Hot kilowatts: Infinia, Stirling Energy Systems, eSolar get money

Three solar-thermal companies have raised money in the past week in a sector that's showing life, despite a choppy investment environment.

Infinia on Tuesday said it has taken $7 million from Asian contract manufacturer Foxconn Technology Group, part of a total of $57 million in a Series B round first announced in February.

Infinia's dishes use the sun's heat to generate electricity with a Stirling engine.

(Credit: Infinia)

The company uses a dish to concentrate sunlight onto a Stirling engine, which makes electricity. It intends to sell its 3-kilowatt devices to small-scale utility plants.

On Monday, eSolar said it has raised $130 million from Idealab and Google.org. Its solar-thermal systems, designed for utility-scale power plants, use mirrors to reflect light onto a tower that turns a turbine.

And last Thursday, Stirling Energy Systems announced a $100 million investment from renewable-energy developer and waste management company NTR.

Stirling Energy Systems makes a huge concentrator dish that generates heat to turn a Stirling engine that makes electricity. It's under contract for two power plants in the Mojave Desert that would initially generate 800 megawatts of power.

Solar-thermal technology has been around for decades, and Stirling engines date back to the 19th century. But the high cost of silicon-solar cells has made solar-concentrating systems more attractive in desert areas like the Southwest United States and Spain.