Cool Earth Solar said Thursday it got a $21 million lift forsolar-concentrating technology that uses inflated mirror concentrators to turn sun rays into electricity.

The Livermore, Calif.-based company didn't disclose who paid for the round. However, Cool Earth did say additional closings may occur in the next 60 days.

The company also closed a $1 million angel round in May.

Thursday's deal was part of a recent series of news about large-scale solar technologies.

On Monday, solar-concentrating company Infinia Corp. snagged $50 million in a second round of financing for the commercial launch of its solar systems that draw on engine technology to convert heat from the sun into electricity (see Infinia Gets $50M for Engine-Powered Solar).

And earlier this month, Emcore and SunPeak Solar said they are teaming up to develop large-scale projects in the U.S. Southwest. Others such as Solel and Ausra also are developing projects.

The latest funding will help expand the company's business team and bring its technology to the market.

According to Cool Earth's Web site, the company is negotiating to sell utilities electricity made from the company's concentrating-solar systems.

In general, concentrating solar takes sunlight from a larger area and uses lenses or glass to direct and concentrate it onto smaller solar cells.

But Cool Earth is offering a twist on the approach. The company inflates a balloonlike device made of thin, reflective material to catch and focus the light onto solar cells.

Cool Earth claims it is able to produce electricity at a cost lower than that of natural gas-fueled plants. It also asserts its technology is cheaper than traditional concentrating technology that includes more expensive items like metal-supported mirrors.

But when it comes to surviving outdoor elements, it's unclear which approach would endure.

Traditional mirror technology is often firmly bolted down to the ground. But often the devices come equipped with multiple-part tracking systems that sometimes break down as they follow the sun.

In comparison, Cool Earth's concentrating-solar balloons are suspended in the air using a system of poles and cables.

But as every electric utility could probably attest, it's not easy keeping electricity flowing through suspended systems when heavy storms hit. Cool Earth said its technology could withstand 100 mph winds.

Although Cool Earth is offering a unique approach to concentrating solar, it's not alone in pursuing different methods.