Flexible solar cells and modules

Abstract

Flexible photovoltaic (PV) modules enable a wealth of applications in architecture, clothing integration, or other mobile power supplies. Moreover, a simple and cost-effective roll-to-roll manufacturing of thin film PV modules could in the long run compete with large area glass plate processing for the PV power market. Based upon the optimisation of amorphous, nano and protocrystalline silicon thin films, flexible solar cells grown at temperatures between 40°C and 110°C are described with power conversion efficiency up to 5%. A novel in situ series connection technique establishes monolithic integration of such cells into a PV module by locally masking thin film deposition, without any laser patterning or breaking of the continuous production flow. The first flexible modules from a non-optimised, single junction n-i-p structure demonstrate the function of the in situ series connection, and exhibit a total area efficiency of 3%, resulting from an average single cell efficiency of 3.3% and a total interconnection loss of only 15% over the 40 cm2 module area.