Prospect of the high efficiency for the VEST (via-hole etching for the separation of thin films) cell

The optimum design of the via-holes for the "VEST cell" (polycrystalline Si solar cell) was studied. Using a simple model, fill factors of the VEST cell were calculated. As for the via-hole distribution pattern, a square grid pattern was found to be most suitable from the view points of the cell performance and the ease of electrode design. It was found that a fill factor large enough (>0.79) for high efficiency can be obtained. A fabricated test cell showed the efficiency of 14.4%. Further Improvement (efficiency over 18%) is possibly expected.