Silicon, silicone and next-gen solar

No, those aren’t typos up there. There is a difference between silicon and silicone, according to Steve Swanson, an engineer for Dow Corning.

Swanson was at the the Coachella Valley Economic Partnership’s Renewable Energy Roundtable Thursday, to talk about how silicone can boost the production of electricity from silicon cells in solar panels — and what he and Dow Corning hope will be the next generation of solar panels.

It’s all about how solar cells are put together. In a grossly oversimplified explanation — mine, not Swanson’s — your basic cell has glass and the silicon wafers, but then you need some layers in between to hold it all together. What is used in most cells is called EVA, or ethylene vinyl acetate, which is oil-based.

Silicone — which is silicon and other chemicals — has been used in some solar panels in the past, for example, panels on space satellites, because it can withstand major extremes of temperature. It also is crystal clear, which EVA is not, and lets in UV rays that can increase electric production. But silicone has long been much more expensive, hence not practical for commercial and residential solar panels.

That’s changing, Swanson said. Dow Corning has been testing panels using silicone, instead of EVA, between the glass and silicon layers, and the company has found that silicone panels produce more power and they operate at higher efficiency longer. Regular panels lose about 1 percent of their efficiency per year, so by the time a panel has been on your roof 10 years, it’s only operating at 90 percent of the efficiency it did when it was new.  With silicone, the efficiency loss is much less, possibly as low as .2 percent, Swanson said. 

To test the panels out, Dow Corning worked on a case study with SunPower,  the San Jose solar firm that,  just about everyone agrees, has the best panels on the market. The two companies set up an installation with SunPower’s regular panels on one side, and on the other, the same panels but put together with silicone.

The result, Swanson said, was that the SunPower panels made with silicone produced 2 percent more power than the EVA panels.  They also tested the silicone panels against BP Solar panels, which are less efficient than SunPower’s. This time out, on the very first day, the silicone panels produced .7 percent more electricity, but over time that’s gone up to .85 percent.

Solar folks at the roundtable questioned Swanson closely on the silicone panels’ heat resistance. While laboratory tests have looked at how the panels stand up to sudden highs and lows, the desert’s unrelenting sun and summer heat are on a different level all together, they said. 

Dow Corning should be testing the panels in the Coachella Valley, they said.

Swanson said the panels have been tested in Arizona, under conditions similar to the desert. The technology is ready, he said. What Dow needs now is a company willing to invest to manufacture the panels on a large scale. And presumably volume will bring down costs.

That would be key. Right now, silicone panels are still more expensive than EVA panels – for example, one cost projection shown at the roundtable found that a 1 megawatt installation of silicone panels would run about $5.3 million versus $4.7 million for standard, EVA panels.

As we all know, prices on PV have been plunging and more than one good idea — yes, I mean Solyndra –  has crashed in the current market.

This has long been a concern of mine — that cheap panels will overshadow or delay development of new and better solar technologies that, at least to start, are more expensive. 

At the very least,  it will be worth watching how Dow Corning develops this technology and if it finds the investors it needs.

And, before I sign off for the weekend — let’s hear three cheers for American Cab, the local cab company that now has put three hybrid Priuses in its fleet, replacing older vehicles.

According to a press release from the company, it will be adding more hybrids to its fleet over the year – reducing carbon emissions for the valley and reducing gas costs for its drivers by as much as $300 a month.

Sounds good, but don’t expect the savings to be passed on to customers. Cab fares are set by SunLine Transit Agency.