If, on the one hand, you've got biofuels which represent only a half a percent conversion of sunlight, and let's say you've got photovoltaic cells and concentrated solar power systems, the efficiency of solar in terms of pure conversion is 50-100 times greater.

CNN: Biofuels: What do the experts think?

And the Energy Conversion exec adds that the company is working on new technology that should improve the conversion efficiency of its thin-film solar products.

FORBES: Energy Conversion Devices Responds To Debt Concerns

In the lab Cigs has a maximum solar conversion efficiency of 20.2%, better than the 16.5% of a thin-film technology that kicks the pants off the traditional crystalline silicon panels on price per watt of capacity.

FORBES: Energy & Genius

This high efficiency PV technology allows Suntech to achieve conversion efficiency rates in the range of 18% to 19% on PV cells manufactured with monocrystalline silicon wafers and 16.5% to 17.5% on PV cells manufactured with multicrystalline silicon wafers.

FORBES: Suntech Power Stock Shines With 25% Upside

Speaking of solar efficiency, this week solar manufacturer Amonix announced that its concentrated photovoltaic technology has set a new efficiency record with a conversion rate of 33.5 percent.

ENGADGET: Inhabitat's Week in Green: Dyson Spheres, bladeless wind turbines and airless bike tires