Concentrated PV

This November a CPV start-up will be at an awards ceremony alongside clean-tech heavyweights BrightSource and Tesla. Rawlemon’s Andre Broessel tells PV Insider why.

Gaining recognition for the merits of CPV is not easy right now. So how come a one-man start-up is going to be lining up alongside the solar thermal giant BrightSource and the electric vehicle Tesla for the chance of a coveted World Technology Award this November?

The reason is that the company in question, Barcelona-based Rawlemon, is not your run-of-the-mill outfit. Instead it uses a technology so novel that it seemingly counters the acknowledged laws of optics… and could open CPV up to a whole new range of applications, including building-integrated PV (BIPV).

Here founder Andre Broessel describes what is so special about his ball lens concept.

Q: What is the big deal about using a ball lens for CPV?

A: All concentration products need a lot of sun, but I don’t. I can get double the output of a traditional panel in diffuse light, with 99% transparency, making the lens ideal for BIPV. And I use 75% less silicon per square metre than a traditional panel.

With this system you can get 25% efficiency on a façade, versus about 8% in the best BIPV installations available today. With this, you can build energy-autonomous buildings. With traditional PV you can’t.

Q: What has been the PV industry’s reaction to your concept?

A: I have been to Intersolar two years running and there’s always a lot of interest, but then nothing happens. I think once people understand the concept they start to get worried about what it could do to the traditional PV market.

DLR [the national aeronautics and space research centre of the Federal Republic of Germany] didn’t even want to test it. They just said ‘you cannot say you have found a way to concentrate diffuse light… it’s not possible.’

The Fraunhofer Institute did not respond to my emails when I asked them to certify the product. The patent for this product is in process but there, too, there have been some curious occurrences.

At one point some of the claims I wanted to make were mysteriously dropped off the patent application. But I have my measurements and I will go to the end of the world to get them on stage.

Q: How do you hope to commercialise this product at the moment?

A: What I am developing is a façade model. I have been asked for a mock-up by SOM [Skidmore, Owings & Merrill, an American architectural and engineering firm].

Once I can demonstrate a mock-up to SOM or other architects, a pilot project should be easy to scale up production. And I don’t even need a certification for this.

Q: What other applications do you envisage for Rawlemon’s products?

A: In BIPV, the ball lens gives you five times more possibilities than traditional panels, because of the transparencey. It can also be used for heating; at the focal point of a one-metre sphere I have measured 700ºC.

You can even build a LED-based version and put arrays of lenses together to create a monitor, so this product has multimedia potential.