Technology Review has an article on concentrating solar PV company Amonix - Concentrated Solar Set to Shine.
Amonix recently launched its newest solar concentrator, which converts one fourth of the sunlight that falls on it into AC electricity. That's compared with the approximately 18 percent system efficiency--including inverters that convert solar's DC power to useable AC power--of the most efficient photovoltaic systems that don't use special optics or track the sun.
To collect sunlight as efficiently as possible, Amonix starts with a massive 23.5-meter-by-15-meter array. The array is covered with thin, plastic Fresnel lenses, each measuring 350 square centimeters, that focus sunlight to an area that's .7 square centimeters. The sunlight, concentrated to 500 times its normal intensity, hits an ultra-efficient multi-junction solar cell that converts 39 percent of the light into electricity. The cell, made by Spectrolab, is the most efficient in the world, demonstrating more than 41 percent efficiency in lab tests. To further enhance performance, Amonix uses a tracking system that keeps the lenses pointed within .8 degrees of the angle of the sun throughout the day.
Utility companies, however, have been reluctant to invest in any concentrated photovoltaic systems due in part to the device's high level of complexity. Proper functioning of each component is crucial because the lenses require very precise alignment with the sun in order to focus light on the solar cells. "The difference between being in alignment and being one degree off is the entire system works or it doesn't," says Johanna Schmidtke, an analyst with Lux Research.
Amonix's technology already accounts for some 13 megawatts of installed capacity, which represents more than half of all installed concentrated photovoltaic capacity in the world. And so long as Amonix can prove its reliability, its technology offers several distinct environmental advantages over other types of utility-scale solar.