Clean Power photovoltaic thermal solar

Published on April 5th, 2012 | by Zachary Shahan


UK Company Likes Its Energy Naked

April 5th, 2012 by  

A cleantech start-up out of the UK, Naked Energy, has created a technology that’s a little over my head, but that looks quite cool.

Basically, one of the key challenges of solar photovoltaics (PV) is that their efficiency drops if they get too hot. Naked Energy, in response, has created a hybrid solar PV and thermal panel that it claims improves efficiency at high temperatures by 50% or so.

“By efficiently drawing heat away from the solar panel for space heating, hot water, de-salination and cooling the photovoltaic cells are maintained at an optimum operating temperature,” the company writes. “This results in significantly higher electrical output than standard photovoltaic panels.”

“Both energy outputs are optimized replacing the need for two separate conventional panels (PV and Thermal), dramatically reducing installation time and cost whilst maximizing useable installation area.”

The general term for these is PVT (photovoltaic thermal) solar. Naked Energy’s specific product is called Virtu™.

photovoltaic thermal solar

So, how hot do normal PV panels have to get before their efficiency starts getting hit? Apparently, just 25ºC, above which they start losing about half a percent of their efficiency for every extra degree. And these panels can reach as high as 70-80ºC!

How does Naked Energy’s technology transfer heat away from the PV cells while making it available for heating water? The solar PV cells are stuck inside a vacuum enclosed by glass (see image above).

“The vacuum tubes have low thermal losses and will produce abundant hot water / heat regardless of being installed in hot or cold climates. The annual yield depends on the application, local climatic conditions and quantity of panels installed.”

The company is also working on some thermal-only tubes for very hot climates. “For installations requiring high temperatures for thermally driven cooling or heat storage we are producing matching ‘thermal only’ vacuum tubes, which will be able to produce significantly higher temperatures.”

These PVT panels are still being evaluated, by Imperial College London, and results will be published in 2012.

As always in such cases, it’s hard to know at such an early stage if the improved efficiencies offset the added costs of production enough to make this new technology a commercially competitive option (for the targeted market). We’ll see. For now, it certainly looks like an innovative and logical way to deal with a common PV efficiency problem.

Source: Naked Energy

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About the Author

is tryin' to help society help itself (and other species) with the power of the typed word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession, Solar Love, and Bikocity. Zach is recognized globally as a solar energy, electric car, and energy storage expert. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in.

  • RobS

    Thisis definitely the future, the first time I learnt two facts; heat degrades solar PV output, and space and water heating accounts for >50% of most homes energy consumption the combination of solar panels and removing the wasted heat for space and water heating instantly became the ultimate combination. There have been systems for air heating, water heating and electricity generation for some time but having two or even three different types of panels on our roof is expensive and aesthetically poor. Combining these technologies into one integrated system is a perfect match and hopefully they can bring some products to commercial availability soon to take advantage of the >100% Y/Y growth currently occurring around the world.

    • Maps

      Thing is, the efficiency of the solar cells is increased only if the temperature of the water output is decreased, so your hot water will actually be lukewarm and unfit for most purposes other than space heating.

  • Saurdigger

    The SolarWall company’s had an analogue to this for a while (see here:

  • dcmeserve

    I am looking towards both PV and solar water heating for my house. This sounds like it would be a great fit, but looks like won’t be ready in time for me…

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