Vermont turns thousands of home batteries into a virtual power plant

Spread across thousands of ordinary homes, a network of batteries has become Vermont's largest power source, providing households with backup electricity while helping the state utility reduce its reliance on conventional power plants.

More than 5,500 people in Vermont have home battery systems through a programme run by Green Mountain Power (GMP), the state's largest utility. The batteries are connected through software to form what is known as a virtual power plant.

The BBC reported that GMP's programme provides about 110 megawatts of power, making it the largest power source in Vermont. The programme allows the utility to draw on customers' batteries when needed, while customers retain reserve power for their own use, particularly during outages.

For Pollyanna Bladyka, who lives in rural Springfield, frequent power cuts prompted her to consider buying a gas generator in 2024. Instead, an electrician told her about GMP's battery programme, which provides two batteries for $55 a month under a 10-year lease.

Bladyka and her husband chose the batteries over the $12,000 generator they had planned to buy. She said they have not experienced a power outage since the system was installed in 2024.

"I'd like to say I did it for the environment, but I did it for myself," Bladyka told the BBC. "But I don't mind helping."

Vermont has experienced an increase in extreme weather and power outages in recent decades, with flooding, snowstorms and other severe weather events affecting the state.

GMP said seven of the 10 most damaging storms in its history occurred during the past decade, causing more than $225 million in damage.

The utility says its battery programme can provide Bladyka's home with electricity for up to two days if electricity use is kept to a minimum.

Virtual power plants combine thousands or even millions of consumer energy devices, including home batteries, rooftop solar panels, smart thermostats and electric vehicle batteries, into a coordinated system that can support the wider electricity grid.

Rather than generating electricity like a conventional power plant, virtual power plants use software to manage demand and distribute stored or generated energy when it is most needed.

The concept has gained momentum in recent years as electricity demand has increased and more distributed energy resources have been connected to the grid. 

According to Wood Mackenzie analysis cited by the BBC, the US currently has more than 40GW of virtual power plant capacity.

A 2025 US Department of Energy report estimated that up to 160GW of capacity could be unlocked by 2030, equivalent to around 20% of the country's expected peak electricity demand.

GMP's programme began as a pilot in 2017 and has expanded significantly since regulators lifted a cap on enrolment in 2023. More than 2,500 customers have joined the programme since then, according to the utility.

The programme effectively replaces some of the need for fossil-fuel-powered peaker plants, which utilities traditionally use to meet short periods of exceptionally high electricity demand.

GMP previously relied on oil, diesel and natural gas plants for peak demand. Chief Executive Mari McClure said the utility has gradually decommissioned some of those plants as they reached the end of their operational lives.

Four peaking plants remain available for occasional use when required by the New England regional grid operator, according to GMP.

The utility says its virtual power plant saved customers $11 million last year. The US Department of Energy has estimated that virtual power plants could save the country more than $10 billion annually by 2030.

Kate Peters, a virtual power plant expert at consultancy The Brattle Group, said GMP's programme could be one of the largest battery programmes in the US.

GMP serves more than 75% of Vermont and has set a goal of eliminating power outages by 2030. It is also considering providing batteries at no cost to thousands of customers in rural and outage-prone areas.

The utility aims to offer energy storage to all of its nearly 300,000 customers who want it and more than double the size of its virtual power plant by 2034.

It also plans to explore using Vermont's electric vehicle batteries as a distributed energy resource through vehicle-to-grid technology.

Despite the potential, virtual power plants face challenges, including the cost of enrolling customers and integrating distributed resources into wholesale electricity markets.

Jen Downing, a former US Department of Energy official, said utilities often have limited financial incentives to use demand flexibility because traditional infrastructure investments can be more profitable for them.

However, states including Massachusetts, Illinois and New Jersey are encouraging utilities to procure capacity from virtual power plants as they seek to reduce energy costs.

As utilities look for ways to meet growing electricity demand without building more conventional power plants, Vermont's experience is emerging as an example of how homes and their energy systems can become part of the wider power grid.