The New York Times

The number of solar installations grew strongly in the nation’s residential, commercial and utility sectors in the third quarter, largely as a result of falling costs, a federal investment tax credit and state programs that support renewable energies, the solar industry’s main trade group reported on Tuesday.

The Solar Energy Industries Association said that 684 megawatts of solar photovoltaic capacity was installed in the quarter, 44 percent more than in the third quarter of 2011. For the first three quarters of the year, the industry added 1,992 megawatts, compared with 885 megawatts for all of 2011.

The latest increase brings installed photovoltaic capacity to 5.9 gigawatts. When combined with concentrated solar power installations, which involves focusing solar energy on a single point to begin a heating process that will turn turbines, the figure rises to 6.4 gigawatts, or enough to power around one million average American homes, the organization said.