"In total, those plants use about 66% of the total electricity consumed by city of Fayetteville government operations," says Peter Nierengarten, Fayetteville's environmental director.

So he says the project takes the city a long way toward meeting its goal of powering all city facilities with renewable energy by 2030.

And it saves money because the city buys the solar power at a rate slightly lower than what it paid for electricity from the utility.

"It just made really good economic sense for us," Nierengarten says. "It made good energy sense for us. It made good political sense for us."

He encourages other cities to switch to renewables.

"It's not that difficult," he says. "The price of renewables, particularly solar, has come way down. These types of projects are very accessible and … with the right partner, very doable."