Interconnector-based module technology for thin MWT cells

In this work we advance the concept of ribbon interconnection to meet two challenges for PV module technology: thin cells with a thickness of around 100mm and back contact solar cells with distributed contacts on the rear cell side. Both aspects require an adaptation of the traditional module concept because simply soldering conventional ribbons to the cells' rear side leads to high thermomechanical stress and thus excessive cell bow after soldering. This fact becomes even more critical when the cells are thin. The proposed concept uses structured interconnectors that avoid cell bow after interconnection but still exhibit adequate electrical conductivity. To isolate parts of the interconnector from the opposite polarity on the rear cell side a non-woven fabric is used. The applicability of this concept for high conversion efficiencies and for low cell-to-module losses is demonstrated by small scale MWT-modules containing 16 (4 × 4) resp. 10 (5 × 2) cells. Fill factors above 77 %, module efficiencies of up to 17.0 % (ap) and cell-to-module losses of 1.0 %abs are measured. The reliability of the concept is tested by temperature cycling resulting in no measurable degradation of the IV-parameters and in no visible deterioration of the EL images.