a solar pathfinder & has several components, the first is a clear plastic dome that sits on top of a small tripod & this measures & traces the solar irradiance throughout the day. Figure 57 shows a plan view of the dome.

 

  FIGURE 57 A PLAN VIEW of the Solar Pathfinder (Solar Pathfinder © 2017)

 

  FIGURE 58 A TRACE MADE by the Solar Pathfinder (Solar Pathfinder © 2017)

  Figure 58 shows what a daily trace looks like. From this, it can therefore calculate what hours of the day throughout the year the site will be shaded, the percentage of solar irradiation that the site receives on every day of the year & the altitude & azimuth of all objects on the horizon. This would be a wonderful piece of equipment if it were not so expensive. The current price for the hardware alone (without the software that will simplify the output) is $300 USD. If you wish to use the software, then it will cost an additional $189 USD.

 

  FIGURE 59 SOLAR PATHFINDER angle report (Solar Pathfinder © 2017)

 

  FIGURE 60 SOLAR PATHFINDER site report (Solar Pathfinder © 2017)

  These are not the only tools that are available which will be beneficial. The main piece of equipment that you can use is the internet as there are numerous places on the internet that you can get help & advice. There are numerous chat rooms & forums available where there are lots of helpful people who are more than willing to give advice & pass on the benefit of their wisdom. You only need to ask for help & advice & people from all over the globe will be able to assist you with your own DIY home energy solution. That type of help is priceless.

Chapter 11 – Obtaining finance, grants & mortgages

    Hidden benefits from using a CPS installer

  IF YOU OPT TO USE ONE of the approved contractors from the Microgeneration Certificate Scheme (MCS) to fit your PV system &/or wind turbine system, then there is a financial benefit as a consequence.

  This is the Feed-in Tariffs scheme (FITs) which was designed by the UK Government to be an incentive to the uptake of electricity generating renewable technologies such as solar panels & wind turbines. This means that if you have an eligible installation you could be paid for the electricity you generate as well as for the surplus electricity you export to the grid.

  Since 1st April 2010, for installations up to 50kW will need to use an MCS certified installer & an approved technology (which includes solar & wind turbine power installations) to be eligible for FITs. The MCS installer will provide an MCS Certificate once the installation is complete. To register for the FITs you will then need to send the MCS Certificate to your FIT Licensee (an electricity company) who will complete the registration process. You will then benefit from receiving FITs payments made up of two components (although this is subject to change):

  The generation tariff: your chosen energy supplier will pay you a set rate for each unit (or kWh) of electricity you generate. Once your system has

been registered, the tariff levels are guaranteed for the period of the tariff (up to 20 years) & are index-linked. The export tariff: our chosen energy supplier will pay you a further rate for each unit you export back to the electricity grid, so you can sell any electricity you generate but do not use yourself. At some stage smart meters will be installed to measure what you export, but until then it is estimated as being 50% of the electricity you generate.

  The amount that individuals are paid tends to fluctuate due to whatever government is in power & how keen they are on being seen to be green. Currently (at the time of writing), the upper limits of the tariffs are as follows on the following page:

 

  IT IS ALSO IMPORTANT to realise this is the top tier. There is also a medium rate & a lower rate. Which rate you receive will depend on when the installation was commissioned &/or registered. Whichever tariff is applicable to your individual installation, expect it to change due to the

political climate & governmental budget considerations. Currently if the installation has not been installed by a MCS approved contractor or is greater than 50kW, then you can apply through the Roo-FIT scheme via OFGEM. Any electricity you export will be to whichever company operates in your area, as shown in figure 61.

 

  FIGURE 61 UK DISTRIBUTION network companies (Inexus © 2016)

  Renewable Heat Incentive (RHI)

 

THE DOMESTIC RENEWABLE Heat Incentive (RHI) for the residential market was launched in 2014, which made a payment (provided you purchase a system they recommend & also use one of their installers) as indicated on the following chart:

 

 

Currently, the RHI will work in a very similar way to Feed-In tariffs. Homeowners will be paid a fee for generating their own hot water using eligible technologies which includes solar thermal water heating panels & collectors. The amount of hot water generated will either be measured or estimated & then you should receive a payment for the total amount created.

  Since its inception, the UK government has revised the scheme a number of times. The latest revision was on September 2017 & the guidelines for the current revisions, along with the eligibility requirements & a calculator are available on the Also, currently, the feed in tariffs are tax free for domestic installations, but commercial installations are not. This may well change in the future.

  Currently, there are different types of payments that make up the FIT scheme.

  The generation tariff (element) rewards you for actually generating electricity. This is estimated from whatever size your system is. For instance, a 4kW system would pay one rate; a 10kW system would pay another rate. The export tariff (element) rewards you for what you actually export from your system into the National Grid system. This element is measured. Together, the generation tariff & the export tariff are added together & these are what make up the FIT’s payments.

 

There is also often what is called an ‘energy offset’ if you look at what the MCS installers quote, but this is just what you could save from your energy bills. Therefore it is best ignored because it is just a way of double counting to make their systems look better than what they are.

  Further grants

  CURRENTLY, THE UK GOVERNMENT are working towards the EEC’s Renewable Energy Directive. This EEC directive sets out a requirement that all EEC members must source 20% of their energy from renewable energy sources by 2020. As the UK is set to withdraw from the EEC, it is impossible to predict exactly how this will affect government grants in the future, but currently, there are sources of income to be made from creating energy from what the government term as renewable energy sources.

  Also, as governmental grants & incentives are liable to change, amendment &/or cancelation at any time & sometimes with little or no notice as they move money from one area to another in an attempt to appease various bodies & organisations, it is important to first check on the validity of any information before committing to the expense of any installation.

  Grants for PV’s

 

IN THE UK, THERE ARE currently no national grants available for installing PV on domestic or commercial properties. What the government does provide is known as FIT’s payments. That is the Feed In Tariff, or to put it simply, payments that are issued for the energy that ‘you’ produce, either at a domestic premises or at a commercial premises. The government has historically cut & raised these payments, so the FIT

payments are set for a fixed period of 20 years. This starts from when you first register, but there are strict ‘rules’ that must be met to qualify for these payments.

  See the section entitled ‘Hidden benefits from using a CPS installer’ for further information on FIT’s.

  One positive note for FIT’s is that they are (currently) tax free payments for the duration of time that they are paid. This is currently set at 20 years.

  There are however companies that will install & maintain a free PV installation on domestic or commercial properties in the UK. It is those companies that collect the FIT’s payments & make a small annual payment to the property owner. Essentially they ‘rent your roof slope’. This may seem to be a financially sound proposition to anyone who wishes to install a PV installation but can not afford the capital outlay, but as these schemes create what can be best described as a ‘flying freehold’ over your property. It should also be noted that it will be impossible to maintain your roof slope under the installation; there are exorbitant fees if you wish to have the installation removed before the end of the long contract period & due to these factors it makes the property virtually unmortgageable. They are therefore not an attractive option.

  Grants for BIPV’s

 

IN THE UK, THERE ARE currently no national or local grants available specifically for installing BIPV’s on domestic or commercial properties. What the government does provide is known as FIT’s payments as detailed in ‘Grants for PV’s’ on the previous page.

 

Mortgages

  YOU MAY ALREADY KNOW that the word mortgage is a corruption of two French words & translates into English as ‘death-grip’, but how will an installation of any of the energy saving measures found in this book effect an existing mortgage on property, a remortgage or even a new mortgage for someone wishing to purchase a property that has been outfitted with of any of the energy saving enhancements? This section will therefore address some important questions.

  How mortgages can be affected by PV panels

 

THERE IS ONE IMPORTANT question with regard to mortgages & a PV installation. Is the installation owned by the property owner, or is it a ‘rent a roof’ installation.

  If the answer is that it is a ‘rent a roof’ installation, then obtaining a remortgage may prove difficult & obtaining a new mortgage may prove impossible for some.

  The trouble stems from the fact that it is an encumbrance on the property. Most of these ‘rent a roof’ installations were installed with a 20 or 25 year lease that is attached to the ‘property’, not to the individual who owns the property. This means that the lease essentially becomes part of the property. If subsequently the property were to be resold, then the new ‘buyer’ would be buying the lease along with the property. If that new buyer was to then fall behind on their repayments, the ‘mortgage lender’ may then wish to repossess the property & if they do, the ‘leaseholder’ who owns the PV installation will only remove the PV installation if the

‘mortgage lender’ can demonstrate in court that they failed to sell the property because of the PV installation. This is a complicated legal scenario & therefore at present, it explains why mortgage lenders will refuse any remortgages & new mortgages on any properties that have a ‘rent a roof’ PV installation, regardless of whether they had a mortgage when the ‘rent a roof’ lease was initiated or not. Therefore anyone who has a ‘rent a roof’ PV installation on a property in the UK could have an unmortgageable property.

  This scenario may change over the coming years as things are worked out in the court, but at present, it would be advisable to avoid any properties that have a non-compliant ‘rent a roof’ PV installation & if you have one on your property, remove it, or ensure you have conformity before you try to sell the property.

  The Council for Mortgage Lenders claim that they support all renewable energy initiatives in principle, & blame the current ’rent a roof’ situation on the fact that a proportion of the panels used on ‘rent a roof’ schemes have not been fitted to their, nor individual mortgage lenders ‘minimum standards’. This may be true in part, as when the ‘rent a roof’ scheme started there were a large number of new companies wishing to jump on the FIT’s gravy-train & there are therefore a number of installations that will be below the standard that would be expected.

  Of the domestic properties in the UK, an estimated 2% have a PV installation. That equates to approximately 500,000 properties. Therefore there will be a certain proportion of those 500,000 properties that will not meet the minimum standards required by either the Council for Mortgage Lenders or many of the individual mortgage lenders.

 

Of the properties that are in the ‘rent a roof’ scheme. Any that had a mortgage at the time of installation, would have needed to obtain permission (consent) from their mortgage lender. It is reasonable to assume that there are some properties in the ‘rent a roof’ scheme that have not obtained, or did not apply for consent. Also, there will also be some that did obtain permission, but the materials used, or the methods used fail to meet the minimum standards that were required. However, the majority of the installations should have all the requisite permissions in place & are built to the required standards. Reputable firms would & should be aware of the expectations of mortgage lenders & install their installations ensuring that they are in compliance.

  It would therefore be prudent for any potential purchaser to check on the legality & quality of the installation. This would be good advice to any property purchase whether it is a cash purchase or bought with a mortgage. The first check would be to ensure whether there is MCS documentation. If not, proceed with caution. If there is no documentation, it will at least provide an opportunity to reduce the asking price, providing that you are prepared to obtain documentation yourself for the installation if you proceed with the purchase, but if it will be subject to you obtaining a mortgage, you will never get a mortgage on that property due to the lack of documentation & possible conformity. If however the installation is owned outright, then it should be seen as an asset, as it will provide a modest tax free income for the owner over several years.

  It is also advisable to check on the legality of the installation with regard to the Local Authority. If the homeowner can not provide documentation to prove the installation fell within the scope of ‘permitted development’ when it was first installed, then expect to see documentation either granting Planning Permission or acknowledging it is permitted

development. Similarly, expect to see documentation demonstrating compliance with the Building Regulations. If a property owner can not produce any documentation regarding the legality of their installation, it would be best to find another property as the problem of obtaining retrospective Planning Permission &/or retrospective Building Regulation approval is fraught with problems that are best avoided.

  Whether a PV installation actually adds a premium to a property price is debateable, but on gocompare.com, 14% of potential buyers added solar panels as a requirement in their wish list, but the estate agents Savills advise ‘to place a PV installation at the rear, so as not to affect the original appearance of the property’.

  Also, if you are planning to install a PV installation at a property, whether it is a mortgaged property or not, & whether it is a ‘rent a roof’ scheme or not, it will be in your best interests to ensure that the installation is in complete compliance with all Local Authority Planning conditions & keep all documentation, obtain documentation to prove it falls under Permitted Development (if it is applicable). Ensure it is built with the Local Authority Building Regulations Approval & keep all documentation to prove it. Ensure it is constructed to all relevant & current standards & that you obtain a MCS Certificate so as to avoid any potential future problems when you sell the property. As these are the requirements that a bank or building society would wish to see & study when assessing a property for the suitability for a mortgage, therefore attempting to buy a property, using a mortgage without this paper trail will at best be problematic, or most usually just rejected. Also, if the property is leasehold, you may also need the permission of the freeholder.

  The same points will be true for properties benefiting from BIPV’s.

Table of illustrations

    THE COVER ILLUSTRATION is copyright to Phoenix Xavier (2018).

  Figure 1 Simplistic view of the components (P Xavier © 2017)

  Figure 2 Ohm's law triangle (P Xavier © 2017)

  Figure 3 Ohm's law 2nd triangle (P Xavier © 2017)

  Figure 4 Global annual sun (SolarGIS © 2013 GeoModel Solar)

  Figure 5 Photovoltaic cell (Public Domain Image © 2005)

  Figure 6 Cutaway of a typical PV module (P Xavier © 2017)

  Figure 7 PV cell, PV module, PV array (P Xavier © 2017)

  Figure 8 Polycrystalline & monocrystalline (Public Domain Image © 2014)

  Figure 9 PV I-V curve graph (P Xavier © 2017)

 

Figure 10 Average European solar irradiance (European Union Joint Research Centre © 2011)

  Figure 11 Weather effected I-V curve (P Xavier © 2017)

  Figure 12 Path of sun throughout the year (P Xavier © 2017)

  Figure 13 Magnetic poles in 2005 (Public Domain Image © 2015)

  Figure 14 Adjustable compass (Public Domain Image © 2005)

  Figure 15 Annual PV angles (P Xavier © 2017)

  Figure 16 Effects of panel shading (P Xavier © 2017)

  Figure 17 Inter row spacing (P Xavier © 2017)

  Figure 18 Temperature voltage ratio (P Xavier © 2017)

  Figure 19 Series connection (P Xavier © 2017)

  Figure 20 Parallel connection (P Xavier © 2017)

  Figure 21 PV performance on a sunny day (P Xavier © 2017)

  Figure 22 PV performance over a cloudy morning (P Xavier © 2017)

 

Figure 23 PV module rating sticker (Public Domain Image © 2015)

  Figure 24 U bracket (Public Domain Image © 2017)

  Figure 25 U bracket fixed in place (Public Domain Image © 2017)

  Figure 26 Tiled over bracket with rails fitted (Public Domain Image © 2017)

  Figure 27 Dektite flashing (DEKS Industries © 2017)

  Figure 28 Fixings with integrated flashings (Ibacos © 2017)

  Figure 29 HDPE panels ready to accept PV panels (Severn Valley Renewables © 2017)

  Figure 30 HDPE panels ready to accept PV panels (Severn Valley Renewables © 2017)

  Figure 31 The finished in-roof system (Severn Valley Renewables © 2017)

  Figure 32 Close up of the edge detail for the in-roof system (Severn Valley Renewables © 2017)

  Figure 33 Plastic tub (Public Domain Image © 2017)

  Figure 34 Plastic tubs on a commercial property (Public Domain Image © 2017)

  Figure 35 Preformed steel frame on a commercial property (Public Domain Image © 2017)

  Figure 36 Adjustable steel frame (Public Domain Image © 2017)

  Figure 37 East/West mounting (Public Domain Image © 2017)

  Figure 38 DIY metal frame structure (Public Domain Image © 2017)

  Figure 39 DIY wooden frame structure (Public Domain Image © 2017)

  Figure 40 Pole mount (Public Domain Image © 2017)

  Figure 41 Axis tracking on pole mount (Public Domain Image © 2017)

  Figure 42 HSAT array, Vellakoil, India (Vinay Kumar © 2014)

  Figure 43 TSAT array, Siziwanggi, China (Vinay Kumar © 2013)

  Figure 44 TTDAT array, Siziwanggi, China (Vinay Kumar © 2013)

  Figure 45 AADAT array in Toledo, Spain (Public Domain Image ©

  Figure 46 Inexpensive Chinese generator (Public Domain Image © 2017)

  Figure 47 Tesla solar tiles (Tesla solar roof tiles © 2017)

  Figure 48 PV glass (Public Domain Image © 2017)

  Figure 49 Solar parking canopy at University of Madrid (UAM), Spain (Hanjin © 2013)

  Figure 50 PV Façade at the Social Services Centre Jose Villarreal, Madrid, Spain (Hanjin © 2013)

  Figure 51 An inexpensive scaffold tower (Public Domain Image ©

  Figure 52 Kill-a-Watt meter (Public Domain Image © 2017)

  Figure 53 An inexpensive angle gauge (Public Domain Image © 2017)

  Figure 54 An inexpensive multimeter (Public Domain Image © 2017)

  Figure 55 An inexpensive clamp meter (Public Domain Image © 2017)

  Figure 56 An inexpensive megohmmeter (Public Domain Image ©

  Figure 57 A plan view of the Solar Pathfinder (Solar Pathfinder © 2017)

  Figure 58 A trace made by the Solar Pathfinder (Solar Pathfinder © 2017)

  Figure 59 Solar Pathfinder angle report (Solar Pathfinder © 2017)

 

Figure 60 Solar Pathfinder site report (Solar Pathfinder © 2017)

  Figure 61 UK distribution network companies (Inexus © 2016)

About The Author

   

  MR XAVIER IS IN HIS 40’s & currently living in the South of England. He is desperately trying to make a living, live a good life, learn to play the ukulele, grow a rather splendid handlebar moustache & decide what to have for dinner tonight. With his other hand he’s trying desperately to learn another language whilst also planning the next chapter of his life.

  This & all his other books are available online from reputable ebook retailers.

 

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[2] https://www.eia.gov/todayinenergy/detail.php?id=26212 – 28/08/2017

 

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[22]

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