A relatively new type of solar power called concentrated photovoltaic (CPV) technology is getting a $90.6 million boost in the form of a conditional loan guarantee from the U.S. Department of Energy. The government backing will help with financing for a 30-megawatt facility near Alamosa, Colorado, which will be one of the largest concentrated-photovoltaics plants ever built.
Concentrated photovoltaics is different from concentrated solar power, which is also known as solar thermal. In solar thermal plants, mirrors and lenses concentrate sunlight to generate the temperatures needed to produce steam that drives a turbine and generator.
In CPV, arrays of lenses are used to focus sunlight onto small solar cells. The concentrated light improves the efficiency of the cells and reduces the amount of expensive solar cell material needed to produce a given amount of electricity. Amonix, the company that will be supplying the concentrated photovoltaic systems for the project, says its system can generate twice as much power per acre as conventional solar panel technology. It uses 23.5-meter-wide panels with more than 1,000 pairs of lenses and solar cells on each. The panels are mounted on tracking systems that keep the lenses pointed within 0.8 degrees of the angle of the sun throughout the day, to ensure that light falls on the system's 0.7-square-centimeter solar cells.
CPV accounts for a small part of the solar market now—just 0.1 percent. That's largely because it's newer than ordinary photovoltaic technology and has been more expensive; it's more complex, since the lenses have to precisely track the sun. Lowering the cost of CPV will require scaling up. The biggest CPV plants built so far have been in the range of one or two megawatts, while the largest flat-panel plants are 85 and 92 megawatts.
Some analysts expect the CPV market to more than double every year through 2015 as more companies scale up production. At least one other company, Soitec, is planning a 200-megawatt CPV plant in the next few years.
