Investors had been anxiously awaiting news on the loan guarantees, which will sharply lower the costs to construct the plants that will have a total capacity of about 1,330 megawatts, about 30 percent more than a large nuclear power reactor.

First Solar is the world's largest maker by market value of the photovoltaic solar panels that turn sunlight into electricity, and its thin-film panels are the lowest cost in the industry.

The DOE's program that grants renewable power projects the guarantees on loans to secure financing will expire later this year, removing a key support for the industry that is still dependent on subsidies in most locations to compete against fossil fuels.

Declining subsidies in key European markets have trimmed demand there, leading to a glut of supply that has pushed solar panel prices down more than 10 percent so far this year, pressuring solar companies' share prices.

The Department of Energy said the conditional loan guarantees included $680 million for First Solar's Antelope Valley Solar Ranch, $1.88 billion for its Desert Sunlight project and $1.93 billion for its Topaz Solar project.

The company expects that the projects will create a combined 1,400 jobs in California during peak construction.

Shares of First Solar jumped 7.4 percent to $139 in early trading on the Nasdaq.

Those shares had dropped more than 35 percent from their February high at $175 to the lows reached earlier this month.