From left: Chen Xin and David Zhang watch as Sam Poutasse of Depot Road purchases peaches during Carlson Orchards’ Peach Festival Aug. 20. (Photos by Lisa Aciukewicz)

Newell Thomas (right) of Lighthouse Electrical gives a tour and an explanation of the  solar array at Carlson Orchards.

Against the backdrop of its annual Peach Festival last weekend, Carlson Orchards celebrated the success of its solar array, installed a year ago. Since last August, when the switch was thrown, the array, made up of 1,050 photovoltaic panels, has produced around 80 percent of the farm's energy needs, far exceeding its owners' expectations.

The array produced its first 267,000 kilowatt hours, a 52-week forecast, ahead of schedule, according to Symantha Gates of EC3 Consulting, the green technology project manager hired by Carlson to obtain the grant money that largely funded this project.

Newell Thomas, the electrician from Lighthouse Electrical Contracting who directed the installation of the solar array, was on hand last weekend to explain how it "spins the meter backwards." He pointed out that the energy the array generates does not go directly to the farm but into the electrical grid. The farm account with utility company National Grid is credited with the value of the energy it produces. This is known as virtual net metering.

With typical solar installations, the customer uses the energy first, and the excess ("net metered") is sent to the grid. The Solarize Harvard project has proposed a neighborhood net metering structure, which allows solar production to be distributed to multiple meters in Harvard.

As reported by the Press last April, Carlson Orchards, a medium-sized orchard producing fruit for wholesale markets, was looking for a way to remain competitive and needed to reduce its cost of production in order to become more sustainable. According to company numbers, the orchard, on Oak Hill Road, produces 60,000 bushels of apples, 5,000 baskets of peaches and nectarines, and more than 500,000 gallons of apple cider annually. Adding significantly to the cost of growing and harvesting the fruit, Carlson says, is the cost of keeping fruit in a state of suspended animation in controlled atmosphere rooms.

In 2010, the "carbon footprint" for this farm's energy consumption was about 400,000 kilowatt hours per year, at a cost of about $85,000.

Just four months after the Press reported on the project's approval, the system was staged, installed and connected. Where there once existed a stand of old apple trees in winter, now stands a state-of-the-art photovoltaic solar array that is the largest existing on a farm in Massachusetts.

Last August, the Press reported on a ribbon cutting ceremony attended by several lawmakers, state and federal officials, and nonprofit organizations that helped with the project. Owner Frank Carlson said then, "It will take a year to know exactly how much it will provide."

A year later, the data is in, and cost of electricity to the farm has been reduced by at least $50,000 annually, Thomas said.

Before installing the solar array, the farm was using the energy equivalent of 33 average homes per year, Gates said last year; that is now reduced to less than 10 homes.

"Taking that much off the grid means less coal burned, which leads to less greenhouse gas emissions," Gates said.

Before going solar, the farm produced the equivalent of the greenhouse gas emissions from 38 passenger vehicles per year, or 21,570 gallons of gas. That's more than 2.6 tanker trucks-worth of gasoline, Gates said.

"It is the amount of carbon sequestered annually by over 40 acres of pine or fir forests," she said.

Gates is continuing onboard at Carlson, providing mandatory feedback reports for the government grants the farm received.

Asked if there were any startup problems or challenges after the switch was thrown, any glitches or downtime, Frank Carlson said last weekend there were no problems at all, and the system has remained fully functional at all times. In fact, the only problem was that the server for the educational monitor in the store had been down for a few days.

"It's been a good year," he said.