ZEBRA technology: low cost bifacial IBC solar cells in mass production with efficiency exceeding 23.5%

The ZEBRA technology - since several years under development at ISC Konstanz - is a bifacial IBC solar cell concept based on a standard industrial low cost manufacturing process still without passivating contacts. In this work, we present results of the industrial implementation of the ZEBRA cell technology in a 200 MW p /year production line in Xining (China) in a collaboration between HHSD/SPIC Xi'an Solar Power and ISC Konstanz. In particular, we report on processes for this advanced bifacial IBC technology and on first results achieved in industrial production at SPIC. At the current stage of ramp-up of the industrial cell line, average energy conversion efficiencies of 23.6% and open circuit voltages above 700 mV have been achieved. These values are reached using a simple cell process, based on standard LP-BBr 3 - and POCl 3 -tube furnace diffusion steps and on a screen printing metallization process that is compatible with any commercial format (e.g. also M6, M8 and M12) of n-type Cz-Si wafers. Modules have been fabricated in SPIC's industrial manufacturing line by soldering of ribbons on half-cut ZEBRA-cells. Thereby a P mpp of around 360 W p has been achieved using a module design based on 120 G1 half-cells corresponding to an efficiency of around 21.2%.