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The EU-funded CPVMATCH project set out to bridge the gap between theoretical ultra-high efficiency solar cells and practical applications by targeting performance improvements and cost reductions through innovative designs, materials and manufacturing techniques.
The project focused on a technology called concentrator photovoltaics (CPV) which uses mirrors or lenses to capture sunlight and concentrate it on to miniature multi-junction solar cells; the system is driven by a tracker that follows the sun’s path during the day. These CPV cells use different materials stacked on top of each other to capture more of the light spectrum more efficiently than conventional photovoltaics.
One four-junction module tested in the project was able to convert 41.4 % of direct solar irradiation into electricity – the highest value ever measured for a photovoltaic module and about twice the efficiency of conventional modules.
‘The module clearly demonstrates the potential of CPV, and paves the way for further improvements,’ says project manager Gerald Siefer of the Fraunhofer Institute for Solar Energy Systems in Germany. ‘On the cell side, we have successfully demonstrated designs for cells using alternative materials, and we are sure that in the short term we could bring efficiency to 45 % or more.’
Although cost and material challenges mean full-scale commercial production of modules with above 40 % efficiency remains some way off, the CPVMATCH partners are already deploying techniques and technologies developed in the project across a number of photovoltaic products, including achromatic lenses and mirror optics.
Among several key innovations, the CPVMATCH partners developed efficient methods for producing cells with four junctions. They also improved the design of the module which contains the cell and the concentrating optics – a key factor in reducing manufacturing costs and minimising resource use and the carbon footprint of solar-panel production.
‘In CPVMATCH, we have addressed all production steps for concentrator modules, starting from the materials, through cell fabrication and production systems, and up to the challenges facing module manufacturing,’ Siefer concludes.