Solar Photovoltaics — Ostensible Breakthrough
Frequent commenter and all-around good guy Tim Kingston sent me this video on an ostensible breakthrough in solar PV for my comment.
I see claims like this constantly, and I’m never sure exactly how to evaluate them, since this isn’t my area of expertise. My own sense suggests that this particular one is not credible, based on the way it’s presented and some of the claims it makes. Yes, of course the world needs a way to minimize photons from reflecting, as well as from passing straight through. And yes, the way to deal with this is to get photons bouncing around, i.e., in three dimensions. My wife and kids know this. In fact, it’s possible that my dogs know this, since they hang out in my office and hear it so often.
But trapping photons in the way they describe will not produce the outrageous increases in efficiencies they claim.
When I go to solar shows, I run into hundreds of people who have made this subject their life’s work. Did these Solar 3D people make a breakthrough where others have failed? They do have a video… and one of their people does have a Russian (Ukranian?) accent; perhaps he’s one of these super-scientists from that part of the world. And … (wait for it) … they’re only one measly year away from commercialization.
Tim: Sorry to be sarcastic. I guess I would say that it’s possible, but I would have to think this is extremely unlikely.
I would rate this one plausible as the cell uses three different processes to improve efficiency – in the first, the 3D shape of the cells results in superior light trapping. This however is likely to result in gains of only around 15% on its own.
The main advance is reducing the distance an electron must travel before passing on its charge to a wire. This has the effect of reducing the likelihood of recombination which is analogous to internal electrical resistance. Reducing recombination losses, is I think one of the major differences between a high efficiency and a normal solar cell. This will probably have the effect of also lowering the cell’s operating temperature as more of the energy in the photons is extracted rather than heating up the cell.
There is also a third somewhat smaller cause for improved efficiency – back contact – so no wires shading the front of the cell.
So far, we only have the company’s own claims as to the cell’s efficiency. This being the case, I would be keen to see corroboration of their claims by a respected lab such as NREL or Fernhoffer. Hopefully, they will soon submit their cells for such an evaluation as I can’t see them finding it easy to attract major investment unless it’s from Panasonic the makers of the equipment on which they fabricate their cells (who are capable of their own internal corroboration) without some sort of external independent confirmation.
I like your response here, Craig. I’ve been lurking around your very interesting and informative site since pretty much the beginning, but I was compelled to comment when this company came up.
I’ve been keeping an eye on this company for a while, as it’s close to my alma mater – I like to fantasize about moving back to Santa Barbara!
I have no special insight on the efficiency improvement claims – some of them certainly sound logical. I certainly can’t disagree with anything Gary says above. And if even just that part were true, it would have a huge impact when current module companies are only making small incremental improvements! But combined with some of the other claims, it just starts to sound like making too many promises to try to pump some investments in…
My BS sensor goes off when I see quotes like this on the technology page of their site: “Solar panels using Solar3D cells will not need tracking systems that follow the sun to maintain high efficiency because of its wide angle light collection feature.” A “wide angle collection feature” can’t make up for the cosine loss, which dwarfs the effect of reflectance of the module surface. You can’t catch photons that don’t hit the module at all!