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Solar Power Grows 400 Percent in Only 4 Years by Daniel Cusick Scientific American, April 24, 2014

More than half of the added capacity comes from home and business owners

Driven by an explosion in photovoltaics, the U.S. solar sector has emerged "from a relatively small contributor to the nation's total electric capacity into a one of comparative significance," the Energy Information Administration reported this week in its latest Electricity Monthly Update.

Since 2010, EIA said, U.S. solar capacity increased 418 percent from 2,326 megawatts, accounting for 0.2 percent of total U.S. electric generation, to today's 12,057 MW, or 1.13 percent of U.S. generation.

More than half of that additional capacity -- 5,251 MW -- has been installed by home and business owners participating in utility net metering programs that allow owners of solar systems to sell excess capacity back to their local utility at retail rates, according to EIA.

California has the largest net metered solar capacity, with 38 percent of the U.S. total, but Eastern states such as Massachusetts and New Jersey also have significant amounts of net metered solar energy, the agency said.

Utility-scale PV applications, defined as systems with 1 MW or more of capacity, have also expanded significantly and currently account for 5,564 MW, according to EIA. Such systems generally are designed to generate power for wholesale markets.

California accounts for roughly half of all U.S. installed utility-scale PV solar with more than 2,700 MW of capacity, followed by Arizona with 960 MW (17 percent) and North Carolina with 340 MW (6 percent), according to EIA.

While accounting for only a handful of total U.S. solar installations, the development of utility-scale solar thermal systems that concentrate the sun's energy to drive a traditional turbine using very high temperatures have also seen significant growth in recent years.

Just since last year, nearly 700 MW of new solar thermal capacity came online with the completion of three large power plants in the Southwest. These include the 280 MW Solana Generating Station near Gila Bend, Ariz.; the 125 MW Phase 1 of the Genesis Solar Energy Center near Blythe, Calif.; and the 377 MW Ivanpah Solar Electric Generating Station in California's Mojave Desert.

And according to EIA, each of the three solar sectors enjoys "strong near-term growth prospects." As of this month, there are 6,459 MW of proposed utility-scale PV installations in the development or planning stages and 1,841 MW of proposed thermal solar plants, the agency said.