The Zebra Cell Concept - Large Area n-Type Interdigitated Back Contact Solar Cells and One-Cell Modules Fabricated Using Standard Industrial Processing Equipment

In this paper we present relevant characteristics of our Zebra cells and one-cell modules. The Zebra cell is an interdigitated back contact (IBC) solar cell produced at ISC Konstanz using only industrially proven technologies and standard industrial size 156x156mm2 n-type Cz wafers. Wafers of different suppliers have been evaluated. The best efficiencies achieved so far on a batch of 21 wafers are 21% average (champion cell: 21.3%). Reverse bias electroluminescence (ReBEL) measurements reveal the unique breakdown behavior of the Zebra cell. Due to its alternating pn regions on the rear, a homogenous breakdown along the parallel junctions is observed which does not lead to local shunting. The Zebra cell can be stringed using standard soldering or bonding with conductive adhesives. Cell to module losses are comparable to standard p-type Al BSF cells. Due to its open rear side structure, the Zebra cell is bifacial. When testing one-cell modules with transparent and black backsheet outdoors our measurements show an average rise in power output of 13% relative for the bifacial module compared to its monofacial reference.