The Obama stimulus planted the seeds, and now big solar is sprouting in the desert Southwest.

The U.S. Department of Energy on Tuesday announced that the Agua Caliente solar project in Yuma, Arizona is now fully on-line. The installation is capable of producing up to 290 megawatts of power, making it the world’s largest photovoltaic plant. Agua Caliente was backed by a $976 million loan guarantee, and its completion came just days after the 250-megawatt Genesis concentrating solar project went on-line in California, and less than three months after the Ivanpah power tower project, also in California, began feeding into the grid.

Agua Caliente, built by First Solar using its thin-film panels, had been operating at 250 megawatts since September 2012, before the finishing touches were recently put on the project. Power from the plant goes to Pacific Gas and Electric, the Northern California utility, under a long-term power purchase agreement.

Two giant, DOE-backed PV plants remain under construction in California, and the head of the loan program, Peter Davidson, said in a statement that they will be completed “by the end of next year.” Davidson also took advantage of the opportunity to reprise an argument the DOE has grown fond of in recent months -- that after the DOE funded its projects, the door to privately backed big solar swung open.

“Ten additional PV projects larger than 100 megawatts have been announced -- all without any DOE financing,” Davidson said. “In 2013, 2,847 megawatts of utility-scale solar was installed in the U.S., a 58 percent increase over 2012. Since 2010, total solar capacity in the U.S. has increased by an amazing 418 percent.”

There are signs, however, that the flow of big solar projects in the desert might ebb. A count by the Los Angeles Times earlier this year found that just twenty of 365 solar plants in the application process since 2009 were “on track to be built.” A scan of the California Energy Commission’s online power project status page shows a variety of projects that have stalled or fallen by the wayside. Just last week, the CEC terminated the planned 250-megawatt Ridgecrest Solar Power Project, a solar thermal wannabe whose fate was sealed when developer Solar Millennium went bankrupt in 2012.

Financing projects remains a challenge, and there’s the added factor of utilities not feeling such a pressing need for new renewables; the California Public Utilities Commission in its most recent quarterly report said that at the close of 2013, California was “on track to meet its interim requirement of 25% renewables by 2016, and is well positioned to meet 33% by 2020.”

Still, for the DOE loan program, which is still strongly associated with the Solyndra failure, the solar successes are clearly sweet vindication. The timing couldn’t be better, either: The DOE recently issued a draft solicitation for a new batch of renewable energy loan guarantees, which would be the first since those tied to the 2009 stimulus closed in September 2011.

While those earlier loans were targeted toward big electrical generating projects, in the new round of loan guarantees, which could total as much as $4 billion, the DOE says it is aiming to catalyze the market for technologies in energy storage, waste-to-energy and drop-in biofuels, among others.

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Editor's note: This article is reposted from Breaking Energy. Author credit goes to Pete Danko.