CIGS companies eye building-integrated photovoltaics

Thin-film solar power companies want to integrate solar cells with buildings, but they still have a way to go.

Hanna Sistek
4 min read

AUSTIN, Texas--"It's like a great big grilled cheese sandwich machine."

That's how solar power company HelioVolt's vice president of marketing and sales, John Langdon, describes the company's pilot line for CIGS thin-film photovoltaics, a technology that a raft of companies are betting on to lower the cost of solar energy.

"You have the Gruyere cheese on one side and the Swiss cheese on the other; we make them react with one another and stick on the bread," Langdon continued when CNET News.com visited the company's headquarters in Austin.

HelioVolt's "grill sandwich" pilot line Hanna Sistek

Replace the cheeses with chemicals specifically prepared for the process and the toast with a thin layer of photovoltaic absorber, and you'll have the essence of HelioVolt's manufacturing technique, called FASST. When the pre-cursed materials react, they form the CIGS, a combination of cadmium, indium, gallium, and selenium.

That "cheesy" layer is put on a sheet of weather-sealing glass and then covered with another glass layer. The company claims that FASST is 10 to 100 times quicker than the last step of the manufacturing process used by some of its competitors. This is because the CIGS reaction is a one-step process, instead of first "making the cheeses" and getting them to react after. A solar cell takes six minutes to produce in this fashion.

Last year, HelioVolt raised $101 million in B-round funding, which it will use to build its first factory, with an initial capacity of 20 megawatts per year.

One of the markets for its thin-film cells is building integrated photovoltaics (BIPV). Earlier this month, HelioVolt announced a partnership with construction firm Architectural Glass and Aluminum to enter that market. AGA makes curtain walls--non-weight-bearing facades--for buildings, and HelioVolt will incorporate thin-film cells in the spandrels of AGA's curtain walls.

When it starts production, HelioVolt will begin selling its panels to large solar farms. The company aims to start shipping CIGS panels by the end of the year. The next step is to use BIPV for commercial buildings. The company hopes it will have prototypes for spandrels by next year and products by 2010.

HelioVolt believes that integrated photovoltaics is the future as far as construction materials are concerned, and claims that an average American home would be able to generate 3 kilowatts of electricity during peak hours. This might, in the best-case scenario, be enough to cover the energy needs of the average household.

Solar cell roof tiles
But to get a real breakthrough, BIPV prices need to come down from today's average of $7 or $8 per watt. The price tag for equipping an average American home lies around $20,000, according to HelioVolt. That includes a 25 percent savings from not having to retrofit the solar panels on the roof (the mounting actually makes up half of the cost), the company claims.

The Department of Energy's Solar America Initiative program has set a goal of making solar electricity cost-competitive with grid electricity by 2015. Developing BIPV is a part of that program. Dow Building Solutions, a business unit of The Dow Chemical Company, got a three-year $9 million grant a year ago to do just that.

Dow is developing flexible solar roof shingles as part of the program, and teamed up with CIGS company Global Solar a couple of weeks ago.

Global Solar is ahead of HelioVolt, with production running at a 40-megawatt capacity from their plant in Tucson, Ariz., and another that's expected to produce 30 megawatts should be up and running in Berlin by the end of 2009. Instead of printing, the company uses a co-evaporation technique to deposit the CIGS material onto 1,000-foot-long rolls of thin stainless steel. They can ship the rolls directly to clients, who themselves may cut out the desired size of the solar cells, and then coat them with glass. This gives Global Solar the advantage of not having to ship the heavy and fragile glass themselves, but creates more work for the customers.

Global Solar is not involved in the BIPV creation process, it just sells the PV material to Dow, and is open to more partnerships with building companies. Tim Teich, vice president of sales and marketing at Global Solar, claims that building companies are rushing to team up with solar corporations. "I get approached every single day," he said.

HelioVolt doesn't have any products--such as roof tiles, shingles, or wall coating--ready yet. It didn't even have any test samples of its CIGS cells to show when I visited. The company still has to figure out how to print the photovoltaics on materials other than glass, which can be expensive. The next materials in line are metal foil and plastics.

BIPV is currently being produced by companies like Suntech Power Holdings, or the much smaller Open Energy Corporation, integrating classic silicon wafers into roof tiles. Other players in the area include Sharp, BP Solar, and SunPower PowerLight.

CIGS are cheaper to manufacture than silicon wafers, which today constitute about 90 percent of the solar market. By 2012, the CIGS market share will increase to 25 percent, according to Lux Research.