Tennessee's biggest health insurer is turning to the sun to power its corporate headquarters atop Cameron Hill in Chattanooga.

BlueCross BlueShield of Tennessee plans to start installing the first of about 10,000 solar panels next month on top of the company's five major office and parking facilities at its Chattanooga headquarters. The $10 million project will be capable of generating 4.3 megawatts of electricity and will be the second biggest solar array in Chattanooga — behind only the $30 million solar farm installed at the Volkswagen assembly plant in 2012 to generate up to 9.5 megawatts of electricity.

BlueCross officials said Wednesday the solar panels will help reduce the company's carbon footprint and, at times, should be sufficient to generate all of the energy needs for the company's main office. But beyond the environmental reasons, BlueCross said the declining costs and improved efficiency of solar panels, combined with the 30 percent federal investment tax credit for solar installations this year, make solar generation cheaper than purchased electricity.

"We expect to save $23 million in energy costs over the projected useful (25-year) life of the solar equipment," said John Giblin, executive vice president and chief financial officer for BlueCross. "This long-term return on investment will help us lower operating costs and deliver better value for our members over time."

In 2011, BlueCross installed a solar installation on the roof of its Gateway office complex off of West M.L. King Boulevard using a federal grant program that is no longer available. That solar facility is capable of generating only 198 kilowatts of electricity, or near the capacity of the grant money at that time.

The solar project being installed this spring and summer at BlueCross won't get any federal grants, but it will be more than 20 times bigger and should be more energy efficient.

Jeff Sundean, vice president of property and corporate services for BlueCross, said the company has looked at solar power options for some time, but when the $300 million Cameron Hill complex was erected a decade ago, the economics of solar generation were not as favorable.

"With the advancement of solar technology and the reduction in costs of solar equipment, we just felt like now is the time to undertake this bigger project," Sundean said.

On average, solar will offset around 25 percent of our overall energy needs for the Cameron Hill and Gateway facilities where about 3,600 of the entire 6,000 employees at BlueCross work.

"When these solar panels are generating at peak levels during some times of the day, they will 100 percent offset our energy use," Sundean said. "We will saturate the roofs of all five of our office buildings (in Chattanooga) with these panels."

When completed by the end of June, the new solar array is expected to reduce BlueCross's carbon emissions equal to the amount of carbon stored in 5,000 acres of trees and save the energy equivalent of 400,000 gallons of gasoline per year.

BlueCross also has a small solar energy facility at its Memphis office, Sundean said. In addition to the solar power being added to its buildings, BlueCross also has achieved gold or platinum LEED (Leadership in Energy and Environmental Design) certification from the U.S. Green Building Council for all of its offices across Tennessee.

When it opened in June 2009, the BlueCross corporate headquarters was the second biggest corporate campus in America to achieve gold LEED status for its energy efficiency.

The additional solar generation by BlueCross this year is part of what experts expect will be another year of growth in power generation from the sun. Last year, the Solar Energy Industry Association (SEIA) estimates 10.6 gigawatts of solar PV capacity was added in the United States — up 2 percent from the previous year and enough power for 12.3 million homes.

Wood Mackenzie, an energy research and consulting firm, forecasts 14 percent growth in solar installations this year to more than 12 gigawatts and the SEIA predicts total installed U.S. solar generating capacity will double over the next five years.

Contact Dave Flessner at dflessner@timesfreepress.com or at 757-6340