A photoelectric conversion efficiency of over 10% has been achieved in thin-film microcrystalline silicon solar cells which consist of a 2mum thick layer of polycrystalline silicon. It was found that an adequate current can be extracted even from a thin film due to the very effective light trapping effect of silicon with a low absorption coefficient. As a result, this technology may eventually lead to the development of low-cost solar cells. Also, an initial aperture efficiency as high as 13.5% has been achieved with a large area (91 cm x 45 cm) tandem solar cell module of microcrystalline silicon and amorphous silicon (thin film Si hybrid solar cell). An even greater initial efficiency of 14.7% has been achieved in devices with a small size (area of 1 cm(2)), and further increases of efficiency can be expected. (C) 2004 Elsevier Ltd. All rights reserved.