I have been following a company called Nanosolar for sometime. They have developed a method for printing solar cells on aluminium foil. The Solarply technology promises cells at 50p per watt. That's £50 for a 100W panel. Much more affordable than the polycrystalline cells of today, where a 100W panel will set you back £700.
Guardian - Solar energy 'revolution' brings green power closer
Nanosolar - Company website