U.S. Government Backs Concentrated Photovoltaics

Big solar: Massive solar panels like the 24-meter-wide ones shown here will be installed at a 30-megawatt solar farm being supported by the U.S. Department of Energy.
Credit: Amonix

Energy

A 30-megawatt plant will be one of the largest to use the technology.

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.
The project is part of a surge in photovoltaic projects in the United States over the last few years. A total of 878 megawatts' worth of solar panels were installed last year, up from just 79 megawatts in 2005. This year total installation is expected to double 2010 levels, according to the Solar Energy Industries Association. The industry is starting to approach the scale of the wind industry, which saw over 5,000 megawatts of capacity installed last year (down from over 10,000 the year before).
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.