by Chris Morrison, November 26, 2008
A common idea for making solar cells more effective is to concentrate sunlight on them with lenses and mirrors. But for thin-film solar, which is made up of cheaper materials than typical silicon-based photovoltaic cells, these focusing techniques are hardly mentioned. Optony hopes it can bridge this gap with a new technology.
At first glance, the disadvantages to concentrating sunlight on thin-film seem to outnumber the advantages. Thin-film solar is not only dirt cheap, it is also fairly inefficient at converting sunlight to electricity. That means there’s little cost benefit to adding equipment like mirrors, which may well cost more than the thin-film itself. Also, known thin-film compositions tend to degrade under intense sunlight.
But Optony’s founder, P.R. Yu, says that his years of experience at the National Renewable Energy Laboratory gave him the pick of several good technologies to pursue — and he chose thin-film technology. The material he chose to work with, he says, is resilient to heat, and can thus clear the first hurdle of surviving focused sunlight.
More interesting, Yu says that the efficiencies he can achieve by concentrating thin-film will easily exceed 20 percent — higher than standard photovoltaics, and about double most thin-film cells by themselves — yet at an even lower cost, he claims.
That could turn out to be a reasonable assertion: Significant cost cuts can be made by phasing out the expensive equipment that regular concentrating photovoltaics use, like bulky permanent bases and multi-axis trackers to keep the panels aimed precisely at the sun.
Such equipment is necessary because the highly-efficient solar cells typically used for concentrating solar are very small, and must be carefully controlled. An Optony unit would use a much larger thin-film cell, which would allow for more relaxed — and less expensive — tracking and cooling methods. The aim is to keep costs for all components down so that the concentrating units can be on par, cost-wise, with fossil fuels, even without government subsidies.
The Sunnyvale, Calif. company is still in the development stage, with the potential to have a finished product in about a year. It’s currently looking for a first round of venture funding.