MT5009 ANALYZING HI-TECHNOLOGY OPPORTUNITIESCIGS Solar Cells<br />Zhang Xuan (a0068215)<br />Rajendiran Aravind Raj (a0065...
  Outline<br />
Motivation<br />Motivation<br />Solar energy is the most abundant energy and free of cost<br /><ul><li>Solar energy is a s...
Solar cell is a commercially available and reliable technology with a significant potential for long-term growth in nearly...
  Outline<br />
Technology Paradigm of Solar Cells<br />Crystalline silicon (c-Si) 85-90% market share<br /><ul><li>Cells are typically ma...
Cell contacts, emitter and passivation
Improve device structure and develop new device with novel concept
Wafer equivalent technologies
Productivity and cost optimization</li></ul>Limitation for paradigm<br /><ul><li>The theoretical limit for a crystalline s...
The thickness of silicon wafer is hard to reduce</li></li></ul><li>Technology Paradigm of Solar Cells<br />Thin films 10-1...
Cell structure improvement
High rate deposition in large area
Defects and nanostructure improvement</li></ul>Limitation of paradigm<br /><ul><li>Light trapping efficiency
Band gap & grain size
Low-lifetime of thin film, sensitive to moisture
  Thermo-physical properties of layers and substrates</li></li></ul><li>Technology Paradigm of Solar Cells<br />Concentrat...
Solar tracking system
Optic concentration</li></ul>Novel technologies<br />Develop active layers which best match the solar spectrum or which mo...
Processing</li></li></ul><li>Different PV technologies market share<br />
Different PV technologies market share<br />
CIGS Thin Film Solar Cell<br />CIGS Technology: <br /><ul><li>Copper indium gallium (di)selenide (CuInxGa(1-x)Se2)
I-III-VI2 compound semiconductor material 
Direct band gap material
Multicrystalline nature
Band gap can be varied from 1.0 eV to 1.7 eV
Light absorber (Active Layer) material for TFSC</li></li></ul><li>  Outline<br />
CIGS Value Proposition <br /><ul><li>Short energy pay back time and less energy consuming process(1/3 of silicon)
Adaptability - transferable know how from existing industry
LCD industry technology
Lightweight and light bulk, Can be manufactured on flexible substrate
lead to niche market applications. E.g. BIPV
Less environmental footprint for recycling for CIGS
Green technology compared with silicon solar cell</li></li></ul><li>          CIGS –Working Principle <br />Light shining ...
                    Why CIGS has high efficiency than other thin films? <br />By adjusting ratio of CIGS mixture , the bro...
  Outline<br />
  Does the CIGS has reached maximum efficiency ?<br />     CIGS absorber layer  quantum efficiency might have reached satu...
  Improvements in components<br /><ul><li>  Buffer layer  CdS can be modified using ZnS, InS, ZnSe etc  (Voc,Isc)
   An anti reflective layer is used to reduce front surface reflection loss( Pin)
   Contacts can be made thinner /transparent  to allow more sunlight to reach the                       cell and low resis...
Improvements in modules<br />   CIGS  <br />* Laser scribing * Monolithic fabrication * More transparent , less absorption...
  Improvements in Systems<br />Controversies between research and industrial results !<br /><ul><li>Needs duplication of e...
  Uniform & quality deposition of thin films over large area
  Role of contaminants and some unexplained stories too….</li></ul>Courtesy: Global Solar<br />
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CIGS Solar Cells: How and Why is their Cost Falling?

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My master's students use concepts from my (Jeff Funk) forthcoming book (Technology Change and the Rise of New Industries) to analyze the economic feasibility of CIGS (Cadmium Indium Gallium Selenide) Solar Cells. Improvements in efficiencies and reductions in cost per area (through new processes and increasing the substrate size) are causing steady reductions in the cost of electricity from them. See my other slides for details on concepts, methodology, and other new industries..

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  • Interesting - thank you for sharing! Any update on hos CIGS will compete with c-Si after Yingli announced prices as low as 0.74 USD/W for theis c-Si modules for April 2012?
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  • Today, PV provides 0.1% of total global electricity generation. However, PV is expanding very rapidly due to effective supporting policies and recent dramatic cost reductions. In the IEA solar PV roadmap vision, PV is projected to provide 5% of global electricity consumption in 2030, rising to 11% in 2050
  • A p-n junction is formed by placing p-type and n-type semiconductors next to one another. The p-type, with one less electron, attracts the surplus electron from the n-type to stabilize itself. Thus the electricity is displaced and generates a flow of electrons, otherwise known as electricity. When sunlight hits the semiconductor, an electron springs up and is attracted toward the n-type semiconductor. This causes more negatives in the n-type semiconductors and more positives in the p-type, thus generating a higher flow of electricity. This is the photovoltaic effect.For crystal-growth feedstock, the c-Si PV industry has been relying on waste material from the semiconductor Si industry and on secondary polysilicon, the excess or rejected material from electronic-grade polysilicon production. This amounts to about 10% of the polysilicon material used by the semiconductor Si industry
  • Thin-film silicon cells have become popular due to cost, flexibility, lighter weight, and ease of integration, compared to wafer silicon cells.Thin film is a process where material from a target source is coated onto a substrate via a plasma field. These thin films are minuscule — angstroms to microns thick — and therefore use a very small amount of material to achieve most coating thickness goals.Active materials: CdS and CdTe converts sun energy to electricityTCO layer: allows light to pass through to the active materials while being electrically conductiveGlass: provide mechanical strength and protection against weather elementsAmorphous silicon (a-Si) and other thin film silicon (TF-Si)Cadmium Telluride (CdTe)Copper indium gallium selenide (CIS or CIGS)Dye-sensitized solar cell and other organic solar cell
  • direct solar radiation can be concentrated by optical means and used in concentrator solar cell technologies. Considerable research has been undertaken in this high-efficiency approach because of the attractive feature of the much smaller solar cell area required. Low and medium concentration systems (up to 100 suns) work with high-efficiency silicon solardeveloping active layers which best match the solar spectrum or which modify the incoming solar spectrum. Both approaches build on progress in nanotechnology and nano-materials. Quantum wells, quantum wires and quantum dots are examples of structures introduced in the active layer. Further approaches deal with the collection of excited charge carriers (hot carrier cells) and the formation of intermediate band gaps.
  • The abbreviation CIS stands for copper indium diselenide and CIGS for copper indium gallium diselenide. The x describes the ratio between indium and gallium.CIS and CIGS are compound semiconductors of the I-III-VI group.The band-gap structure is a complex heterojunction system.That means that thejunction is formed by different semiconducting materials with unequal band gaps.
  • These thin film solar cells show efficiencies of 19% in the case of small area modules in laboratory and of about 13 % in large area modules.They show a very good stability in outdoor tests concerning mechanical load and radiation hardness against electrons and protons.CIGS has no intrinsic degradation mechanisms can be limited to a very small proportion by effective encapsulation. CIGS PV manufacturers are currently targeting module lives of 30 years.
  • Thin-film solar cells are created by depositing several layers of a light-absorbing material (a semiconductor) onto a substrate such as coated glass, metal, or plastic. These semiconductor layers don&apos;t have to be thick because they can absorb solar energy very efficiently. As a result, thin-film solar cells require less materials to manufacture, are flexible, and are therefore suitable for many applications that crystalline cells are not. Thin-film can also be manufactured in a large-area process, which can be an automated, continuous production process, and therefore has the potential to significantly reduce manufacturing costs.
  • CIGS Solar Cells: How and Why is their Cost Falling?

    1. 1. MT5009 ANALYZING HI-TECHNOLOGY OPPORTUNITIESCIGS Solar Cells<br />Zhang Xuan (a0068215)<br />Rajendiran Aravind Raj (a0065709)<br />Wu Yiming (a0068957)<br />21/04/2011<br />
    2. 2. Outline<br />
    3. 3. Motivation<br />Motivation<br />Solar energy is the most abundant energy and free of cost<br /><ul><li>Solar energy is a safer, environmental friendly resource to solve energy crisis, and environmental problems
    4. 4. Solar cell is a commercially available and reliable technology with a significant potential for long-term growth in nearly all world regions</li></li></ul><li>Motivation<br /><ul><li>Solar cell is projected to provide 5% of global electricity consumption in 2030, rising to 11% in 2050</li></ul>Silicon material<br /> price decreased<br />Source: IEA solar PV roadmap <br />
    5. 5. Outline<br />
    6. 6. Technology Paradigm of Solar Cells<br />Crystalline silicon (c-Si) 85-90% market share<br /><ul><li>Cells are typically made using a crystalline silicon wafer (ingots can be monocrystalline or multicrystalline)</li></ul>Basic Operation<br /><ul><li>Silicon crystals are laminated into n-type and p-type layers, stacked on top of each other. Light striking the crystals induces the “photovoltaic effect,” which generates electricity</li></ul>Methods to improve<br /><ul><li>New silicon materials and processing
    7. 7. Cell contacts, emitter and passivation
    8. 8. Improve device structure and develop new device with novel concept
    9. 9. Wafer equivalent technologies
    10. 10. Productivity and cost optimization</li></ul>Limitation for paradigm<br /><ul><li>The theoretical limit for a crystalline silicon solar cell is ~ 29%.
    11. 11. The thickness of silicon wafer is hard to reduce</li></li></ul><li>Technology Paradigm of Solar Cells<br />Thin films 10-15% market share<br />Made by depositing one or more thin layers (thin film) of photovoltaic materials on a substrate. Photovoltaic material convert sun energy to electricity.<br /> a-Si and uc-Si CdTe CIS or CIGS Dye-sensitized solar cell <br />Methods to improve<br /><ul><li>Improve quality of substrates and transparent conductive oxides
    12. 12. Cell structure improvement
    13. 13. High rate deposition in large area
    14. 14. Defects and nanostructure improvement</li></ul>Limitation of paradigm<br /><ul><li>Light trapping efficiency
    15. 15. Band gap & grain size
    16. 16. Low-lifetime of thin film, sensitive to moisture
    17. 17. Thermo-physical properties of layers and substrates</li></li></ul><li>Technology Paradigm of Solar Cells<br />Concentrating PV<br />CPV systems use optics to concentrate a large amount of sunlight onto a small area of solar photovoltaic materials to generate electricity.<br />High cost with super high efficiency (can reach 50%)<br />Methods to improve<br /><ul><li>Semiconductor properties
    18. 18. Solar tracking system
    19. 19. Optic concentration</li></ul>Novel technologies<br />Develop active layers which best match the solar spectrum or which modify the incoming solar spectrum. Both approaches build on progress in nanotechnology and nano-materials. <br />Structures of the active layer - quantum wells, quantum wires and quantum dots.<br />Key issues - collection of excited charge carriers (hot carrier cells) and the formation of intermediate band gaps.<br />Ultra-high efficiency with full spectrum utilization<br />Methods to improve<br /><ul><li>Characterization and modeling of especially nano-structured materials and devices
    20. 20. Processing</li></li></ul><li>Different PV technologies market share<br />
    21. 21. Different PV technologies market share<br />
    22. 22. CIGS Thin Film Solar Cell<br />CIGS Technology: <br /><ul><li>Copper indium gallium (di)selenide (CuInxGa(1-x)Se2)
    23. 23. I-III-VI2 compound semiconductor material 
    24. 24. Direct band gap material
    25. 25. Multicrystalline nature
    26. 26. Band gap can be varied from 1.0 eV to 1.7 eV
    27. 27. Light absorber (Active Layer) material for TFSC</li></li></ul><li> Outline<br />
    28. 28. CIGS Value Proposition <br /><ul><li>Short energy pay back time and less energy consuming process(1/3 of silicon)
    29. 29. Adaptability - transferable know how from existing industry
    30. 30. LCD industry technology
    31. 31. Lightweight and light bulk, Can be manufactured on flexible substrate
    32. 32. lead to niche market applications. E.g. BIPV
    33. 33. Less environmental footprint for recycling for CIGS
    34. 34. Green technology compared with silicon solar cell</li></li></ul><li> CIGS –Working Principle <br />Light shining on the solar cell produces both a current and a voltage to generate electric power.<br /> Generation of light-generated carriers<br />Collection of the light-generated carriers to generate a electric current<br /> N Type<br /> P Type <br />Generation of a large voltage across the solar cell<br />CIGS Solar cell<br /> Dissipation of power in the load<br />
    35. 35.
    36. 36. Why CIGS has high efficiency than other thin films? <br />By adjusting ratio of CIGS mixture , the broad energy band distribution can be achieved. CIGS absorb light of different wavelengths in solar spectrum. It has wide solar spectrum response and is capable of fully utilizing incident light compared to it competitors . <br />% I can absorb more light than other thin films – CIGS %<br />Courtesy : AUO Solar<br />
    37. 37. Outline<br />
    38. 38. Does the CIGS has reached maximum efficiency ?<br /> CIGS absorber layer quantum efficiency might have reached saturation, but improvements can be done in cell structure and materials used for fabrication to increase efficiency. End user is concerned about cost also.<br />
    39. 39. Improvements in components<br /><ul><li> Buffer layer CdS can be modified using ZnS, InS, ZnSe etc (Voc,Isc)
    40. 40. An anti reflective layer is used to reduce front surface reflection loss( Pin)
    41. 41. Contacts can be made thinner /transparent to allow more sunlight to reach the cell and low resistivity materials can be considered. (21 % without contacts)</li></li></ul><li> Improvements in components<br />CIGSSe Technology Tandem Cell Structure <br /> Source : Univ. of Johannesburg Source : NREL <br />
    42. 42. Improvements in modules<br /> CIGS <br />* Laser scribing * Monolithic fabrication * More transparent , less absorption <br /> glass for lamination* Ink based printing technology <br /> on flexible substrates<br />* BOS improvements<br /> Cell<br />Module<br /> Substrate<br />
    43. 43. Improvements in Systems<br />Controversies between research and industrial results !<br /><ul><li>Needs duplication of equipments used for research in larger scale
    44. 44. Uniform & quality deposition of thin films over large area
    45. 45. Role of contaminants and some unexplained stories too….</li></ul>Courtesy: Global Solar<br />
    46. 46. Latest CIGS Update<br /> Research<br />Industry <br />Efficiency : 20.3 %<br />Area : 0.5 sq.cms<br />Centre for Solar Energy and Hydrogen Research <br />ZSW<br />Efficiency : 15.7 %<br />Area : 1 sq.m<br />MiaSolé<br />
    47. 47. Outline<br />
    48. 48. Cost & Efficiency Analysis <br />
    49. 49. Cost: CIGS < c-Si? Manufacturing Steps <br /> CIGS Solar Cell<br />Si – Wafer Solar Cell<br />Module<br /> Cell<br /> Cell<br /> Substrate<br />Module<br /> Substrate<br />The monolithic integration of thin-film PV can lead to significant manufacturing cost reduction compared to c-Si technology.<br />
    50. 50. Cost Comparisons for thin film Solar Panels<br />
    51. 51. Cost: a-Si vs. CIGS & CdTe<br /> a-Si has the lowest manufacturing costs/watt, but its low conversion efficiencies, <10%, require a greater investment in the BOS components, the supporting infrastructure that includes mounting structures, inverters and electrical wiring.  <br /> By contrast, CIGS and CdTe have demonstrated efficiencies approaching and exceeding a-Si.<br />a-Si<br />CIGS<br />CdTe<br />
    52. 52. Cost: CIGS > CdTe<br /><ul><li>CIGS and CdTe cells share common characteristics and device structural elements.
    53. 53. In principle, the cost/area should be similar, thus, efficiency becomes a crucial factor for cost/watt.
    54. 54. However, production processes in terms of throughput and yield can differ significantly and may offset the advantage of higher performance.
    55. 55. Its production is not easy as four different materials are used.
    56. 56. This is the reason why CdTe has low cost advantage over CIGS.</li></li></ul><li>Low Cost Processing of CIGS[1]<br /><ul><li>Conventional best-performing CIGS deposition processes:
    57. 57. co-evaporation
    58. 58. by sputtering of the metals, followed by selenization with H2Se.
    59. 59. These two processes suffer from relatively slow throughput, poor material utilization, and relatively high vacuum.
    60. 60. One such example is a process that uses nano-components to make printable precursors that are crystallized into CIGS.
    61. 61. Need for Low-Cost, High-Throughput Processes.
    62. 62. A lower-cost process should feature high deposition rates, high material utilization, and simpler equipment capable of processing very large substrates.</li></ul>Used by Global Solar and Wurth Solar<br />Reference: M. Kaelin, Low cost processing of CIGS thin film solar cells, solar energy, 2004<br />
    63. 63. Low Cost Processing of CIGS[2]<br />Non-vacuum absorber formation techniques<br />Often poor quality, includes impurity phases and may be amorphous or microcrystalline due to the low deposition T (<400 °C)<br />Quality improved, material is annealed at a higher temperature<br />Reference: M. Kaelin, Low cost processing of CIGS thin film solar cells, solar energy, 2004<br />
    64. 64. Low Cost Processing of CIGS[3]<br /><ul><li>Chemical spay pyrolysis</li></ul>One of the best-investigated non-vacuum deposition processes, but few results were reported.<br /><ul><li>Pros: Very suited for uniform large area coating.
    65. 65. Cons: Impurity phases, Traces from reaction by-products, Small grain-size obtained.
    66. 66. Paste coating</li></ul>Typically includes screen printing, doctor-blade coating and curtain coating.<br /><ul><li>A fast process can be applied to continuous roll-to-roll deposition.
    67. 67. Very efficient use of material, exhibits high packing densities.
    68. 68. Does not require expensive vacuum equipment, manufacturing cost per square meter is significantly lower compared to vacuum deposited absorber layers.</li></ul>Reference: M. Kaelin, Low cost processing of CIGS thin film solar cells, solar energy, 2004<br />
    69. 69. V<br />V<br />electrolyte<br />anode<br />The Electrodeposition Process<br /><ul><li>SoloPower has developed a low cost electro-deposition process to manufacture CIGS solar cells and modules
    70. 70. A conversion efficiency approaching 14% has been confirmed at NREL
    71. 71. Modules have been manufactured demonstrating process flow</li></ul>Reference: Rommel Noufi, Thin Film CIGS Photovoltaics, SoloPower, Inc.<br />
    72. 72. The Electrodeposition Process<br /><ul><li>Hardware is low cost
    73. 73. Can be high throughput once the hardware is tuned to the specifics of the process
    74. 74. Near 100% material utilization
    75. 75. Pre-formed expensive materials are not required, e.g. sputtering targets, nano-particles
    76. 76. Crystallographically oriented CIGS films with good morphology and density have been demonstrated
    77. 77. Thickness and composition control of the deposited films are integral part of the process
    78. 78. Readily scalable</li></ul>Reference: Rommel Noufi, Thin Film CIGS Photovoltaics, SoloPower, Inc.<br />
    79. 79. ISET’s Ink-based Fabrication of CIGS<br /><ul><li>International Solar Electric Technology
    80. 80. Currently developed a novel ink printing method for fabricating CIGS thin-film solar cells.
    81. 81. Significantly lower manufacturing costs than all current solar cell technologies.
    82. 82. Combines the following advantages to achieve low costs
    83. 83. Exceptional utilization of materials
    84. 84. Low capital equipment expenses
    85. 85. Application over various area formats due to versatility printing
    86. 86. Excellent compositional uniformity established within ink formation, resulting in high production yields
    87. 87. Adaptability to flexible substrates
    88. 88. Efficiency reaching above 14%, with large potential for performance improvements.
    89. 89. Robust module architecture that reduces assembly costs and minimizes field service failures.</li></ul>Reference: Competitiveness of Ink-Based Thin-Film Photovoltaics, Advantages of ISET’s Printed CIGS over other Current Photovoltaic Technologies<br />
    90. 90. ISET’s Monolithically Integrated CIGS Modules<br />Reference: Competitiveness of Ink-Based Thin-Film Photovoltaics, Advantages of ISET’s Printed CIGS over other Current Photovoltaic Technologies<br />
    91. 91. ISET’s Ink-based Fabrication of CIGS<br />bare glass<br />metalized glass<br />ink-coated substrate<br />final CIGS module<br />Ink-Based CIGS Production Process Sequence – very simple<br />Reference: Competitiveness of Ink-Based Thin-Film Photovoltaics, Advantages of ISET’s Printed CIGS over other Current Photovoltaic Technologies<br />
    92. 92. ISET’s Printed CIGS vs. High-Vacuum CIGS<br />Reference: Competitiveness of Ink-Based Thin-Film Photovoltaics, Advantages of ISET’s Printed CIGS over other Current Photovoltaic Technologies<br />
    93. 93. ISET’s Monolithically Integrated CIGS Modules<br />Reference: Competitiveness of Ink-Based Thin-Film Photovoltaics, Advantages of ISET’s Printed CIGS over other Current Photovoltaic Technologies<br />
    94. 94. Outline<br />
    95. 95. Future opportunities<br />Direct opportunities - applications<br /><ul><li>Solar power plants (lightweight, light bulk and flexibility enables to install in more harsh places)
    96. 96. Power supplies for satellites and space vehicles (high efficiency and radiation hardness)
    97. 97. Decentralized power supply - Building Integrated PV, foldable or rollable panels (flexible substrate and light bulk)
    98. 98. transparent substrates apply to large areas like windows
    99. 99. thin substrate can be painted onto aircraft wings
    100. 100. Power supply for portable purposes (lightweight and high efficiency)
    101. 101. Consumer products such as watches, toys and calculators
    102. 102. Power supply for emergency and remote areas (durability and high efficiency)
    103. 103. solar powered water pumping & water treatment system
    104. 104. remote lighting system & PV powered electric fencing
    105. 105. telecommunications and remote monitoring Systems
    106. 106. PV powered storage batteries, vehicles and traffic control signal
    107. 107. vaccine and blood storage refrigerators for remote areas </li></ul>http://www.baulinks.de/webplugin/2007/i/0732-wuerthsolar1.jpg<br />http://www.copper.org/innovations/2007/05/images/civilian_flex_panel.jpg<br />http://www.esa.int/images/ISS_2004_web400.jpg<br />http://www.rgp.ufl.edu/publications/explore/v12n2/images/thin-film.jpg<br />
    108. 108. CIGS solar cell value chain <br />opportunities lie in each segment of the chain<br />Entrepreneurial Opportunities<br />
    109. 109. Material and chemical supplier <br />For CIGS solar cell manufacturing, process control starts with the material: the target.<br />If process starts with inadequate material, process will yield inadequate results.<br /><ul><li>CIGS absorber layer materials - elemental copper, indium, gallium, selenium
    110. 110. Individual components that make up the CIGS layer - inks, nanoparticles
    111. 111. Suspension solvents and additives such as resins and wetting agents
    112. 112. Other materials - transparent conductive oxides (TCOs), molybdenum and zinc oxide used </li></ul> for the contacts<br /><ul><li>New materials substitutes used in non-vacuum deposition of the electrode layers</li></ul>Flexible substrate - Cheaper, Flexible and Larger <br /><ul><li>Encapsulation Materials – make multiple alternating layers </li></ul> of polymer and ceramic films<br /><ul><li>Ultrathin, Flexible Glass and Glass‐like Composites
    113. 113. Polyimide Films – dominated by polymer substrates</li></ul>Entrepreneurial Opportunities<br />
    114. 114. Material and chemical supplier <br />For CIGS solar cell manufacturing, process control starts with the material: the target.<br />If process starts with inadequate material, process will yield inadequate results.<br /><ul><li>CIGS absorber layer materials - elemental copper, indium, gallium, selenium
    115. 115. Individual components that make up the CIGS layer - inks, nanoparticles
    116. 116. Suspension solvents and additives such as resins and wetting agents
    117. 117. Other materials - transparent conductive oxides (TCOs), molybdenum and zinc oxide used </li></ul> for the contacts<br /><ul><li>New materials substitutes used in non-vacuum deposition of the electrode layers</li></ul>Flexible substrate - Cheaper, Flexible and Larger <br /><ul><li>Encapsulation Materials – make multiple alternating layers </li></ul> of polymer and ceramic films<br /><ul><li>Ultrathin, Flexible Glass and Glass‐like Composites
    118. 118. Polyimide Films – dominated by polymer substrates</li></ul>Entrepreneurial Opportunities<br />
    119. 119. Entrepreneurial Opportunities<br />Opportunities for Solar Panel Firms and Service Firm<br /><ul><li>Installation and maintenance of solar panels and solar energy products - hardware engineers, turnkey system integrators and trainers
    120. 120. Outside firms like roof and building firms come in as BIPV installer
    121. 121. Training people for the solar energy industry
    122. 122. Trading of solar panels and a range of solar energy products</li>
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