GMP’s Growing Stored Energy Network Delivers $6M in Savings During July Heat Wave and Provides Lasting Year-Round Benefits for Customers

COLCHESTER, Vt. – Green Mountain Power’s (GMP) virtual power plant (VPP) of clean, stored energy has significantly driven down peak energy costs by approximately $6 million for all GMP customers during early July’s extreme heat event. During these multi-day or prolonged periods of extreme heat, energy use soars as cooling needs increase, and the result is skyrocketing prices as well as increased need for peaker plants or ancillary power sources, which are often dirtier and far more carbon intensive. In partnership with customers, GMP was able to deploy 90 MW of carbon-free stored energy from residential energy storage systems and utility-scale batteries. That is the equivalent of taking 50,000 homes off the grid during this time. This proven strategy builds on the $11 million saved for customers last year.

“This energy strategy reflects what’s possible when we innovate in partnership with our customers and the communities we serve,” said GMP President and CEO Mari McClure, “Energy storage is a cornerstone of a cleaner, more resilient and more affordable electric system that lowers costs, strengthens reliability and gives customers greater control over how they use and manage energy. We are grateful for the thousands of customers who are part of helping us build this smarter, more flexible grid, delivering significant benefits today and creating a stronger energy future for everyone.” 

GMP’s network of energy storage is used as what is called a virtual power plant (VPP), supplying clean stored energy at key times to reduce energy demands during peak events such as during the extreme heat experienced across Vermont in early July. At 110MW this VPP now has the distinction of being Vermont’s largest energy source. 

Residential batteries in customers’ homes make up the largest component of GMP’s VPP with more than 5,000 customers and more than 10,000 batteries in the program with demand growing each year. GMP was the first utility in the country to offer a fully tariffed, state-approved home energy storage lease program for seamless backup power at home. 

“We absolutely love our energy storage through Green Mountain Power. It is seamless, noiseless and very affordable. Sometimes the only way we know the power is out because we hear our neighbor’s generator humming across the property,” said GMP customer Pollyanna Bladyka, who has stayed connected through microbursts and other damaging storms multiple times since joining the energy storage lease program. “It is reassuring and keeps us comfortable at home, and we also love how the program is reducing power costs for all GMP customers, too.”

The popularity of residential energy storage along with all storage across GMP’s service area hit an exciting peak of its own this year, with stored energy now able to meet nearly 10% of Vermont’s summer peak, the highest storage-to-state-peak ratio in New England.

Because GMP’s VPP has demonstrated such quick and reliable response during peak events, and residential battery enrollment continues growing across the service area, GMP has been able to permanently close two peaker plants in the last few years – in Vergennes and Rutland – through a rigorous ISO-NE retirement process. Peaker plants are quick-responding resources that supply steady power during regional grid events, so ISO-NE requires this thorough review to ensure the grid stays safe and reliable as they retire. As GMP’s stored energy network grows, the company plans to close more peaker plants.

More about GMP’s growing VPP

As of July 2026, GMP’s virtual power plant is 110 MW and it is made up of a combination of energy resources which GMP can call on at any time to respond to grid needs to reduce costs for customers. More than 50% of the VPP is through residential energy storage systems in GMP programs in partnership with GMP customers. The next largest portion is utility-scale energy storage systems. The VPP also includes other dispatchable resources such as electric vehicle chargers, commercial buildings that act like batteries through GMP’s Flexible Load Management program, and hydro power plants.

More about GMP’s residential energy storage programs

More about GMP’s energy storage lease program is here and GMP’s Bring Your Own Device (BYOD) program is here.

About Green Mountain Power

Green Mountain Power serves more than 275,000 residential and business customers in Vermont with electricity that’s 100% carbon free on an annual basis. GMP is partnering with customers to provide solutions that deliver resiliency while cutting carbon and costs for all. GMP is the first utility in the world to get a B Corp certification, meeting rigorous social, environmental, accountability and transparency standards and using business as a force for good. GMP was named to Fast Company’s 2024 Most Innovative Companies in the World list, the sixth time earning that honor. In 2024, 2023 and 2021 the Smart Electric Power Alliance (SEPA) honored GMP as a nationwide leader in energy transformation. And, in 2022 GMP was named to TIME’s list of the 100 Most Influential Companies for its groundbreaking resiliency work to transform the grid for customers. 

This energy strategy reflects what’s possible when we innovate in partnership with our customers and the communities we serve.

Mari McClure, GMP President and CEO