On a sunny spring day in Lee, New Hampshire, if you look closely at the town’s public library, you might see the gleam of solar panels. They’re just barely visible — a new high-tech addition to the 134-year old building that once served as a schoolhouse.
Down a creaky set of stairs in the building’s basement, surrounded by old puzzles and cooking supplies, there’s another set of shiny new objects: batteries, charged by the solar panels.
They can hold enough power to keep the library running for 48 hours. And on days when demand for electricity is high across New England, they function like a tiny power plant to help out the rest of us on the grid.
The library has an agreement with their utility company, Eversource, which allows them to tap into the batteries during times of peak electric demand. They can either put power directly into the grid, or take the whole library off the grid for a while.
It’s part of a larger effort to do something known as “demand response” or “peak shaving.” The idea is to reduce the peaks of electric demand on the grid, thereby reducing stress on the electric system and on power generators. Participating could save energy customers money. And in the long run, those efforts could help mitigate how much more infrastructure New England needs to build, as electric demand grows.
“At times the grid needs so much energy that it's better for us to attack that from the demand side, instead of just continuing to pump out more and more energy,” said Jennifer Runyon, who works on demand management for Eversource.
Runyon said that’s especially important in summer, when it’s hot outside and everyone is turning on their air conditioners at once.
“The power plants that we're using tend to get dirtier and older the more we call on them,” she said. And it gets more expensive, as higher priced generators start turning on.
“We ask our customers to reduce their demand at very specific times to help us shave that peak.”
Regional efforts to reduce demand
On June 24, 2025, as temperatures neared 100 degrees across New England, the grid experienced its highest demand day in more than a decade.
Those are the moments, Runyon says, that Eversource can tap into the batteries — like the ones at the Lee library — and smart thermostats across the region to turn down demand, coordinate energy conservation and help the grid run more efficiently. The demand they can control through demand-response programs is equivalent to roughly the amount of energy it takes to power New Hampshire’s largest city, Manchester.
Several New England utilities also have programs that use smart thermostats to manage demand.
Eversource, for example, will pay customers $50 upfront, and around $20 each summer, for the ability to tap into the controls remotely and turn the temperature up or down a few degrees to reduce energy use.
Batteries, which can have a bigger impact on energy use but can cost several thousand dollars, are more lucrative. Eversource says people with battery packs enrolled in their new demand response program could earn more than $1,000 a year, or receive upfront incentives to help with installation costs.
“If you care about the environment or if you want to make some money, I think you should participate in demand response. I really do believe it's a win-win for everybody,” Runyon said.
But there are also lower-tech ways to “shave the peak,” that don’t require a smart thermostat or battery pack. Shifting chores like laundry, running the dishwasher or charging an EV to the middle of the day (or night) when demand is lower can save money. A new law in Maine is trying to encourage that through a pilot program.
Some New England utilities also have “time-of-use” rates that offer cheaper power during times of lower demand. Some offer specific rates for customers with heat pumps or EVs.
But those rates often require customers to opt in, and there isn’t much customer participation, according to a report from Northeast Energy Efficiency Partnerships.
In Delaware, a utility with an opt-out rate has 93% customer participation, while opt-in rates for Eversource in New Hampshire and Connecticut are between 0.01% and 0.05% of customers.
Modernizing rates, the report says, could help with using the grid more efficiently. Some ways to modernize rates include upgrading the metering technology utilities use, implementing seasonal rates, and carefully-made, opt-out time-of-use rates.
Planning for the grid’s future
At a larger scale, the organization that operates New England’s grid has its own demand response tools.
Stephen George is a vice president with ISO-New England, which is in charge of keeping the region’s electricity supply and demand in balance. His team spends weeks preparing for high-demand days, when that balance gets harder to achieve.
“It's really these challenging winter and summer peaks that are what we think about and plan for the most,” he said.
On high-demand days, George’s team is coordinating with 400 power generators across New England, telling them what to do every moment of the day. An operator closely monitors the system, making changes roughly every five minutes.
If demand is high, George’s team can essentially ask big power users, like manufacturing plants, to turn off for a bit — for a price.
The New England grid has about 400 megawatts of demand response capacity, which would reduce roughly the amount of power as a medium-sized natural gas plant would be able to provide.
But demand response resources are dispatched rather infrequently. They provided only about 0.008% of the net energy needed in New England in 2025. The price for a large facility to do something like stop an assembly line is generally much higher than the price a power generator needs to run. But as energy costs climb during times of high demand, it becomes more appealing.
While the large-scale demand response market declined in 2024, George says interest in “retail” demand response — the kinds of utility programs Eversource and other utilities run – is growing.
Regional electricity use is trending up after years of decline due to energy efficiency efforts. Demand is expected to increase significantly over the next decade, along with the peaks that are hardest for the grid operators to balance. As demand grows, demand response efforts could help limit the amount of new power plants or poles and wires needed, said Jennifer Runyon.
“It’s important to realize that our grid, similar to a highway system, is built to manage the highest peak,” she said. “Every time we increase that peak, we have to build a little bit more so that we have a bigger grid. If we can keep that peak down, we don’t have to do that — we can delay that, at least.”
A tiny power plant in Lee
For the town of Lee, participating in demand response made economic sense.
The battery system cost about $33,000. But Eversource paid for half of that.
“We've had some tight budget votes in the town of Lee for the last two or three years,” said Andy Robertson, Lee’s Town Manager. “So having the ability to draw funds from the utility was key.”
Now that the solar panels and batteries are fully installed, Robertson is hoping the system can fully cover the cost of electricity for the library, which he said is the most-used public facility in town.
Plus, he said, the town will be able to rely on the library as an emergency shelter during winter storms and summer heat waves — a reliable backup, if they lose power from the grid.
The town already uses the building as a cooling center during hot days, and people come by to warm up in the winter. Historically, the public safety building has been more reliable in storms, with a larger generator. But, Robertson said, he’s excited that people will be able to come to the library to get a cup of tea, charge their phones, and maybe read a book, with power coming from the sun.
“We’re very much looking forward to this,” Robertson said. “It’s a friendlier, warmer space.”
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