Process development of high performance CIGS modules for mass production

The technology of Cu(In,Ga)Se2 (CIGS)-based solar modules is close to commercialisation. However, the high cost-reduction potential can only be realised with mass production. ZSW has developed all process steps for a 30 cm×30 cm CIGS line. Very high performance CIGS modules with an efficiency close to 13% and smaller mini-modules close to 15% were prepared with this line. Critical process steps like in-line one-step co-evaporation were assessed and further scaled up. Several hundred modules with different sizes were produced and statistical data about process parameters were evaluated. The share of material costs is discussed in comparison to other cost categories. The reliability of the modules was investigated with accelerated lifetime tests. Corrosion of the molybdenum contact and the degradation of zinc oxide were found to be the dominating effects for the deterioration of raw modules in the damp heat test. The process know-how of ZSW is transferred to the company Wurth Solar GmbH & Co.KG, a joint venture of ZSW GmbH, Wurth group, and EnBW AG. At Wurth Solar all process steps for 120 cm×60 cm CIGS modules are now built up and have started operation.