Combined PV/Thermal Units: In the Works?

Solar energy systems that combine solar thermal heating and photovoltaic (PV) electricity are getting a lot of attention lately and, yes, several different designs are in the works, if not available already. The idea is this: PV solar panels alone have an average efficiency of 10-15%. That means that roughly 85% of the remaining solar heat is wasted. Solar thermal collectors, on the other hand, utilize a high portion of the solar heat striking them.

So on one hand you have a large portion of usable solar heat going to waste. On the other you have a collector that can use as much as 70% of solar radiation on its own. A logical question ensues: Why not combine the two? And that’s exactly what solar developers and manufacturers are up to.

The American Solar Energy Society has published a report that outlines the benefits of combined PV/thermal applications. That report claimed an overall efficiency of 50% for the hybrid SolarWall system tested.

Now several manufacturers are jumping on the bandwagon. BrightPhase Energy recently released their three-in-one solar system, Photensity, that acts as a PV panel, thermal collector, and skylight all at the same time. PVT Solar is yet another company working on combining PV and thermal to create high efficiency solar systems.

While you might think PV panels, which work at cooler temperatures, and thermal collectors, which thrive on heat, would clash when put together, evidence seems to point to the contrary. Even if some of the thermal collector’s efficiency must be sacrificed, the resulting rise in PV efficiency makes up for it, creating an overall upswing in system output.

Combined PV/Thermal systems are still very young and still relatively untested on a wide scale, but if they get this one down, it’s hard to believe it won’t have a serious impact on the industry.

Photo: BrightPhase Energy’s Photensity

Posted on February 24th in Solar Information by Dan.