Series-connection of thin-film crystalline Si solar modules with a single metallisation step

Abstract

A novel module interconnection scheme for silicon thin-film cells from layer transfer processes is introduced. All metallization is applied in a single processing step. The resulting thin-film modules are bifacial. No losses due to shading occur under illumination from the non-metallized and non-diffused side. Light falling on the area between neighboring cells is partially used if a diffuse reflector is included. The main technological advantage of the interconnection scheme is, however, the reduced number of process steps. First modules (25.5 cm2) demonstrate efficiencies up to 12.2 % under 1 sun illumination through the diffused and contacted side. Series resistance losses in the emitter reduce the fill factor and thus prevented the demonstration of even higher efficiencies. Thermographic investigation reveal that plasma etching of the metallized module may lead to shunting if the metal fingers become to hot during the etching procedure.