TO COMPARE AND TO CONTRAST THE FEASIBILITY OF PAINTABLE PHOTOVOLTAIC (PV) WITH EXISTING SILICON BASED TECHNOLOGY

ABSTRACT

The main ideal of this title that has been given to me is about the comparison between paintable photovoltaic silicon solar cells to the existing integrated photovoltaic solar cell on buildings. It highlights the basic functions and the operation of a typical photovoltaic silicon cell that can be found in an integrated photovoltaic solar panels. Besides that, the main achievement and purpose for me is to conduct a research about the principle of photovoltaic cells, the benefits and downsides of photovoltaic panels, weather forecast of different part of the countries around the world as well as the calculation costs of the products.

Is it suitable for every country to adopt and utilize the benefits of renewable energy such as photovoltaic cell today and how effective it is for a paintable photovoltaic cell in comparison to integrated photovoltaic solar cells?

TABLE OF CONTENTS

DECLARATION STATEMENT

ABSTRACT

ACKNOWLEDGEMENTS

TABLE OF CONTENTS

LIST OF FIGURES

GLOSSARY

1. INTRODUCTION

1.1 Aims

1.2 Objectives

1.3 Work Stages

1.3.1 How to start off with Work Stages

1.3.2 Photovoltaic Field

1.3.3 Domestic Photovoltaic cells

2 LITERATURE REVIEW

2.1 What is Photovoltaic Cell?

2.1.1 How silicon makes a solar cell?

2.1.2 Anatomy of a solar cell

2.1.3 Energy loss in a solar cell

2.2 Types of Photovoltaic Solar Cells

2.2.1 The differences between Monocrystalline and Polycrystalline

2.3 How much electricity is produced by Photovoltaic cells?

2.3.1 Case study

2.3.2 How much does a solar panel cost?

2.3.3 Off-grid Setup

2.3.4 Electric usage history

2.3.5 Photovoltaic solar cells and new technology

2.4 Feed-in Tariff in the United Kingdom to support the United Kingdom photovoltaic market.

2.4.1 Off-Grid Solar Cell Setup

2.4.2 Photovoltaic controller setup

2.4.3 Feedstock

3 WHY STUDY MATERIALS SCIENCE AND ENGINEERING?

3.1.1 Classification of materials

3.1.2 Research on an introduction of materials science and engineering

3.1.3 Why Solar Energy?

3.1.4 Advantages and disadvantages of Solar Energy

3.1.5 Photovoltaic Power Plant in the United Kingdom

4 WEATHER CLIMATE FORECASTS

4.1 Temperature climate

4.2 Warmest and coldest months

4.3 Length of daylight

4.4 What is the weather like around Britain?

4.5 Summary of temperature and rainfall around Britain.

5 CONCLUSION

5.1 Further development

5.2 Future remarks

REFERENCES

LIST OF FIGURES

Figure 1 – shows the basic function of a solar cell. [1]

Figure 2 – shows the N-type and P-type found in the silicon based PV cell. [2]

Figure 3 – shows the layers of a silicon based photovoltaic cells. [21]

Figure 4 – shows the efficiency of crystalline and thin-film cells. [28]

Figure 5 – shows the different types of photovoltaic cell materials. [27]

Figure 6 – shows the comparison between the monocrystalline and polycrystalline cells. [28]

Figure 7 shows how a solar cell is assembled into a solar module and into a PV system. [25]

Figure 8 – price of silicon PV cells in Watts. Note that the currency is in Dollars. [23]

Figure 9 – shows the mean temperature of thermal effects in the United Kingdom. [24]

Figure 10 – examples of renewable energy that can be implemented with PV cell. [29]

 

GLOSSARY

• Positive poles: (+)

• Negative poles: (-)

• Gallium Arsenide: Ga AS

• Power: Watts

• Voltage: V

• Current: Ampere

• Electron volts: eV

• Silicon: Si

• Cadmium Telluride: CdTe

• Copper Indium Diselenide: CIS

• Kilowatts: kW

• Kilowatts per hour: kWh

• Milliwatts: mW

• Photovoltaic: PV

• Multi-junction: also called as Cascade or Tandem

1.   INTRODUCTION

Innovative technologies has been steadily increasing each year without a doubt, and in fact it is a very good practise for the younger generations to be inspired by this new innovations and ideas because in the future renewable energy will play an important role to every countries in the world as a substitution for coal gas and fossil fuels.

Renewable energy sources are essential and plays an important role in our lives. There are many unpredictable cases of unexpected climate change that is happening to our world that sometimes even scientist couldn’t able to obtain enough research data of how Mother Nature is behaving. In such cases like global warming, change in climate temperature, oceans becoming much warmer in recent years which are affecting sea lives marines as well as forest are caught in fire because of land temperature which could go up to more than 50°C.

It is sad to say that all of this possible causes are being pointed out to the 7 billion of people that are currently living in this world today. Most of it are coming from the responsibilities of those people who has taken for granted knowingly it could greatly affect our earth in a short period of time. Most people had already taken steps and precautions on how to persevere our earth by looking into alternative ways on how to reduce the constant usage of fossil fuel and so on. It is the reality we are living in right now, and therefore human beings are constantly evolving and learning new ways to come up with new innovation and new research to make the world a better place.

As mention in the first paragraph, renewable energy plays a vital role in our lives and the new generation has already come up with new researches and innovations on how to take full advantage of Mother Nature. It may not seem like it could greatly reduce the effect on global warming right now, but in terms of long run it could greatly have an affect the way we live and also taking preliminary actions which we could prevent the same disasters from occurring again in the near future. Not only are we doing this to make the world an eco-friendly place to live in, but also for our next generation to come so that they would not have to face the same problem that we are facing right now.

Needless to say, renewable energy like the energy from the wind which can generate electricity and power households from wind turbines with sufficient enough of wind speed it is free and eco-friendly. Another great example of how to reduce the usage of fossil fuels for the basic need in our lives is the renewable energy from our sun. Nowadays many scientist and engineers are constantly looking for many ways on how to improve as well as persevere the nature of our earth by adopting free renewable energy that was already right in front of us, the sun. In this research, I will be conducting different types of analysis and experiments on paintable Photovoltaic Cell to the Photovoltaic solar cells that are integrated on buildings and house rooftops whether are there differences or similarities in terms of the generate power input, the conversion of heat to electrical energy, the costs of manufacturing, the benefits and downsides of paintable Photovoltaic cells as well for integrated Photovoltaic solar cells.

1.1      Aims

The aim for this project is to identify and to do a comparison between paintable photovoltaic and an existing integrated photovoltaic silicon based solar panels. Therefore, in order to achieve this, I need to:

1. Do an analyzation the advantages and disadvantages of paintable photovoltaic that is applicable to building structures, vehicles and electronic gadgets and the costs for manufacture. To also compare and contrast between photovoltaic solar cells in paint to the conventional silicon based paint in the industry.

2. Do a research on the productivity in photovoltaic solar cells on journals, online media, books and magazines. Research on the market table of photovoltaic solar cells if it would be applicable soon.

3. Do research if there are any effects on photovoltaic solar cells on the design of the building, the height, the geography landscape of where it is being installed. Will it be an effective product that could be able to provide better and cleaner environmental green to the world?

1.2      Objectives

The main objectives for me to conduct this feasibility research is to gain some analysis data and relevant outcomes of the beneficial upsides and downsides of paintable photovoltaic as well as the integrated solar panel on houses. Here, there are five objectives that I have obtained and need to be carry out:

1. To identify and construct an appropriate costing of manufacturing a photovoltaic solar cell.
2. To find out which material is more sustainable and better electric conductor for the paintable photovoltaic solar cells.
3. To conduct a research on the general photovoltaic solar cells and the basic function.
4. To do a research on the weather forecasts in the United Kingdom and on other parts of the countries.

 

1.3      Work Stages

1. Conduct research on general photovoltaic solar cells.

• Research on the history of how about photovoltaic solar cells came about.
• Read on the explanation of photovoltaic solar cell by borrowing books from the library.
• Find out about the foundation of semi-conductor electricity in photovoltaic solar cells.
• Purchased a cheap mini-photovoltaic device online and do an analysis on it.

2. Identifying and construct appropriate costing.

• Find out the appropriate costing.
• How much does one mini-cheap budget photovoltaic cost?
• The price to buy or purchased a single photovoltaic solar cells. For example: the cut-down costs, applicable materials, the manufacturing default in paints, and etc.
• Research on the actual manufacturing cost for a photovoltaic solar cells.
• Do a calculation on the prototype and those that are in the industry currently.

3. Investigate applicable material as substitutional photovoltaic solar cells to default silicon bases.

• Find online about the default silicon bases found in paint by doing research.
• Possibly if able to purchase an actual photovoltaic paintable solar cells online (if none), then work on the purchased cheap mini-photovoltaic device.
• Once done analysing and experimenting the cheap purchased mini-photovoltaic device, do a comparison or a general calculations between the default silicon based technology and the device.
• Find out a suitable and sustainable way by implementing and substituting it into the paint without the use of silicon based.

4. Find out which material is more sustainable and have a better electric conductor for the paintable photovoltaic solar cells.

• Gather information and different types of materials.
• Do a lab analysis and experiment on the different type of materials with the paintable photovoltaic solar cells on it.
• Collect data and calculation of the end results.
• By comparing all of the materials used for the paintable photovoltaic solar cells, find out which is much more sustainable for the paint to be used on.
• Do an another experiment of the different type of materials together with the paintable photovoltaic solar cells on it to find out which material is a good electric conductor.
• Compare and contrast between the different types of materials with a chart of the chart of the sustainability/durability paintable photovoltaic solar cells lifetime to how much percentages of the electric in a conductor quality it can produced.

1.3.1     How to start off with Work Stages

There are many journals and online articles regarding to the general information about photovoltaic solar cells. Here, I have a lists of where I have tried to do based on the research and the possibility of gathering information from different resources:

1. Books
2. Journals
3. Social media
4. Online articles
5. Search books related to photovoltaic solar cells in the library
6. Newspaper
7. Magazines
8. Friends
9. Anyone related to this field

1.3.2     Photovoltaic Field

A typical photovoltaic solar cell grid can be built into a wall, the roof of a newly constructed building or into existing buildings. There are some owners that uses photovoltaic solar cell grid in the outskirts of the city centre. In a recent research, the advances in the manufacturing process and in technology continues to reduce the cost of solar cells. Solar cells are the fastest growing renewable energy technology in the world. An improved photovoltaic grid can coordinate and stay aligned with the sun’s path through the sky.

The main improvement for this photovoltaic grid involves in creating more electricity for any photovoltaic systems that cannot track the sun. The power stations are efficient and cost effectiveness and they don’t produce harmful emissions or fuel costs.

1.3.3     Domestic Photovoltaic cells

Not many people are fully aware of the United Kingdom’s photovoltaic market to date’s. However, the United Kingdom’s climate Change Bill has promised that there will be an effective and immediate action to cut down the carbon dioxide emissions to at least 60% by 2050. By this, it makes Britain one of the top flight global leaders against climate change. Such targets like these are paving the way for the younger generation with the help of domestic photovoltaic systems, or solar energy that can be generated by the usage from the ultraviolet ray lights coming from the sun.

2         LITERATURE REVIEW

Photovoltaic (PV) system are a modular structure. Means to say that Photovoltaic cells that you find on those integrated house rooftops are mostly made up of many subdivide systems that are being broken down into many individual small parts of semiconductor silicon based are made up together of what you called a solar cells. All of this which are being linked together plays an important role on generating electricity, by the amount of heat the Photovoltaic cells are able to absorb from the sun. The solar cells of a Photovoltaic system can be connected either in series or parallel in contrast to its number of Photovoltaic cells use and its combination. (Inhabitant.com, 2017)[4]

Photovoltaic system can be made in various ways and sizes. The power that it produced from the sun’s heat energy to electrical energy is perpendicularly parallel, ranging from mill-watt system in watches or calculators to megawatt systems for central power production. For integrated Photovoltaic solar cells that can be found on buildings, normally the average power supply systems are usually in the range of several kilowatts of nominal power. In addition to that, for every building-integrated system there are a basic element of a generator in a Photovoltaic module which plays an important role. The number of modules in series will determine the system voltage and the current of the plant which can be sized by parallel connection of the module strings.

For desired output, power is the product system voltage and current. Building-integrated Photovoltaic systems have an economic advantages over conventional Photovoltaic generator systems. All of this area are part of the building envelope, ideally replacing conventional façade or roof materials. (Inhabitant.com, 2017)[4]

What is a Photovoltaic cell made off? Well, Photovoltaic cell is a chemical composition that takes the energy from the reflected light and turns that into an electrical energy. Photovoltaic cells have a semi-conducted feature, create voltage and current by providing electron movement between (+) and (-) poles. Photovoltaic cells generate electricity by absorbing only the red light from the sun and that is why efficiency has always been at low levels. A recent study which was carried out at the Cambridge University, where electricity was generated by absorbing blue wavelength along with red light.

2.1      What is Photovoltaic Cell?

First and foremost, the function of a photovoltaic cell is to capture ultraviolet rays from the sun and direct the conversion of light into electricity at the atomic level. Some of the materials exhibit a property known as the photovoltaic effect that causes them to absorb photons of light and releases the electrons. The moment when these free electrons are captured, it generates electric current which is can be used as electricity. (Science.nasa.gov, 2017) [11]

There are multiple modules which can be wired together to form an array. The larger the area of a module or array, the more electricity that will be produced, and therefore creating higher watts from the ultraviolet light of the sun to the conversion of electrical energy in the photovoltaic cells. They can be connected in both series or parallel electrical arrangements, to produce any require amount of voltage and current combination. Today, the most common photovoltaic devices that are being use are single junction, or interface, to create an electric field within a semi-conductor such as a photovoltaic cell. (Science.nasa.gov, 2017)[11]

In a single-junction photovoltaic cell, only photons whose energy is equal to or greater than the band gap of the cell material can free an electron for an electric circuit. In other words, the photovoltaic response of single-junction cells is limited to the portion of the sun’s spectrum whose energy is above the band gap of the absorbing material, and lower-energy photons are not used. One way to get around this limitation is to use two (or more) different cells, whereby more than one gap and more than one junction to generate a voltage. (Science.nasa.gov, 2017) [11]

This is referred to as “multi-junction” cells (also called as “Cascade” or “Tandem” cells). Multi-junction devices can achieve a higher total conversion efficiency because they can convert more of the energy spectrum of light to electricity. A multi-junction device is a stack of individual single-junction cells in descending order of band gap. The top cells capture the high-energy photons and passes the rest of the photons on to be absorbed by lower-band gap cells. Much of today’s research in multi-junction cells focuses on Gallium Arsenide (Ga AS) as one (or all) of the component cells. Such cells have reached efficiencies of around 35% under concentrated sunlight. Other materials studied for multi-junction devices have been Amorphous Silicon and Copper Indium Dieseline. (Science.nasa.gov, 2017) [11]

Figure 1 – Shows the basic function of a solar cell. [1]

2.1.1     How silicon makes a solar cell?

Regarding to the above sub-title, a silicon based solar cell has some special chemical properties manufactured in it. A typical silicon has 14 electrons, which is arranged in three different shells:

• Firstly, two shells hold two and eight electrons respectively, are completely full.
• Then, the outer shell is only half full with just four electrons.
• A silicon atom will always look ways to fill up to its last shell, and to do this, it will share electrons with four nearby atoms.
• Lastly, that’s what forms the crystalline structure. (Pveducation.org, 2017) [9]

The biggest downside for a pure crystalline silicon is that it has poor conductor of electricity because none of its electrons are free to move about, unlike the electrons in more optimum conductors like chopper. The silicon in a solar cell has impurities, which means that other atoms purposefully mixed in with the silicon atoms. When there is heat energy coming from the ultraviolet rays of the sun and is seen entering into the silicon based material, the heat energy is added to pure silicon, which causes a few electrons to break free of their bonds and leave their atoms. These electrons, called free carriers, then wonder randomly around the crystalline lattice looking for another hole to fall into and carrying an electric current. (Pveducation.org, 2017) [9]

Figure 2 – Shows the N-type and P-type found in the silicon based PV cell. [2]

2.1.2     Anatomy of a solar cell

The basic function of a solar cell is that it requires heat or light energy in able to transmit that energy and converting it into electrical energy. Without an electric field, the cell wouldn’t work. The free electrons on the n-side see all the openings on the p-type, which causes the free electrons to compete against each other in order to fill up the opening gaps in between the n-type and p-type layers. The function of an electric field is that it acts as a diode, allowing (and even pushing) electrons to flow from the P side and the N side, but not the other way around. (Howstuffsworks.com, 2017) [9]

When the heat energy or light from the sun hits our solar cells, the energy breaks apart and falls into electron-hole pairs. Photons with enough energy will normally free one electron, resulting in another free hole for other electrons to take over. If this happens close enough to the electric field, or if free electron and free hole happen to wander into its range of influence, the field will send the electron to the N side and the hole to the P side. (Howstuffsworks.com, 2017) [9]

This causes further disruption of electrical neutrality, and if there is an external current path, electrons will flow through the path to the P side to unite with holes that the electric field send there. For an electron flow, it provides current and the cell’s electric field causes a voltage. With both the current and voltage, we can generate power, which is the product of the two. (Howstuffsworks.com, 2017) [9]

Usually a single silicon is made out of a shiny material, which can send photons bouncing away. In this kind of situation, Antireflective coating is applied onto the surface of the silicon or below of the silicon in order to reduce those losses. There are many ways in order to help to protect the cells from certain type of elements. The typical procedures in protecting the cells are usually the glass cover plate. Photovoltaic modules are generally made by connecting several individual cells together to achieve higher levels of voltage and current, and by putting those individual cells together under one study frame helps to complete the positive and negative terminals. (Howstuffsworks.com, 2017) [9]

Figure 3 – Shows the layers of a silicon based photovoltaic cells. [21]

2.1.3     Energy loss in a solar cell

• Visible light is only part of the electromagnetic spectrum. (LTD, 2017) [10]
• Electromagnetic radiation is not monochromatic, it is made up of a range of different wavelengths, and therefore energy levels. (LTD, 2017) [10]
• Light can be separated into different wavelengths, which can see in the form of a rainbow. Since light that hits our cell has photons of a wide range of energies, it turns out that some of them won’t have enough energy to alter an electron-hole pair. (LTD, 2017) [10]
• They will simply pass through the cell as if it were transparent. Still other photons have too much energy. (LTD, 2017) [10]
• Only certain electron energy, measured in electron volts (eV) and defined by our cell material (about 1.1 eV for crystalline silicon), is required to knock an electron loose. (LTD, 2017) [10]
• This is called the Band Gap Energy of a material. If a photon has more energy than the required amount, than the extra energy is lost.
• These two effects alone can account for the loss of about 70% of the radiation energy incident in our cell. (Howstuffsworks.com, 2017) [9]

• Can we use more of the photons if we use a low band gap?

: No, because our band gap also determines the strength (voltage) of our electric field, and if it is too low we make up in extra current (by absorbing more photons) which we eventually lose the photons by having a small voltage. (Howstuffsworks.com, 2017) [9]

• Power is voltage times current. The optimal band gap, balancing these two effects is around 1.4 eV for a cell made from a single material. (Howstuffsworks.com, 2017) [9]

Figure 4 – Shows the efficiency of crystalline and thin-film cells. [28]

2.2      Types of Photovoltaic Solar Cells

There are different types of Photovoltaic cells according to their manufacturing technology. The main four types of Photovoltaic cells are as follows:

1. Single or Mono Crystalline Cells

• Monocrystalline cells, which are made up of pure silicon surface and a thin structure, are known to have high efficiency. They have two different manufacturing technologies, which are: Silicon (Si) and Gallium Arsenide (GaAs).
• The Photovoltaic cells with the highest efficiency today are made of Gallium Arsenide. (Cleangreenenergyzone.com, 2017) [8]

2. Polycrystalline

• Has a crystalline structure.
• Has a manufacturing technology in the form of a thin-film.
• Cadmium Telluride (CdTe) or Copper Indium Diselenide (CIS) is used in the structure. (Cleangreenenergyzone.com, 2017) [8]

3. Amorphous Silicon

• Has a non-crystalline structure.
• Rate of efficiency is not very high.
• Used in small devices such as calculators and digital dictionaries. (Cleangreenenergyzone.com, 2017) [8]

4. Hybrid Solar Cell

• One of the newest technologies around.
• Organic and chemical substances are used together in its structure.
• Though it has quite a high rate of energy efficiency, it is not yet used in the industrial manufacturing phase. (Cleangreenenergyzone.com, 2017) [8]

Photovoltaic solar cells efficiency comparison:

• Monocrystalline Cells (Silicon): 15-20%
• Monocrystalline Cells (Gallium Arsenide): 20-35%
• Polycrystalline: 10%
• Amorphous: 7-10%
• Hybrid: 30-45%

• When it comes to manufacturing technologies the most expensive one is the hybrid Solar Cell and the cheapest one is the Amorphous Photovoltaic cells. (Cleangreenenergyzone.com, 2017) [8]

Figure 5 – Shows the different types of photovoltaic cell materials. [27]

https://www.google.co.uk/search?q=the+function+of+photovoltaic+cells&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi5xNG6i67TAhWEfFAKHRKaB54Q_AUIBygC&biw=1920&bih=969#imgrc=27nNmLTkmv45OM:

[2] https://www.google.co.uk/search?q=the+function+of+photovoltaic+cells&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi5xNG6i67TAhWEfFAKHRKaB54Q_AUIBygC&biw=1920&bih=969#imgrc=mHwNup0PeQ9wxM:

[3] Greenpowerscience.com. (2017). BUY A HUGE FRESNEL LENS GREEN POWER SCIENCE WOULD BE NICE ON THE DISCOVERY NETWORK SOLAR STIRLING ENGINES FRESNEL LENS PARABOLIC MIRROR. [online] Available at: http://www.greenpowerscience.com [Accessed 19 Apr. 2017].

[4] Inhabitant.com. (2017). inhabitant.com. [online] Available at: http://inhabitant.com [Accessed 19 Apr. 2017].

[5] RobAid. (2017). RobAid | Robots, gadgets, tech, bionics and green architecture news. [online] Available at: http://www.robaid.com [Accessed 19 Apr. 2017].

[6] Renewableenergyworld.com. (2017). Renewable Energy World Home. [online] Available at: http://renewableenergyworld.com [Accessed 19 Apr. 2017].

[7] Us, A., Maehlum, M. and Mæhlum, M. (2017). How Much Do Solar Panels Cost – Energy Informative. [online] Energy Informative. Available at: http://energyinformative.org/solar-panels-cost/ [Accessed 19 Apr. 2017].

[8] Cleangreenenergyzone.com. (2017). How Do Photovoltaic (PV) Solar Cells Work?. [online] Available at: http://cleangreenenergyzone.com/how-do-photovoltaic-pv-solar-cells-work [Accessed 19 Apr. 2017].

[9] Pveducation.org. (2017). Solar Cell Efficiency Records | PVEducation. [online] Available at: http://pveducation.org/pvcdrom/appendices/solar-cell-efficiency-results2 [Accessed 19 Apr. 2017].

[10] Howstuffsworks.com. (2017). howstuffsworks.com. [online] Available at: http://howstuffsworks.com [Accessed 19 Apr. 2017].

[11] LTD, G. (2017). Go Green. [online] Gogreen.co.uk. Available at: http://gogreen.co.uk [Accessed 19 Apr. 2017].

[12] Science.nasa.gov. (2017). How do Photovoltaics Work? | Science Mission Directorate. [online] Available at: http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells [Accessed 19 Apr. 2017].

[13] Encyclopedia Britannica. (2017). photovoltaic effect | physics. [online] Available at: http://www.britannica.com/science/photovoltaic-effect [Accessed 19 Apr. 2017].

[14] Uk.solarcontact.com. (2017). Photovoltaic effect: basic principle for the use of solar energy. [online] Available at: http://uk.solarcontact.com/photovoltaic/technology/photovoltaic-effect [Accessed 19 Apr. 2017].

[15] Uk.solarcontact.com. (2017). UK photovoltaic market: Feed-In Tariff supports domestic photovoltaic. [online] Available at: http://uk.solarcontact.com/photovoltaic/market [Accessed 19 Apr. 2017].

[16] SolarWorld. (2017). SolarWorld UK – photovoltaics, solar modules/panels. [online] Available at: http://www.solarworld-uk.co.uk [Accessed 19 Apr. 2017].

[17] Photovoltaic systems engineering by: Messenger, Roger A; Ventre, Jerry. Source: University of Hertfordshire Library Catalogue. 3rd edition, date: 2010.

[18] Solar Energy Materials and Solar Cells by:El Chaar, L; Lamont, L.A; El Zein, N. Date: 05/2012

[19] Renewable and Sustainable Energy Reviews by: Avellanda, David; Nair, M.T.S; Nair, P.K. Publisher: Elsevier, Volume: 15, Year: 2011.

[20] Thin Solid Films by: Elsevier B.V. Volume: 517, Issue: 7th edition, Date: 2009

[21] https://www.google.co.uk/search?q=the+principle+of+photovoltaic+cells&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNwsPSkrDTAhVKZ1AKHZeBCwkQ_AUIBygC&biw=1920&bih=937#imgrc=hlJBkyyiXaa3xM:

[22] https://www.google.co.uk/search?q=the+principle+of+photovoltaic+cells&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNwsPSkrDTAhVKZ1AKHZeBCwkQ_AUIBygC&biw=1920&bih=937#imgrc=hD9yzbXsidTLyM:

[23] https://www.google.co.uk/search?q=the+principle+of+photovoltaic+cells&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNwsPSkrDTAhVKZ1AKHZeBCwkQ_AUIBygC&biw=1920&bih=937#tbm=isch&q=weather+forecast+in+the+uk&imgrc=A_oJgHQ1j2fwKM:

[24] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&tbm=isch&sa=1&q=the+function+of+silicon+based+photovoltaic&oq=the+function+of+silicon+based+photovoltaic&gs_l=img.3…145188.155696.4.155941.42.26.0.0.0.0.0.0..0.0….0…1c.1.64.img..42.0.0.okx9Eqmkk74&bav=on.2,or.&dpr=1&ech=1&psi=qiX3WNiNN9DPwAKg-pioAg.1492592027913.7&ei=NSb3WMvOD9HTwAKq8rTABQ&emsg=NCSR&noj=1#imgrc=mHwNup0PeQ9wxM:

[25] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&noj=1&tbm=isch&sa=1&q=the+costs+for+photovoltaic+cells&oq=the+costs+for+photovoltaic+cells&gs_l=img.3…575677.586807.0.586926.32.30.0.2.2.0.81.1263.30.30.0….0…1c.1.64.img..0.15.671…0j0i67k1j0i30k1j0i24k1j0i10i24k1.S3bGlMzL1UY#imgrc=tJJ5PTWk8voL8M:

[26] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&noj=1&tbm=isch&sa=1&q=photovoltaic+cells+costing&oq=photovoltaic+cells+costing&gs_l=img.3…409229.412354.0.412577.9.8.0.1.1.0.68.338.8.8.0….0…1c.1.64.img..0.6.207…0j0i67k1j0i8i30k1j0i24k1.J9NzlUIuyMc#imgrc=COoHaSK0t6ibnM:

[27] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&noj=1&tbm=isch&sa=1&q=different+types+of+photovoltaic+cells&oq=different+types+of+photovoltaic+cells&gs_l=img.3..0i24k1.466401.472349.0.472445.37.13.0.24.24.0.67.595.13.13.0….0…1c.1.64.img..0.37.678…0j0i67k1.MfeD4PR1W2w#imgdii=dVstJ5Yu5XIqIM:&imgrc=6NSiyI8L9EIwVM:

[28] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&noj=1&tbm=isch&sa=1&q=different+types+of+photovoltaic+cells&oq=different+types+of+photovoltaic+cells&gs_l=img.3..0i24k1.466401.472349.0.472445.37.13.0.24.24.0.67.595.13.13.0….0…1c.1.64.img..0.37.678…0j0i67k1.MfeD4PR1W2w#imgrc=LtPprXrsouIecM:

[29] https://www.google.co.uk/search?client=firefox-b-ab&biw=1920&bih=937&noj=1&tbm=isch&sa=1&q=renewable+energy&oq=renewa&gs_l=img.3.0.0i67k1j0j0i67k1l3j0j0i67k1j0l2j0i67k1.310976.311952.0.314868.6.6.0.0.0.0.74.346.6.6.0….0…1c.1.64.img..0.6.341.quoIbXLURxo#imgdii=EAL9JHAO7hJyOM:&imgrc=zSg7JiuiIOD8TM: