Installations also rose 45% from 512MW in the first quarter. First half installations were 1.254GW, more than double 622.7MW a year earlier.

“More solar was installed in the U.S. this quarter than in all of 2009, led for the first time by record-setting utility-scale projects. With costs continuing to come down, solar is affordable today for more homes, businesses, utilities, and the military,” says SEIA chief executive Rhone Resch.

The US on 30 June had 5.7GW of installed solar capacity including 5.161GW of PV and 546MW of concentrating solar power (CSP), enough to provide electricity for more than 940,000 homes, according to GTM, a consulting company. The industry employs 100,000 Americans.

It forecasts that 3.2GW may be installed in the US this year, down slightly from the 3.2GW estimate in the first quarter, up 71% from 2011. This will push US share of global installations to more than 10% from 7% in 2011 and less than 5% in 2010.

California led total second quarter PV installations with 217MW versus 150MW in the first quarter, followed by Arizona with 173MW against 63MW, and New Jersey 103MW down from 174MW.

Eight states posted utility-scale installations of 10MW or greater: California, Arizona, Nevada, Texas, Illinois, North Carolina, New Mexico, and New Jersey. By the end of this year, the utility market will account for 54% of total installations. Residential installations grew slightly in the second quarter to 98.2MW from a year earlier, while those for non-residential declined to 196.3MW.

“The non-residential market has struggled where incentive levels or SREC prices decline, implying system costs must fall further before state incentives become unnecessary, the SEIA/GTM report says.

It notes that system prices continue to fall, bringing the market ever closer to the point where residential and non-residential demand is driven more by solar radiation and retail electricity prices than state-level incentives.

The average price for a residential system in the second quarter was $32,453 against $37,144 a year earlier. For all installed solar quarter-over-quarter, the national weighted-average system price fell 22%, from $4.44/watt to $3.45/watt, the report says. Year-over-year, average installed costs declined 33%. It notes these gains were heavily influenced by the volume of utility-scale installations. Cogentrix’s 30MW CPV plant also came online during the second quarter.

Looking ahead, SEA/GTM forecasts that 2013 US installations will increase 21% from this year, with average annual growth between 25% and 30% in the 2012-2016 period.