White back reflector on sputtered zinc oxide back contact for micromorph silicon thin-film solar modules

Silicon-based thin-film photovoltaics is on the way the overcome drawbacks such as high degradation and low efficiencies by applying novel multiple-junction solar cells consisting of amorphous and microcrystalline absorber layers. In order to produce reliable high-power low-cost solar modules the design of the back contact and back reflector is an important issue. In this paper, ersol Thin Film GmbH presents the first results of an alternative concept which combines the production advantages of a sputtered back contact with the optical advantages of a printed dielectric white back reflector. Due to this functional separation, specific requirements on the back contact layer properties need to be fulfilled resulting in a trade-off between optical and electrical power losses while taking into account the cost-of-ownership of the production facility. It will be demonstrated, that the photocurrent can be steadily increased by enhancing the light management resulting in optimum energy conversion efficiency.