Development of a novel series interconnect for thin-film photovoltaics

Abstract

Thin-film photovoltaics (TF-PV) offer possible cost savings from reduced semiconductor usage compared to the incumbent crystalline silicon technology. During manufacture TF-PV devices are deposited onto a large glass panel and split into many, series interconnected, cells in order to obtain a useful electrical output. M-Solv has patented a novel process to do this series interconnection in a single step, One Step Interconnect (OSI), after the deposition of all layers. This has a number of benefits compared to the conventional process including, but not limited to, reduced capital cost by ~30%, reduced panel transit time and reduced energy usage. In this thesis OSI is introduced, the individual processes developed (laser scribing, inkjet printing of insulator and conductor) and working modules manufactured. The electrical performance of the manufactured modules compare favourably with reference material from the same deposition run and modules interconnected in the conventional way. Fill factor (FF) is the principle metric when determining the quality of series interconnection and very high FF, ~80%, have been shown by OSI cells. Preliminary lifetime testing guided by the IEC 61646 specification has been carried out and the results are promising with OSI cells surviving more than double the required number of thermal cycles from -40 to +85°C with no sign of performance degradation.