Developmental experiments on large‐area silicon solar cells

摘要

A comprehensive design/material/technological study was conducted with the aim of obtaining high‐efficiency back‐surface‐field‐ (BSF‐) type bifacial solar cells withreproducibleparameters onlarge‐arean‐ andp‐silicon wafers. Practical ways of attenuating the severe limitations imposed by different kinds of areal inhomogeneities on the electro‐optical performance of large‐area BSF single‐crystal silicon solar cells are described and tested experimentally. Various procedures leading to a substantial increase of both the emitter and the base contributions to the generated photocurrent are implemented and discussed in detail. Thep+‐n‐n+andn+‐p‐p+cells were processed as bifacial devices and tested under both front and backside AM1 illumination. The trial devices were fabricated on 2‐in and 3‐in. commercially available lower‐grade silicon and the minimization of the cell cost was one of the sought‐after objectives. The combination of simple design/technological approaches described in this work has ultimately led to the development oflow‐cost,high‐efficiency(17–18) large‐area silicon solar cells with good overall electro‐optical performance as bifacial devices. The results of this work show clearly that simple, but adequately designed/processed cells fabricated on an industrial scale on large‐area silicon wafers could possess parameters similar to those of sophisticated laboratory samples elaborated on small‐area silicon. With the design/technological approaches outlined in this work, the use of even cheaper, i.e., lower‐grade single‐crystal silicon, could still yield 2‐ and 3‐in. cells with fairly acceptable conversion efficiencies.