|Solar photovoltaic panels line the roof of the visitor center at the Parker River National Wildlife Refuge in Massachusetts.|
The solar energy projects placed in service last month vary widely in scale and in technology. The largest, Abengoa SA's Solana Generating Station in Arizona, generates up to 280 megawatts of power using a thermal concentrating solar power technology. 2,700 parabolic trough mirrors focus the sun's rays on a pipe containing a synthetic oil. This heat transfer fluid can reach 735 degrees Fahrenheit, and is sent to boilers where it produces steam from water. The steam turns turbines attached to generators, much as in a conventional thermal power plant. The Solana plant also features energy storage in the form of molten salt tanks that can enable it to generate electricity for up to 6 hours after sunset.
On the other end of the spectrum, Constellation Solar New York LLC placed its 2 MW Owens Corning Delmar Solar photovoltaic project online. The project, located at an Owens Corning factory in Delmar, New York, consists of about 9,000 ground-mounted, photovoltaic panels covering over 9 acres. Power produced by the project is sold to Owens Corning under a long-term power purchase agreement for use at the thermal and acoustical insulation factory; the project is expected to cover about 6 percent of the plant's annual electricity need.
While the use of solar energy is increasing rapidly, it remains a relatively small component of the nation's overall energy mix. Solar powered projects account for 6.79 gigawatts of capacity, just 0.59% of the 1,158 gigawatts of existing electric generation capacity nationwide. Nevertheless, the relatively small market penetration of solar technologies suggests that rapid growth may continue for the near term.