Dow Chemical is ready to launch so-called solar shingles that have been developed thanks partly to public funding.

The Midland, Mich.-based company plans to roll out the shingles in "limited quantities" in North America in mid-2010. First customers will come through partnerships with homebuilders Lennar and Pulte Homes.

Dow has talked about the solar shingles for a few years now. Back in 2007, it received $20 million from the U.S. Department of Energy to develop solar energy-generation products that could be incorporated into building materials and serve both as protective layers of a building and a solar power generator. The solar shingles would take place of the conventional asphalt shingles on parts of a roof that get a good amount of sun.

As an industry giant with hefty resources, Dow will be a formidable competitor in the solar market. The company will not only aim to take business away from manufacturers of conventional solar panels, it also will be jostling with other developers of building materials that also can produce solar energy.

Building-integrated solar products offer the key advantage of being less obtrusive, and appeal to those who want to camouflage the existence of a solar energy system on their rooftops. 

But the limited choices on the market today aren't as efficient at converting sunlight into electricity as conventional solar panels. Dow has yet to disclose the pricing for its solar shingles, which are undergoing UL testing for product safety and performance. 

Roofers who want a slice of the solar market also would find lower installation costs with solar shingles than with solar panels, which require more specialized skills, Dow said. An electrician would still be needed to run the wires from the roof to an inverter and the home. 

Dow is working with Global Solar Energy, a developer of copper-indium-gallium-selenide (CIGS) cells, to develop the solar shingles. Last month, Global Solar said building-integrated products featuring its solar cells would appear in 2010 (see Global Solar: BIPV Market or Bust).

Dow didn't disclose how well its solar shingles would be able to convert sunlight into electricity, a key measurement for determining whether how soon a homeowner could get a return from their investments. That calculation would be difficult to come by if the shingles are installed by homebuilders and the cost is blended into the overall home sale prices.

Moisture can significantly hamper the performance of CIGS cells, so making sure that the cells are tightly sealed is critical.

Global Solar currently assembles cells into strings and sell them to makers of conventional solar panels that use glass to encase the strings. Each string is made up of 18 cells, the company said. The average efficiency of the strings is between 10 percent and 11 percent.

Other solar cell makers that also are targeting the building market include Ascent Solar Technologies in Colorado and United Solar Ovonic (Uni-Solar) in Michigan.

Uni-Solar lined up a prominent player in the roofing material business earlier this year. Denver-based Johns Manville, a Berkshire Hathaway company with 151 years of history, plans to buy Uni-Solar's amorphous-silicon thin films and assemble them into its termaplastic polyolefin (TPO) roofing membranes at its own factory in Alabama (see Roofing Giant Johns Manville Enters Solar Market).