Cheapening the sun

A Silicon Valley-based company says it’s found a way to make solar power cheaper than coal. Its solution to the huge problem of making renewable energy an affordable option for the masses is tiny—something so small it can slip through the skin.

The PowerSheet, created by Nanosolar, earned Popular Science’s 2007 “Innovation of the Year” award for making solar energy a viable, mainstream energy option. It’s a metal sheet as thin as aluminum foil and coated with solar-absorbing nano-ink.

The key is the itty bitty “nano.” A human hair, for instance, is about 80,000 nanometers wide. The use of nano-ink is much more cost-efficient than silicon, the conventional solar power material. Nanosolar says it can make panels at a tenth of what current panels cost, reducing it from about $3 per watt to 30 cents per watt. (To compete with coal, energy costs need to be $1 per watt or less.)

At its factory in San Jose, Nanosolar plans to produce the sheets like a printing press, and it expects to roll out 430 megawatts-worth of solar cells a year.