Micro solar concentrators: Design and fabrication for microcells arrays

In this work we look at a micro-concentrating system adapted to a new type of solar concentrator photovoltaic material, well known for flate-plate applications, Cu(In,Ga)Se₂. Cu(In,Ga)Se₂ solar cells are polycrystalline thin film devices that can be deposited by a variety of techniques. We proposed to use a microcell architecture [1], [2], with lateral dimensions varying from a few μm to hundreds of μm, to adapt the film cell to concentration conditions. A 5% absolute efficiency increase on Cu(In,Ga)Se₂ microcells at 475 suns has been observed for a final efficiency of 21.3% [3]. We study micro-concentrating systems adapted to the low and middle concentration range ([4], [5]), where thin film concentrator cells will lead to substrate fabrication simplification and costs savings. Our study includes optical design, fabrication and experimental tests of prototypes.