The Home Depot announced the addition of solar installations at 50 stores as it continues to expand its alternative energy portfolio, essentially creating mini solar farms out of unused rooftops.

The project will reduce electricity grid demand by an estimated 30 to 35 percent annually at each Home Depot store; the equivalent of powering 2,300 average U.S. homes for a year. The average store roof, at approximately 104,000 square feet, will accommodate 1,000 panels.

The Home Depot is working with Current, powered by GE, on 20 solar installations at stores in New Jersey, as well as eight stores in Connecticut, Maryland and Washington, DC. An additional 22 stores in California and New York will receive solar, of which six will utilize Tesla Powerpacks to store energy and dispatch additional power as needed.

"Our alternative energy projects are important elements of our sustainability and operations efforts as they reduce carbon emissions while also lowering our energy costs," said David Hawkins, vice president of labor and operations for The Home Depot.

The company's current alternative and renewable portfolio includes:

• Solar Power Purchase Agreements in Delaware and Massachusetts

• Fuel cells at more than 170 stores and distribution centers

• The Los Mirasoles Wind Farm northeast of McAllen, Texas, announced this January

• The Zopiloapan Wind Farm located in central Mexico, added this June

The solar addition will bring the company's alternative energy footprint to more than 130 megawatts (MW) as it pursues the goal of utilizing 135 MW of alternative and renewable energy by 2020.