Vermont electricity providers are searching for ways to capture solar energy when the sun is setting.
Vermont Electric Co-op is planning a 5-megawatt solar project that aims to capture solar energy at dusk. Unlike many solar projects that face south to catch the afternoon sun, the co-op will orient a group of panels toward the west to catch energy later in the day.
Williston manufacturer AllEarth Renewables has developed “solar trackers” that pivot to follow the sun throughout the day. But this technology may not fit the co-op’s budget for the proposed project.
David Hallquist, CEO of VEC, said the purpose of the solar project is to take advantage of the economies of scale through a national partnership with a cooperative network.
He said it costs less to build extra panels that face the setting sun than to install solar trackers. His last estimate found solar trackers cost about 30 percent more than traditional panels, not including the additional maintenance and operating costs.
Hallquist plans to build 35 percent more solar panels than is needed for output.
“The cost of panels is so cheap that you can now afford to add more solar panels than you need,” he said.
The co-op’s board approved the budget for the project this week and Hallquist said the co-op is still considering four sites for the project in the western section of its service area. VEC will select two sites to divide the project.
Green Mountain Power, the state’s largest utility that is leading an effort to turn Rutland into Vermont’s solar capital, is looking at ways to store solar energy that can be consumed later in the day.
The company is building a solar project that will include a combination of lead and lithium ion battery storage containers. Last week, state regulators approved GMP’s 2.5-megawatt solar project known as the Stafford Hill Solar Farm, which is located on a 15-acre closed landfill.
The net price of the storage component of the project will cost ratepayers more than $4 million, according to the company’s certificate of public good. The company estimates the value of the storage component at between $2.8 million and $6 million.
Shifting Peak
Vermont utilities place a high value on solar energy because the output aligns with peak demand — a time when utilities must otherwise purchase expensive power generated from fossil fuels.
The state’s peak power consumption begins in the early afternoon when air conditioners are turned on. While solar power can be used to offset this electricity consumption, solar output drops off faster than demand because air conditioners continue to run beyond sunset.
For this reason, the state’s peak power demand will at some point occur when solar generation is unavailable.
Bob Amelang is a retired power system planner and engineer with Green Mountain Power. He said this shift in the state’s peak power consumption could impact the value solar offers as a peak-load reducer.
“When one looks at the advantage of solar in Vermont, its value is diminishing,” Amelang said. However, he said more penetration of solar is needed before utilities will have to re-evaluate the price they pay for solar.
GMP spokeswoman Dorothy Schnure said the company estimates the shift to occur in “a handful of years.” And at this point, she said “new solar may have a different cost-benefit analysis,” pointing out other factors that may drive down the cost to install solar as well.
Darren Springer is deputy commissioner for the Department of Public Service. He said state’s new net-metering program will allow utilities to place an appropriate value on solar as more projects come online.
If solar is unavailable to shave the state’s peak demands in certain areas of the state, he said the program could be designed to incentivize other renewable technologies.
“You might find in that instance that a net-metered wind project may have more value in that region than solar and you might price it appropriately,” he said.
