A SIMPLE ANALYSIS OF BURIED CONTACT SILICON SOLAR-CELLS

One of the most promising structures for solar cells is the buried con tact solar cell (BCSC), because it offers the possibility of productio n at low cost, at the same time that allows the combination of several high efficiency concepts, without any design compromise as occurs in conventional cells. Therefore, there is a growing interest for such ki nd of solar cells. Unfortunately, this structure poses new problems fo r its design since the buried contact will cause 2-dimensional carrier flow effects under both light and dark current conditions. However, a s we describe in this paper, it is possible to make a simple analysis of the conversion efficiency as a function of the buried contact depth in the BCSC cell. In this article we show that the efficiency is mini mum for depths in the range between 50 mu m and 70 mu m when the assum ed parameters are typical for silicon solar cells. In addition, we sho w that in order to have good performance for these cells, the buried c ontact depth should be either very small (below 5 mu m), or very large (bigger than 150 mu m), but not in-between these values, in order to avoid any efficiency degradation caused by the buried contacts. Finall y, we show that the efficiency can be better than for conventional cel ls only when the buried contacts have a large depth, whenever they are designed properly in such a way that they allow an additional collect ion of charge carriers generated by sunlight.