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Cool Earth Gets $21M for Inflatable Solar

Cool Earth Solar’s photovoltaic (CPV) balloons look a bit like those cheesy mylar balloons that you might have bought for your honey this Valentine’s Day. But they’re a lot more useful. In fact, Livermore, Calif.-based Cool Earth yesterday closed a $21 million Series A round to fund their innovative and inflatable solar collectors.

Although Cool Earth’s inflated mirror concentrators look just like oversized conventional foil balloons, one half is reflective mylar; the other, clear film. Inside the bubble is a high-efficiency PV receiver. Designed for utility-scale solar energy, the balloons are lightweight and easy to string up but rugged enough to withstand 100 mph winds, according to the company. And all of the delicate and expensive PV components are protected inside.

cool earth CPV

The startup says it will use the money to hire more personnel and build solar power plants. Cool Earth is aiming to have a power plant up and running within a year, founder Dr. Eric Cummings told us yesterday. He says they are looking to build a plant “in the 10-megawatt range,” which would use 10,000 such inflatable devices and be spread out over some 80 acres. They’re also actively looking to sell power to electric utilities, though Cummings was mum on which utilities they are approaching.

Cool Earth says that this is just the initial closing of the round, and that it could extend it over the next 60 days. The company closed a $1 million round of angel investing last June.

The CPV from Cool Earth is an elegant and simple solar concentrator that uses a fraction of the materials used by other CPV makers. But because their collectors have so few materials, they do require active water cooling to keep the units from overheating. Cool Earth, however, thinks this is is small price to pay for the simple manufacturing and installation of the concentrators.

balloon weights

14 Responses to “Cool Earth Gets $21M for Inflatable Solar”

  1. Cool Earth Solar’s photovoltaic balloons are a bit of an eye sore, but there are lots of viable, eye-pleasing solar alternatives. If you’re interested in solar power or any other alternative energies, check out It has hundreds of case studies on emerging green technology and solar energy. It’s also the largest b2b green directory on the web.

  2. warning!!!
    This photos are complete fake
    The idea is really cool (and stolen)
    But the shape of sized party balloons on pictures CAN NOT concentrate solar energy at levels declared in text
    Remark the pints where photovoltaic elements must be: do you see any concentrated light, 400 times brighter than sun?
    Do you ever see REAL solar concentrator at work? Search the web for compilations.
    You can check up the concentrator using party balloon – some of them have only one side aluminized.

  3. Green energy is definitely the best solution in most cases. Technology like solar energy, wind power, fuel cells, zaps electric vehicles, EV hybrids, etc have come so far recently. Green energy even costs way less than oil and gas in many cases.

  4. If these things develop like the wind turbines, they’ll probably have mountain size balloons floating on the ocean, though I wouldn’t like to be in the vicinity if they popped..