Silane-Free Coating Nearly Eliminates Light-Induced Degradation in Solar Cells
Sixtron has introduced a silane-free antireflective passivation coating that not only eliminates the need for the costly silane infrastructure, but gives monocrystalline solar cell produced a considerable boost in efficiency guarantees in the field.
Aaron Hand, Editor-in-Chief -- PV Society, 1/27/2010
Sixtron Advanced Materials (Montreal), aiming to provide the PV industry a safer coating solution that could meet the performance of silane-based materials, has developed what turns out to improve light-induced degradation (LID) by at least 88% over traditional silane-based SiNx antireflective passivation coatings. The results have been confirmed by benchmarking at the Georgia Institute of Technology.
About a year ago, Sixtron introduced its SunBox on-site gas generation system, a silane-free system geared toward eliminating the cost of dealing with the hazardous properties of silane. Now the company is introducing its Silexium technology, a silicon carbon nitride antireflective passivation coating that it says nearly eliminates LID, a common problem that reduces the efficiency of modules in the field by up to 5% in the first few hours of exposure to the sun.
Silane-free Silexium antireflective coatings nearly eliminate light-induced degradation (LID) in monocrystalline solar cells. (Source: Sixtron Advanced Materials)
"When Sixtron came to market with the SunBox on-site gas generation system a year ago, what originally attracted a lot of interest was simply the fact that we could deliver parity with the performance of silicon nitride films using our silane-free replacement," said Bates Marshall, vice president of sales and marketing for Sixtron. But what Sixtron CTO Junegie Hong began to discover last summer was that solar cells coated with Silexium films "are nearly immune to this problem of light-induced degradation, which haunts monocrystalline solar cells."
As an example, an 18% efficient monocrystalline cell, once it's exposed to the sun's UV rays for the first time, could have its performance drop to 17.1% within six to 10 hours of exposure, Marshall noted, adding that every 0.1% of that performance is a hard-won battle by the industry. "So we're essentially, with this Silexium technology, giving that performance back to the cell manufacturers."
LID is typically accounted for in the transaction between the cell and module companies, with the warranties provided by the module companies accounting for the behavior. "Because the economics of the industry are literally people paying for energy generation, everything that we give back goes straight to the bottom line of the cell manufacturers," Marshall said. "It's a leverage effect of a tiny improvement in efficiency having a huge impact on the profits of the cell manufacturers. And these days, I don't have to tell you what's going on with the profitability of most cell manufacturers. They're really looking for any possible way to squeeze some profits out of their supply chain."
Sixtron is releasing the Silexium technology now just for monocrystalline cell manufacturers. "It is applicable for multicrystalline, but the performance of the layer in a multicrystalline cell is not quite there," Marshall said, noting that the company needs the performance to be at least at parity with the incumbent process.
