Five solar projects sprouting along the Massachusetts Turnpike and Route 3 are not the largest in the state, but they are among the most visible and striking examples of a solar industry that has grown more rapidly than most policy makers and energy specialists ever imagined.
As tens of thousands of commuters whiz by, the gleaming rows of solar panels in locations like the Interstate 90 service plaza in Framingham, an embankment on the turnpike near Natick, or a rest area on Route 3 in Plymouth show how solar power has been integrated into daily life. The Framingham and Natick projects are already generating power; when the other sites in Framingham and Plymouth become operational later this month, the five solar farms will produce a combined 2,500 kilowatts of electricity, enough to power about 500 homes.
The highway solar farms are part of an initiative launched two years ago by the state Department of Transportation that will build at least 10 solar projects on unused department property, eight of them along the Mass Pike. The remaining solar farms will be built next year near Stockbridge and in Salisbury off of Interstate 95.
Ameresco Inc. in Framingham, a publicly traded energy management and procurement company, is developing the solar projects under a contract that pays the DOT nearly $100,000 a year in land leases and allows it to buy electricity at reduced rates from Ameresco. The lower power costs could save the state $15 million over 20 years.
Ameresco, which is investing at least $12 million in the solar project, is allowed to sell excess power to electric utilities at a profit.
"It's a win-win situation for both," said Hongyan Oliver, a renewable energy analyst and project manager at the transportation department. "The more electricity produced, the more money we save, and the more they make."
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The highway solar projects are part of a wider push by the state to expand the use of renewable energy to generate electricity. Before the Green Communities Act, which set out ambitious goals to cut carbon pollution and boost wind, solar, and other clean-energy technologies, was passed in 2008, Massachusetts had only about 3 megawatts of solar-power capacity across the state. Today, the state's solar capacity stands at 903 megawatts, or enough electricity to power about 137,500 homes, according to state data.
The state's solar push has been so successful that developers have already hit the caps on the amount of electricity that utilities must buy from solar producers. Last month, the Baker administration filed legislation to lift those solar caps. The long-term goal: producing 1,600 megawatts of solar-generated electricity by 2020, or enough to power about 240,000 homes.
To date, the largest solar farms in Massachusetts — in Billerica, Carver, Chester, and Dartmouth — can each produce a maximum of nearly 6,000 kilowatts of electricity. By comparison, the largest of the current and planned Ameresco projects — in Framingham, Salisbury and Stockbridge — will generate about 650 kilowatts.
But the combined capacity of the 10 sites is about 5,500 kilowatts, making this public-private partnership a big deal in the renewable energy industry.
In Framingham, there are two solar farms on either side of the Pike's Exit 13, each containing 2,100 panels installed on metal ramps. Typically, each solar site has one or more inverters, to convert power from direct current to alternative current, and a transformer, to adjust voltage so power can be sent across the region's electric grid.
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Founded in 2000, Ameresco initially positioned itself as an energy management and efficiency firm whose involvement in the renewable energy market was limited to biogas: methane reclaimed from landfills and sewage treatment plants that is used to generate electricity or fuel for industrial boilers. But over the past five years or so, the company has pushed aggressively into other renewable energy fields, particularly solar power.
Today, 25 to 30 percent of Ameresco's more than $600 million in annual revenue comes from its renewable energy businesses. The company employs more than 1,000 people.
"The acceptance of solar and the penetration into the market has really accelerated in recent years," said Joe DeManche, an executive vice president at Ameresco. "There are all types of solar customers now: residential, government, and commercial."
Jay Fitzgerald can be reached at jayfitzmedia@gmail.com.