Could Backup Power Solve Outage Problems?

CHATHAM – In 2022, according to data collected by state regulators, Chatham experienced 44 power outages, affecting 20,964 homes. On average, Chatham customers were without electrical service for 14.7 hours that year.

“Chatham is officially the third worst of all the towns in the state,” said Mike Spiro of Nexamp, the Boston-based community solar developer. Spiro spoke to the town’s energy and climate action committee last week to discuss the potential use of residential battery systems to help bolster the town’s power infrastructure.

Committee member Brian Miner invited Spiro to present to the committee to discuss a pilot program Nexamp is running in Newburyport, Mass.

“They’ve been a leader, as a seashore community with a bit of a sketchy grid,” Miner said. The Cape Light Compact has already begun preliminary talks with Nexamp to discuss the idea.

Nexamp is focused on community solar farms, many of which are equipped with large storage batteries. On sunny days, the solar panels generate more electricity than the grid can absorb at once, “so essentially the batteries are storing that excess energy, and then later in the day when it gets cloudy or when the sun goes down, that’s when we’ll export that excess energy that we are storing,” Spiro said. While the grid is rich with renewable energy in the daytime, it relies on traditional power plants to meet the need once the sun goes down.

On hot summer evenings when people return home from work and turn on air conditioners and appliances, the operator of the regional grid calls up fossil fuel power plants and having them increase output to prevent brownouts and blackouts. “And those are really expensive phone calls ... to make, not to mention sort of a step in the wrong direction in terms of their climate goals,” Spiro said.

Nexamp is now exploring the idea of encouraging the use of residential batteries, working together as a unit, to reduce demand on a community’s electrical grid in times of stress.

“Just like a generator, if you were to lose power, the battery would automatically switch over to powering your house for as long as either it lasted or until the power came back on,” he said. The arrangement is good for individual customers who enjoy backup power, and for utilities, which can use it to lower the cost of meeting peak demand. Nexamp also profits by being compensated by the utilities for operating the system.

Portable generators for a household cost a couple thousand dollars, and automatic standby generators run around $15,000, Spiro said. “Generally these batteries are even more expensive than that; they’re around $25,000,” he said. “Most homeowners don’t have $25,000 lying around.” Under the model proposed by Nexamp, the company would own the batteries, but would make them available to homeowners for around $6,000. “We’re just going to keep it in your house and give you some of the benefit, with backup power,” he said.

Nexamp would then remotely operate all of the residential batteries, selecting when to have them feed excess power to the grid at the optimal time. Operated as a single unit, along with other high-tech devices like smart thermostats and smart electric vehicle chargers, the residential batteries create a virtual power plant that can support the grid at times of peak usage, Spiro said.

Under the proposal, Nexamp would receive payment from the utilities for operating the virtual power plant, and would use some of that revenue to reduce the cost of backup batteries for consumers.

Sometimes installed as part of a residential solar system, batteries can be owned by the property owner, who theoretically gets to control when the battery feeds the grid and when it retains power for an emergency. Under the Nexamp proposal, the company would own the batteries and would make that decision.

One committee member asked what guarantee a homeowner would have that a residential battery owned by Nexamp would actually be fully charged when it’s needed for backup power.

“That’s definitely one of the downsides here,” Spiro said. Generally speaking, most power outages in places like Chatham happen in the winter during storms that bring ice, snow and winds, while the peak demand that utilities care about “are generally more in the summer. So there tends to be low overlap,” he said. But it’s possible that, in a very unlucky scenario around 9 p.m. on a hot summer night, “you might have just finished draining your battery to help the utilities, and then a car drives into a telephone pole on your street and knocks out power. In that case, your battery would be empty and wouldn’t be able to supply you with backup power,” he said.

The pilot program in Newburyport aims to answer various questions about the proposed system, including how often conflicts like that actually happen.

“That’s one of the things we’re hoping to learn,” Spiro said.

Another committee member noted that the next generation of electric vehicles will likely have the capability to provide backup power for the owners’ homes, but Spiro said that arrangement isn’t ideal.

“You could be in a situation where you have backup power but then you have a dead car in your driveway,” he said.

Miner thanked Spiro for his presentation. When it comes to improving the reliability of electrical service in Chatham, Eversource has pledged to add an additional feeder line from Harwich in the years ahead, he noted.

“That’s one piece of the solution,” Miner said, and solar installations, batteries and other technologies will likely provide the other pieces. “This fits in,” he said.

* This article has been changed to clarify that, in times of peak demand, the regional grid operator, not the utility companies themselves, calls up additional power from fossil fuel generating plants.