Copper Indium Gallium Selenide (CIGS) Thin-Film Solar Cells
Copper indium gallium selenide (CIGS) is a semiconductor material composed of copper, indium, gallium, and selenium elements. It is used to manufacture thin-film solar panels which are lightweight and flexible alternatives to traditional crystalline silicon solar panels.
Overview
CIGS thin-film PV utilizes a thin layer of CIGS material deposited onto a supporting substrate like glass, metal or plastic to absorb sunlight and convert it into electricity.
CIGS solar cells offer lab efficiency ratings as high as 22.9%, higher than other thin-film technologies. Commercial CIGS modules typically achieve 15% to 18% efficiency. This is lower than silicon panels but the technology offers other advantages.
CIGS is a direct bandgap semiconductor ideal for photovoltaic conversion. It absorbs sunlight strongly allowing the use of thin absorber layers. The ratio of indium to gallium can be varied to tune the bandgap.
However, limited global indium supplies and complex vacuum deposition manufacturing techniques have inhibited mainstream CIGS adoption so far. The technology shows great promise but production cost and scale challenges remain.
Benefits of CIGS Solar Panels
High Efficiency for Thin-Film PV With lab cell efficiency exceeding 20% and commercial modules in the 15-18% range, CIGS is the most efficient thin-film PV technology today. This narrows the gap with conventional silicon panels. Higher efficiency means more power output per unit area.
Low Light Performance CIGS maintains higher efficiency than silicon under diffuse, cloudy or low light conditions. This gives CIGS an advantage in the frequently overcast climate of the UK.
Temperature Resilience Electrical output of CIGS panels declines less than silicon as temperatures increase. Hot summer performance is enhanced.
Lightweight and Flexible CIGS cells can be deposited onto flexible plastic or metal foil substrates. This enables lightweight, bendable solar structures not possible with rigid silicon panels.
Customizable Aesthetics Varying the ratio of indium to gallium changes the CIGS layer color. Combined with flexible substrates, this allows customized colors and semi-transparent panels.
Drawbacks and Challenges Facing CIGS
Complex Vacuum Manufacturing Specialized high-vacuum techniques like co-evaporation or sputtering are needed to deposit the CIGS absorber. This requires heavy capital investment and precise process control, increasing production costs.
Low Manufacturing Scale Complex CIGS production has inhibited ramping up global manufacturing capacity, limiting economies of scale. Total production remains low compared to other PV technologies.
Indium Supply Constraints Indium is a rare element and supplies are tight. Expanding CIGS adoption could face indium shortage risks, causing price volatility. However, low concentrations of indium are needed in each cell.
Efficiency Drops Over Time CIGS panels can experience thermal degradation, losing a few percent of initial performance over the first years of operation. But overall lifetime remains comparable to silicon PVs.
Considerations for CIGS Solar in the UK When evaluating CIGS, UK solar buyers should consider:
- Performance benefits under diffuse light and cloudy conditions
- Flexible panel options for bespoke building integration
- Higher cost vs silicon PVs currently until manufacturing scales up
- Technical expertise required for optimal system design and installation
The Outlook for CIGS PV in Britain With its lightweight flexibility and efficiency advantages in low-light conditions, CIGS thin-film PV shows strong potential for greater adoption in the UK for both residential and commercial solar projects. The technology delivers performance tailored to Britain’s climate. As manufacturing processes and supply chains mature, CIGS looks set to claim a key role in the UK’s growing solar energy future.
