Wal-Mart to try thin-film solar technology

SAN FRANCISCO (Reuters) - Retail giant Wal-Mart Stores Inc plans to expand the use of renewable energy in its stores by installing thin-film solar panels in up to 30 of its locations.

This would be first time that Wal-Mart, which already has solar installations in 31 other sites in California and Hawaii, would use thin-film solar technology to generate power.

"Until now, all of our solar projects have been with traditional crystalline panels," a Wal-Mart spokeswoman said in an email statement.

The solar systems, which will be installed in up to 30 sites in California and Arizona, will supply up to 20 to 30 percent of the total energy needs for each location, the company said.

Wal-Mart has a broad goal to one day use only renewable energy and create zero waste.

The retail giant has embarked on a number of green initiatives in the past year, including increasing its use of solar power and announcing plans to roll out an index that will measure the environmental impact of the products it sells in its stores.

It also has a goal to cut greenhouse gas emissions from its global supply chain within five years -- an effort Wal-Mart has said was equivalent to taking more than 3.8 million cars off the road for a year.

Wal-Mart said the new solar systems will be designed, installed, owned and maintained by privately held California company SolarCity.

Thin-film panels absorb light more easily than crystalline silicon so require less semiconductor material and are cheaper. But they tend to be less efficient in energy conversion.

Wal-Mart also said it planned to use both the newer copper indium gallium selenide (CIGS) and the more-established cadmium telluride thin-film technologies.

First Solar, one of the world's largest solar module makers, is the leader in thin-film cadmium telluride panels while solar panels utilizing the CIGS technology are made by startups such as Silicon Valley-based MiaSole.

Currently, thin-film makers hold around 20 percent share of the solar market that is currently dominated by polysilicon-based panels, made by large competitors such as Suntech Power Holdings and SunPower Corp.

(Reporting by Poornima Gupta, editing by Leslie Gevirtz)