The California pistachio harvest is complete for 2011, but Setton Pistachio in Terra Bella, Calif., continues to hum, processing and packaging the crop at a plant powered in large part by the same sun that nurtured the crop in the orchards.

Setton’s managers are hoping the solar power system it unveiled this summer will add some California pistachio-like green to the operation’s bottom line. And they hope this step toward going green will have a payoff for energy credits earned.

“We view this as an investment we are making by lowering our carbon footprint,” said Lee Cohen, general manager at Setton, the nation’s second largest pistachio processor.

The solar system is expected to save the company an estimated $14 million in energy costs over the next 25 years, and it could offset 1,880 metric tons of carbon emissions annually.

The system includes 7,600 modules — each weighing 44 pounds — at plants in Terra Bella and 8 miles west in Pixley, Calif. Capable of generating 1.7 megawatts of power, it’s the largest private system of its kind in the Central Valley, a place where solar systems for agricultural operations abound. Solar panels cover 7.5 acres.

Outside the Terra Bella plant, Cohen gave a tour of the installation, which includes carports on which modules are mounted, as well as ground level modules in a fenced area.

Cohen said employees welcomed the covered parking: “It’s great to be able to get into your car and not have to deal with a hot steering wheel that burns your fingers and not to have to crank up the air conditioning.”

The carports are expected to cut emissions that would otherwise result after vehicles sit under the searing San Joaquin Valley sun and drivers rush to fire up air conditioners.

The solar panels are covered with dust from the pistachio harvest and the transport of nuts into the processing plant. They’re no longer the dark blue they were in mid-July when the system was unveiled.

However, Cohen said the dust has not impaired performance of the system, something he can track on a display panel just inside the entrance to the plant. The panel is on a wall beside a rack holding Setton pistachios for display.

And it’s expected a rain or two will take much of the grime off the panels. There are also plans to possibly put micro sprinklers among the panels for periodic cleaning. Moreover, the provider of the system — as part of its contract — will do periodic “touch-free” cleaning of the modules.