South Carolina Electric & Gas Co. has received a $3.5 million grant from the federal government to offset the approximately $11.8 million it cost to install solar panels on the roof of Boeing’s final assembly building in North Charleston last year.

The money, which the utility received from the U.S. Department of the Treasury last month, is part of the 2009 stimulus package known as a 1603 payment. Because the program awards are capped at 30 percent of the total cost of qualifying renewable energy projects, it reveals, for the first time, how much the high-profile installation cost.

Bob Long, general manager of resource planning for SCE&G parent SCANA Corp., confirmed the Treasury grant, one of only a few of its kind in South Carolina, was for the Boeing project and that the $11.8 million calculation is a “fair indicator of the cost of the project.” He said receipt of the cash grant was expected since the project’s inception.

“It was part of the business case we had for Boeing,” he said Wednesday.

SCE&G owns and operates the 18,000-panel solar farm. Boeing is paying for the installation cost over the next 20 years, according to Long, but the utility will continue to own and operate the installation at the end of that period.

The grant, which SCE&G applied for in January and which Treasury documents show was paid April 14, will count against the aerospace company’s debt. A Boeing spokeswoman deferred questions about the arrangement and the grant to SCE&G.

Long said there will be no impact on the utility’s ratepayers.

Paul Messerschmidt, a Mount Pleasant-based energy consultant, called the arrangement “a great model that should be repeated.”

“If it’s good enough for Boeing, it’s good enough for all the other businesses in SCE&G territory,” said Messerschmidt, who heads the Energy Innovations Group.

“That’s exactly the role that utilities should be playing,” he said.

The 2.6-megawatt installation, which went live late last year, is one of the largest in the United States.

Boeing South Carolina gets up to 20 percent of its energy from the roof of the massive final assembly building and has won several awards for its commitment to getting 100 percent of its energy from renewable sources.

However, the manufacturer of the panels, Michigan-based Energy Conversion Devices and its subsidiary United Solar Ovonic, filed for bankruptcy in February. That case remains unresolved, but Long reiterated Wednesday that he is not concerned about warranties.

The 1603 program covers certain alternative energy installations on which construction began or that went live from 2009 through 2011.

As of May 9, there were comparatively few awards of funding to South Carolina companies.

The SCE&G award was the largest of seven solar electricity grants and second to a Duke Energy Carolinas hydropower project overall. The others were four fuel cell projects, four solar thermal projects, a small wind project and a geothermal project.

“The South Carolina list was really small,” said Messerschmidt, who recently moved to the Lowcountry from Florida. “There wasn’t a lot of large-scale stuff.”

Long agrees there’s room for growth based on the success of the Boeing project.

“I think it sets a standard,” he said. “Others look at Boeing and say, ‘It was possible for you. Can we do the same?’ ”

“We want to help our customers achieve their objectives,” Long said.

Reach Brendan Kearney at 937-5906 or kearney_brendan@twitter.com.