Mr Sethi believes his product will cut the cost to 80 cents per watt within five years, and 50 cents in a decade.
It is based on a CIGS (CuInGaSe2) semiconductor compound that absorbs light by freeing electrons. This is then embedded on the polymer base. It will be ready commercially in late 2009.
"It’ll even work on a cold, grey, cloudy day in England, which still produces 25pc to 30pc of the optimal light level. That is enough, if you cover half the roof," he said.
"We don’t need subsidies, we just need governments to get out of the way and do no harm. They’ve spent $170bn subsidising nuclear power over the last thirty years," he said.
His ultra-light technology, based on a copper indium compound, can power mobile phones and laptop computers with a sliver of foil.
"You won’t have to get down on your knees ever again to hunt for plug socket," he said
Michael Rogol, a solar expert at Credit Lyonnais, expects the solar industry to grow from $7bn in 2004 to nearer $40bn by 2010, with operating earnings of $3bn.
The sector is poised to outstrip wind power. It is a remarkable boom for a technology long dismissed by experts as hopelessly unviable.
Mr Rogol said he was struck by the way solar use had increased dramatically in Japan and above all Germany, where Berlin’s green energy law passed in 2004 forces the grid to buy surplus electricity from households at a fat premium. (In Britain, utilities may refuse to buy the surplus. They typically pay half the customer price of electricity.)
The change in Germany’s law catapulted the share price of the German flagship company SolarWorld from €1.38 (67p) in February 2004 to over €60 by early 2006.
The tipping point in Germany and Japan came once households twigged that they could undercut their unloved utilities. Credit Lyonnais believes the rest of the world will soon join the stampede.
Mike Splinter, chief executive of the US semiconductor group Applied Materials, told me his company is two years away from a solar product that reaches the magic level of $1 a watt.
Cell conversion efficiency and economies of scale are galloping ahead so fast that the cost will be down to 70 US cents by 2010, with a target of 30 or 40 cents in a decade.
"We think solar power can provide 20pc of all the incremental energy needed worldwide by 2040," he said.
"This is a very powerful technology and we’re seeing dramatic improvements all the time. It can be used across the entire range from small houses to big buildings and power plants," he said.
"The beauty of this is that you can use it in rural areas of India without having to lay down power lines or truck in fuel."
Villages across Asia and Africa that have never seen electricity may soon leapfrog directly into the solar age, replicating the jump to mobile phones seen in countries that never had a network of fixed lines. As a by-product, India’s rural poor will stop blanketing the subcontinent with soot from tens of millions of open stoves.
Applied Materials is betting on both of the two rival solar technologies: thin film panels best used where there is plenty of room and the traditional crystalline (c-Si) wafer-based cells, which are not as cheap but produce a higher yield – better for tight spaces.
Needless to say, electricity utilities are watching the solar revolution with horror. Companies in Japan and Germany have already seen an erosion of profits because of an effect known "peak shaving". In essence, the peak wattage of solar cells overlaps with hours of peak demand and peak prices for electricity in the middle of the day, crunching margins.
As for the oil companies, they are still treating solar power as a fringe curiosity. "There is no silver bullet," said Jeroen Van der Veer, Shell’s chief executive.
"We have invested a bit in all forms of renewable energy ourselves and maybe we’ll find a winner one day. But the reality is that in twenty years time we’ll still be using more oil than now," he said.
Might he be wrong?
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