HelioVolt claims CIGS solar efficiency mark
There's a race to produce solar cells from CIGS that approach silicon's efficiency. HelioVolt says it's getting there--and fast.
Solar upstart HelioVolt on Monday will announce that it has reached 12.2 percent efficiency with its CIGS solar cells, setting another mark in the race against competitors and silicon.
Company CEO BJ Stanbery will present a paper at the IEEE Photovoltaics Specialists Conference where he will disclose the efficiency threshold which HelioVolt has reached in its labs. The well-financed company expects it can go much further in converting light to electricity.
More significant than the actual number is the fact that HelioVolt hit 12 percent efficiency with its manufacturing process, which it says can turn out a cell in six minutes.
The National Renewable Energy Laboratories (NREL) earlier this year said that it attained 19.9 percent efficiency for a solar cell made out of CIGS (copper indium gallium selenide), an alternative to traditional silicon.
NREL used a technique called co-evaporation where active chemicals are immersed in a solution, which then gets removed. That process can take 40 to 50 minutes, according to HelioVolt.
Another CIGS company, Global Solar Energy, also uses co-evaporation. Earlier this year, it said it broke the 10 percent mark with its commercial products and expects to hit 13 percent or 14 percent this year.
What matters more than the efficiency record is the speed with which solar companies can manufacture. Ultimately, high scale is what brings costs down, said John Langdon, HelioVolt's vice president of marketing.
In fact, when HelioVolt first delivers product at the end of this year or early next year, Langdon said that the efficiency will be between 10 and 12 percent because it's a more efficient process.
"Everybody has known for years that the cost of CIGS film is much less than silicon--something like 3 cents on the dollar. The issue has always been making it fast enough," he said.
Langdon said the company's FASST process is like making a grilled cheese sandwich where two pieces of bread contain different chemicals. Under heat, the two layers of "cheese" bind together to form a cell.
At first, the company plans to put the cells onto a glass substrate for solar panels. Later, it intends to put the flexible cells onto a plastic substrate so it can be integrated into building materials, like roofs or awnings.
Competitor Nanosolar claims an efficiency in the nine to ten percent range for its commercial products which started shipping at the end of last year and higher results in its labs.
For comparison, commercial silicon cells convert light to electricity at about 14 percent to 20 percent. But efficiency doesn't translate into commercial viability.
Companies are pursuing alternative materials to silicon to get around the high prices and demand associated with it. Thin-film cells use less material than traditional cells.
Solar high-flyer First Solar uses thin film solar cells made out of cadmium telluride that are less efficient than silicon.
But working with CIGS is notoriously difficult, particularly manufacturing at large scale.
Another venture-backed CIGS company, Miasole, had to set back its initial plans after technical difficulties and efficiency levels that were only 4 percent to 6 percent.