The Evolving Landscape of Photovoltaic Technology: Implications for UK Housing and Grid Integration

Abstract

Photovoltaic (PV) technology is experiencing a period of rapid development, driven by the urgent need for decarbonization and the declining costs of solar energy. This report provides a comprehensive overview of the evolving landscape of PV technology, focusing on its implications for UK housing and the integration of solar energy into the national grid. We examine various PV technologies, including crystalline silicon (c-Si), thin-film, and emerging perovskite-based solar cells, analyzing their performance characteristics, manufacturing processes, and environmental impacts. Furthermore, we delve into the challenges and opportunities associated with integrating large-scale solar energy into the UK grid, considering factors such as grid stability, energy storage solutions, and policy frameworks. The report also investigates the potential of building-integrated photovoltaics (BIPV) and community-based solar initiatives in the UK context, evaluating their economic viability and contribution to renewable energy targets. Finally, we discuss future trends in PV technology, including tandem solar cells, bifacial modules, and advanced materials, and their potential to revolutionize the solar energy sector in the UK and beyond. The context of the ‘Sunshine Bill’ is considered, acknowledging how these technologies could contribute to a more sustainable future.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

1. Introduction

The imperative to mitigate climate change and reduce reliance on fossil fuels has propelled the rapid growth of renewable energy technologies, with solar photovoltaic (PV) systems at the forefront. The UK, committed to achieving net-zero emissions by 2050, recognizes the pivotal role of solar energy in its energy transition. However, the effective deployment of PV technology in the UK context presents unique challenges and opportunities, influenced by factors such as the UK’s climate, housing stock, and existing grid infrastructure. The rejected ‘Sunshine Bill’ underscores the complexities of implementing large-scale solar initiatives and highlights the need for a holistic understanding of the technological, economic, and policy considerations involved. This report aims to provide a comprehensive analysis of the evolving landscape of PV technology, focusing on its relevance to UK housing and the seamless integration of solar energy into the national grid. The report delves into the underlying science of various PV technologies, their performance metrics, manufacturing processes, environmental impacts, and the latest innovations driving the field forward. Furthermore, it explores the challenges and opportunities associated with grid integration, energy storage, and policy frameworks that are crucial for maximizing the benefits of solar energy in the UK. The context of the ‘Sunshine Bill’ serves as a point of reference, examining how the technologies discussed could have contributed to the Bill’s objectives and addressing the reasons for its rejection.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

2. Crystalline Silicon Solar Cells: Dominance and Advancements

Crystalline silicon (c-Si) solar cells currently dominate the global PV market, accounting for over 90% of installed capacity. This dominance is attributed to their relatively high efficiency, established manufacturing processes, and long-term reliability. c-Si solar cells are typically manufactured from either monocrystalline silicon (mono-Si) or multicrystalline silicon (multi-Si) wafers. Mono-Si cells, produced from a single crystal of silicon, exhibit higher efficiencies (typically in the range of 20-24%) compared to multi-Si cells (typically in the range of 16-20%). However, mono-Si cells are generally more expensive to manufacture due to the complex crystal growth process. Recent advancements in c-Si technology have focused on improving efficiency, reducing manufacturing costs, and enhancing long-term stability. These advancements include:

• Passivated Emitter and Rear Cell (PERC) Technology: PERC technology involves the addition of a dielectric passivation layer on the rear surface of the solar cell, reducing surface recombination losses and improving efficiency. PERC cells have become the industry standard for high-efficiency c-Si modules.
• Heterojunction Technology (HJT): HJT solar cells incorporate thin layers of amorphous silicon to passivate the surface of the crystalline silicon wafer, further reducing recombination losses and achieving even higher efficiencies. HJT cells are particularly attractive for bifacial module applications.
• Tunnel Oxide Passivated Contact (TOPCon): TOPCon cells are similar to PERC cells but use an ultra-thin tunneling oxide layer and a doped polysilicon layer for surface passivation, leading to higher efficiencies and improved reliability.
• Bifacial Modules: Bifacial modules are designed to capture sunlight from both the front and rear surfaces, increasing energy yield and reducing the levelized cost of energy (LCOE). Bifacial modules are particularly effective in environments with high albedo, such as snow-covered regions or rooftops with reflective surfaces.

While c-Si technology continues to evolve, its limitations include its relatively high manufacturing energy requirements and its susceptibility to degradation under high temperatures and humidity. Furthermore, the silicon supply chain is concentrated in a few countries, raising concerns about supply chain security and geopolitical risks.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

3. Thin-Film Solar Cells: Diversification and Novel Materials

Thin-film solar cells offer an alternative to c-Si technology, with the potential for lower manufacturing costs and greater flexibility. Thin-film cells are fabricated by depositing thin layers of semiconductor materials onto a substrate, such as glass, stainless steel, or flexible polymers. The main types of thin-film solar cells include:

• Cadmium Telluride (CdTe): CdTe solar cells are the most commercially successful thin-film technology, offering competitive efficiencies (typically in the range of 16-20%) and low manufacturing costs. However, CdTe cells face concerns regarding the toxicity of cadmium and the environmental impact of their disposal.
• Copper Indium Gallium Selenide (CIGS): CIGS solar cells offer high efficiencies (typically in the range of 18-22%) and good long-term stability. CIGS cells are also less susceptible to degradation under high temperatures and humidity compared to c-Si cells. However, the manufacturing process for CIGS cells is more complex and requires precise control of the elemental composition.
• Amorphous Silicon (a-Si): a-Si solar cells were among the first thin-film technologies to be commercialized. They offer low manufacturing costs and can be deposited on flexible substrates. However, a-Si cells suffer from the Staebler-Wronski effect, which causes a significant decrease in efficiency over time.

Thin-film solar cells offer several advantages over c-Si cells, including lower manufacturing costs, greater flexibility, and the potential for building-integrated photovoltaics (BIPV). However, they also face challenges such as lower efficiencies, potential environmental concerns (in the case of CdTe), and limited market share compared to c-Si technology. Recent research has focused on developing new thin-film materials with improved efficiencies and reduced environmental impacts, such as copper zinc tin sulfide (CZTS) and perovskite-inspired thin films.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

4. Perovskite Solar Cells: A Disruptive Technology

Perovskite solar cells have emerged as a disruptive technology in the PV field, exhibiting remarkable efficiency gains in a short period of time. Perovskites are a class of materials with a specific crystal structure that enables efficient light absorption and charge transport. Perovskite solar cells have achieved efficiencies exceeding 25% in laboratory settings, surpassing many established PV technologies. However, perovskite solar cells face challenges regarding long-term stability and the use of toxic materials, such as lead.

Research efforts are focused on addressing these challenges through:

• Improving Stability: Encapsulation techniques, compositional engineering, and interface modification are being explored to enhance the stability of perovskite solar cells under various environmental conditions, such as humidity, temperature, and UV radiation.
• Developing Lead-Free Perovskites: Researchers are actively investigating lead-free perovskite materials, such as tin-based and bismuth-based perovskites, to mitigate the environmental concerns associated with lead toxicity. However, lead-free perovskites typically exhibit lower efficiencies compared to lead-based perovskites.
• Tandem Solar Cells: Tandem solar cells combine perovskites with other PV materials, such as silicon or CIGS, to achieve higher efficiencies than single-junction solar cells. Tandem solar cells can overcome the Shockley-Queisser limit, which restricts the maximum efficiency of single-junction solar cells.

Perovskite solar cells hold immense potential for revolutionizing the PV industry, offering the prospect of high-efficiency, low-cost solar energy. However, significant research and development efforts are still required to address the stability and environmental concerns associated with this technology before it can be widely deployed.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

5. Building-Integrated Photovoltaics (BIPV): Towards Energy-Neutral Buildings

Building-integrated photovoltaics (BIPV) refers to the integration of PV modules into the building envelope, such as roofs, facades, and windows. BIPV systems can serve as both a source of renewable energy and a functional building material, reducing the need for conventional building materials and improving the energy efficiency of buildings. BIPV systems offer several advantages over conventional rooftop solar panels, including:

• Aesthetics: BIPV systems can be designed to seamlessly integrate with the building architecture, enhancing the aesthetic appeal of buildings.
• Functionality: BIPV systems can provide shading, insulation, and weather protection, reducing the energy consumption of buildings.
• Cost Savings: BIPV systems can reduce the cost of building materials and energy bills, leading to long-term cost savings.

However, BIPV systems also face challenges such as higher installation costs, complex design requirements, and limited standardization. The UK housing stock, characterized by diverse architectural styles and building materials, presents both opportunities and challenges for BIPV adoption. The ‘Sunshine Bill’, had it passed, could have encouraged BIPV adoption through subsidies or mandates. Overcoming these challenges requires collaboration between architects, engineers, and PV manufacturers to develop innovative BIPV solutions that are both aesthetically pleasing and economically viable.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

6. Grid Integration Challenges and Solutions

The increasing penetration of solar energy into the UK grid poses significant challenges to grid stability and reliability. Solar energy is intermittent and dependent on weather conditions, which can lead to fluctuations in power generation and voltage instability. To address these challenges, several solutions are being implemented, including:

• Energy Storage: Energy storage systems, such as batteries and pumped hydro storage, can store excess solar energy during periods of high generation and release it during periods of low generation, smoothing out the variability of solar energy and improving grid stability.
• Demand Response: Demand response programs incentivize consumers to reduce their electricity consumption during peak demand periods, reducing the strain on the grid and enabling greater integration of solar energy.
• Smart Grids: Smart grids incorporate advanced sensors, communication technologies, and control systems to monitor and manage the flow of electricity in real-time, enabling greater flexibility and resilience of the grid.
• Grid Reinforcement: Grid reinforcement involves upgrading existing grid infrastructure, such as transmission lines and substations, to accommodate the increased flow of electricity from solar energy sources.

The UK government has set ambitious targets for renewable energy deployment, which will require significant investments in grid infrastructure and energy storage. Furthermore, effective policy frameworks and regulatory mechanisms are needed to incentivize grid integration and ensure the reliable and affordable supply of electricity.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

7. The UK Solar Panel Manufacturing Landscape and Supply Chain Dynamics

Currently, the UK has a limited solar panel manufacturing capacity, relying heavily on imports from other countries, particularly China. This dependence raises concerns about supply chain security, geopolitical risks, and the environmental impact of transportation. Establishing a robust domestic solar panel manufacturing industry in the UK would offer several benefits, including:

• Job Creation: A domestic solar panel manufacturing industry would create new jobs in manufacturing, research and development, and installation.
• Economic Growth: A domestic solar panel manufacturing industry would boost economic growth and reduce reliance on imports.
• Supply Chain Security: A domestic solar panel manufacturing industry would enhance supply chain security and reduce vulnerability to geopolitical risks.
• Innovation: A domestic solar panel manufacturing industry would foster innovation and the development of new solar technologies.

However, establishing a competitive solar panel manufacturing industry in the UK requires significant investments in research and development, manufacturing infrastructure, and workforce training. The government could play a crucial role in supporting the development of a domestic solar panel manufacturing industry through policies such as tax incentives, subsidies, and research grants. Moreover, it is essential to develop sustainable and ethical supply chains for raw materials and components used in solar panel manufacturing.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

8. Future Trends and Innovations

The PV industry is undergoing continuous innovation, with several promising technologies on the horizon. These include:

• Tandem Solar Cells: As previously mentioned, tandem solar cells combine two or more different PV materials to absorb a wider range of the solar spectrum, achieving higher efficiencies than single-junction solar cells. Perovskite-silicon tandem solar cells are particularly promising.
• Bifacial Modules: Bifacial modules are becoming increasingly popular due to their ability to capture sunlight from both the front and rear surfaces, increasing energy yield and reducing the LCOE.
• Advanced Materials: Researchers are exploring new materials for solar cells, such as quantum dots, organic semiconductors, and metal halide perovskites, which offer the potential for high efficiencies, low costs, and flexible designs.
• Artificial Intelligence (AI): AI is being used to optimize the design, manufacturing, and operation of solar panels, improving efficiency, reliability, and performance. AI can also be used to predict solar energy generation and optimize grid integration.

These future trends and innovations have the potential to further reduce the cost of solar energy, improve its efficiency, and enhance its integration into the UK energy system. The UK government should continue to support research and development in these areas to maintain its competitiveness in the global PV market.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

9. Conclusion

Solar photovoltaic (PV) technology is a critical component of the UK’s strategy to achieve net-zero emissions by 2050. This report has provided a comprehensive overview of the evolving landscape of PV technology, focusing on its implications for UK housing and grid integration. Crystalline silicon solar cells continue to dominate the market, but thin-film and perovskite solar cells offer promising alternatives. Building-integrated photovoltaics (BIPV) can contribute to energy-neutral buildings, while grid integration challenges can be addressed through energy storage, demand response, and smart grids. Establishing a domestic solar panel manufacturing industry in the UK would enhance supply chain security and foster innovation. Future trends and innovations, such as tandem solar cells, bifacial modules, and advanced materials, have the potential to further reduce the cost of solar energy and improve its efficiency. The context of the ‘Sunshine Bill’ underlines the importance of considering a broad range of technologies and approaches. The rejection of the bill suggests that a more nuanced and comprehensive approach to solar energy policy is needed. While the technologies discussed could have contributed to the bill’s objectives, their successful implementation requires careful consideration of economic, environmental, and social factors. By investing in research and development, supporting domestic manufacturing, and implementing effective policy frameworks, the UK can unlock the full potential of solar energy and contribute to a sustainable energy future.

Many thanks to our sponsor Focus 360 Energy who helped us prepare this research report.

References

• Green, M. A., Emery, K., Hishikawa, Y., Warta, W., & Dunlop, E. D. (2016). Solar cell efficiency tables (Version 48). Progress in Photovoltaics: Research and Applications, 24(7), 905-913.
• Poortmans, J., & Arkhipov, V. (2006). Thin film solar cells: fabrication, physics and applications. John Wiley & Sons.
• Snaith, H. J. (2013). Perovskites: the emergence of a new era for low-cost, high-efficiency solar cells. The Journal of Physical Chemistry Letters, 4(21), 3623-3630.
• Jäger-Waldau, A. (2017). PV status report 2017. Publications Office of the European Union.
• IEA. (2021). Solar PV Global Supply Chains. IEA, Paris
• Fraunhofer ISE. (2023). Photovoltaics Report. https://www.ise.fraunhofer.de/content/dam/ise/de/documents/publications/studies/photovoltaics-report.pdf
• BEIS (Department for Business, Energy & Industrial Strategy). (2021). UK Net Zero Strategy: Build Back Greener. https://www.gov.uk/government/publications/net-zero-strategy
• PV-Tech. (Various Dates). Industry news and analysis on solar PV technology and markets. https://www.pv-tech.org/
• Dhar, P., Hossain, F. M., & Islam, M. M. (2022). Recent advancements and challenges of perovskite solar cells: A comprehensive review. Energy Conversion and Management, 271, 116262.
• Shah, V. M., & Shah, J. J. (2019). Building integrated photovoltaic (BIPV) systems: A review. Renewable and Sustainable Energy Reviews, 107, 568-581.
• O’Flynn, D., Markey, L., & Gallachóir, B. P. Ó. (2018). Potential for demand response to support large-scale wind and solar integration in Ireland. Energy, 163, 387-400.