Solar Research: On the Hunt for the Super-cell

European Sharc25 project aims to achieve 25 percent efficiency with thin-film solar cells

Prime objective of the Sharc25 project is to develop super-high efficiency Cu(In,Ga)Se2 (CIGS) solar cells for next generation of cost-beneficial solar module technology with the world leading expertise establishing the new benchmarks of global excellence.
The project partners ZSW and EMPA hold the current CIGS solar cell efficiency world records of 21.7% on glass and 20.4% on polymer film, achieved by using high (~650°C) and low (~450°C) temperature CIGS deposition, respectively. Both have developed new processing concepts which open new prospects for further breakthroughs leading to paradigm shift for increased performance of solar cells approaching to the practically achievable theoretical limits. In this way the costs for industrial solar module production < 0.35€/Wp and installed systems < 0.60€/Wp can be achieved, along with a reduced Capex < 0.75€/Wp for factories of >100 MW production capacity, with further scopes for cost reductions through production ramp-up.
In this project the performance of single junction CIGS solar cells will be pushed from ~21% towards 25% by a consortium with multidisciplinary expertise. The key limiting factors in state-of-the-art CIGS solar cells are the non-radiative recombination and light absorption losses. Novel concepts will overcome major recombination losses: combinations of increased carrier life time in CIGS with emitter point contacts, engineered grain boundaries for active carrier collection, shift of absorber energy bandgap, and bandgap grading for increased tolerance of potential fluctuations. Innovative approaches will be applied for light management to increase the optical path length in the CIGS absorber and combine novel emitter, front contact, and anti-reflection concepts for higher photon injection into the absorber. Concepts of enhanced cell efficiency will be applied for achieving sub-module efficiencies of >20% and industrial implementation strategies will be proposed for the benefit of European industries.