Conventional photovoltaic panels require very pure silicon, which is therefore expensive, which makes the electricity produced little competitive.
The most promising alternative uses copper-indium-gallium diselenide (DSCIG), 350 times more efficient than silicon at absorbing incident solar energy. However, despite twenty years of research no commercial panel could be achieved.
Vivian Alberts and her team (Rand Afrikaans University) have patented a process to manufacture DSCIG panels at low cost (66 EUR for a 50 W panel with a lifespan of 15 to 20 years). A 30 m2 panel would produce the electricity necessary for a family of 4 and the energy required for its manufacture (gross energy content) would be recovered after one to two years of operation. The manufacturing process requires two instruments specially manufactured to Vivian Alberts specifications: a disperser designed by Leybold Optics (Dresden) and a diffusion oven (Wilro Technologies, the Netherlands).

source: http://www.scienceinafrica.co.za