SCIENCE: Breakthrough close on solar power

The start of mass production of solar cells made with silicon could be the beginnings of truly commercial cost-effective solar power, according to an American expert.

The efforts of three companies in the US and Japan to make "amorphous silicon" solar cells this year for use on houses means that the industry is close to breaking through the cost-efficiency barrier, says Christopher Wronksi, a professor of microelectronic materials and devices at Penn State University. "The next four or five years could determine the future of this industry," he said.

Amorphous silicon solar cells consist of a conducting layer with three very thin films of silicon-based material, in which the middle layer is electrically neutral and the outer two have opposite electrical properties. When the sun's rays hit the layers, the energy of the light moves electrons between them, generating electricity. However, the efficiency - the ratio of incident energy in the light compared to electrical output - is between 10 and 14 per cent in industrial products.