Development of large-area monolithically integrated silicon-film photovoltaic modules

Abstract

This report describes work to develop Silicon-Film Product III into a low-cost, stable device for large-scale terrestrial power applications. The Product III structure is a thin (< 100 {mu}m) polycrystalline silicon layer on a non-conductive supporting ceramic substrate. The presence of the substrate allows cells to be isolated and in interconnected monolithically in various series/parallel configurations. The long-term goal for the product is efficiencies over 18% on areas greater than 1200 cm{sup 2}. The high efficiency is made possible through the benefits of using polycrystalline thin silicon incorporated into a light-trapping structure with a passivated back surface. Short-term goals focused on the development of large-area ceramics, a monolithic interconnection process, and 100 cm{sup 2} solar cells. Critical elements of the monolithically integrated device were developed, and an insulating ceramic substrate was developed and tested. A monolithic interconnection process was developed that will isolate and interconnect individual cells on the ceramic surface. Production-based, low-cost process steps were used, and the process was verified using free-standing silicon wafers to achieve an open-circuit voltage (V{sub oc}) of 8.25 V over a 17-element string. The overall efficiency of the silicon-film materials was limited to 6% by impurities. Improved processing and feedstock materials are undermore » investigation. « less

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