Photovoltaic electricity capacity in the U.S. will nearly triple this year to 2.4 gigawatts according to a forecast from research firm IHS iSuppli.

Still, solar will continue to sit under the long, long shadow of other energy sources like fossil fuels and nuclear. While the 2.4 GW represents an impressive 166% gain over what IHS says was 900 GW installed in 2010, it’s less than 1% of the U.S. electricity total.

For some perspective, in 2010, the U.S generated about 4,120 billion kilowatthours (4,100 gigawatthours) of electricity according to the Energy Information Administration, about 70% of which came from fossil fuels - some 45% from coal – and 20% from nuclear.

The solar percentage looks slightly better, although still fractional, when compared with new capacity. According to information released yesterday by the EIA, the U.S. added 11.25 GW of capacity in the first six months of this year.

Comparing the IHS numbers with the EIA statistics (sorry for the apples and oranges, but the mixed fruit pie chart in this case does at least give a representative flavor of the story), the 11.25 GW of overall new capacity for half a year is 7.5 times the 1.5 GW of new solar for the entire year.

“From January to June 2011, 162 electric power generators were added in 36 states, for a total of 11,255 megawatts (MW) of new capacity,” EIA reported. "Of the ten states with the highest levels of capacity additions, most of the new capacity uses natural gas, coal, or wind.”

If you assume that overall capacity will grow by the same amount in the second half- admittedly a fluffy assumption – then PV is about 6% of the new stuff. That’s starting to sound a little better than the “less than one percent” space to which solar has been relegated in overall contribution to U.S. electricity. It also gets it closer to the more respectable 1% ascribed to solar’s renewable rival, wind.

The IHS forecast does not include electricity generated from solar thermal plants.

IHS said the 1.5 GW rise in solar PV capacity comes largely from the installation of utility scale plants, and that California is leading all states this year in new PV “by a wide margin” with 967 megawatts, followed by New Jersey with 263 MW, Arizona with 243 MW, New Mexico with 139 MW and Nevada with 118 MW.

“The number of U.S. PV installations this year is projected to climb to approximately 49,000—up from 39,000 in 2010,” IHS said in a press release. “Of the 2.4GW in solar power expected to be installed this year, ground installations will contribute approximately 1.4GW, commercial installations 710 megawatts (MW) and residential installations 270MW.”

It attributed the increase in part to loan guarantees provided by the U.S. Department of Energy, which it says will support continued growth while Europe PV slumps. IHS predicted that U.S. PV capacity will hit 3.1 GW next year, and 5.5 GW by 2015.

Photo: BP

This post was originally published on Smartplanet.com