Retail giant Walmart said it plans to install solar panels on top of about half of its roughly 50 Massachusetts stores as early as August as part of an expansion of solar power in the state.
The installations for the 27 stores are still in the engineering phase, and local permits must be obtained, Walmart officials said. But once the projects are done, they will be capable of generating a total of about 10.5 megawatts worth of energy, enough to power up to 2,600 homes.
“On average, the systems we’ll be using in Massachusetts will provide from 10 to 15 percent of each store’s power requirements,’’ said David Ozment, Walmart’s director of energy programs. “We’re very optimistic that we’re going to save some dollars over time.’’
Walmart’s plans were spurred, in part, by a 2008 initiative of Governor Deval Patrick to encourage the use of alternative energy at large retail buildings where flat roofs would be ideal for solar projects. Other retailers have installed solar arrays, including Shaw’s Supermarkets, which added solar panels to its stores in Webster and Burlington, and Stop & Shop, which completed installations at locations in Dorchester, Dedham, and Somerville.
The governor’s push for big-box retailers to use solar power is part of an effort to install 250 megawatts of solar generating capacity in Massachusetts by 2017. That is enough to power at least 37,500 homes.
Currently, there are 105 megawatts installed in the state - or just over 40 percent of the administration’s goal. Walmart’s new solar installations in Massachusetts, Patrick said in a statement, are a boost for the effort.
“This is another step forward in the Commonwealth’s clean-energy mission,’’ Patrick said, “and will help make Massachusetts a better place for the next generation.’’
Solar panels already top several Walmart stores in warm-weather states such as California, Hawaii, and Arizona, and the company more recently began constructing installations at locations in New Jersey and Colorado. In total, the company has 50 megawatts worth of generating capacity operating on its roofs across the country, or enough to power up to 12,500 homes.
Walmart’s solar installations will be built by Greenskies Renewable Energy LLC, a Connecticut-based company that will own and operate the solar generating system, and sell the power produced to Walmart for use in its stores. Walmart would not disclose the pricing, but said its goal is to meet or beat utility charges.
Greenskies is not getting direct financial aid from the state for the project, but will be able to sell the renewable energy credits attributed to the solar panels to energy producers, who must meet state goals to reduce greenhouse-gas emissions.
Greenskies also expects to apply for federal tax credits meant to finance the construction of renewable energy resources.
“Currently, we are engineering the first two phases, which is just over 10 stores,’’ said Andrew Chester, senior vice president at Greenskies. He declined to put a price tag on the project - which will take about 18 months to complete - but said the standard industry installation cost is about $3 per watt. At that price, Walmart’s solar installations would cost about $31.5 million.
The Walmart project is another sign of the growing potential of the state’s solar industry, said Peter Rothstein, president of the New England Clean Energy Council, an industry group based in Boston. According to state energy officials, there are nearly 200 solar installation companies working in Massachusetts.
“A lot of the early installations were in the Southwest, which a lot of us think of as the ideal solar climate,’’ Rothstein said. “But I think this is a very strong indication of how solar makes economic sense here in New England, as well.’’