In 2011 the U.S. solar industry installed a total of 1,855 megawatts or 1.9 gigawatts (GWs) of photovoltaics, compared to 887 MWs in 2010. That represents a 109 percent year-over-year growth rate, according to the U.S. Solar Market Insight: Year-in-Review 2011 report from GTM Research and the Solar Energy Industries Association (SEIA).

The report also suggested that this year even more solar will come online, including some of the first new concentrating solar power projects. It’s the latest sign that the industry is continuing to strengthen.

“Far and away the best year for solar installations in a single year,” said SEIA President Rhone Resch during a teleconference announcing the report. “For the first time the US surpassed 1,000 megawatts of installations for one year. We're no longer talking about megawatts of installations, we're talking about gigawatts of solar being installed annually. In the fourth quarter alone, we installed more solar than was installed for all of 2008 and 2009 combined.”

In the fourth quarter, 776 megawatts of solar were installed, according to Shayle Kann, Managing Director of GTM Research's solar practice. That represents 115 percent growth over same quarter of 2010.

“The solar industry in the U.S. just keeps getting more interesting to us. It also keeps getting more complicated and difficult for us to track,” Kann said during the conference.

But that’s a good thing.

“More impressive than the growth is that it grew everywhere,” said Kann.

The report tracks three segments, residential commercial and utility.

Residential grew the least at 11 percent year-over-year growth. The growth stems largely from the third-party ownership programs—leases and power-purchase agreements, according to Kann.

“This has drastically reduced the up-front costs which is always the primary barrier to solar at the residential level,” he said.

The non-residential market saw a growth rate of 127 percent, largely in California and New Jersey.

The utility-scale market, however, saw the most growth, expanding by 185 percent in 2011 over 2010, Kann said.

“We’re really starting to see high volumes of large projects completed in the U.S. and the size is just getting bigger and bigger. I think 2012 is the first year in which we will have projects over 100 megawatts completed,” he said.

The future for solar installations looks bright too, despite losing incentives, according to Resch.

“The U.S. is now poised to install more than 25 gigawatts of new solar between now and 2016,” he said.

At that point the U.S. is expected to be among the biggest markets for solar in the world.