Powering Strong Communities

Program uses network of residential storage batteries to help balance New England grid

A new program from Vermont-based Green Mountain Power (GMP) marks the first time that stored energy in a network of residential batteries is being used to help keep the regional grid balanced, GMP said on May 13.

GMP’s new frequency regulation pilot program allows customers to share stored energy with regional grid operator ISO New England (ISO-NE) to keep a steady, regulated flow of energy on the grid at all times, a critical function for regional system safety and reliability for customers, GMP said.

It noted that ISO-NE is continually calling on qualified regional energy producers to increase or decrease output to help maintain that important balanced flow of power on the grid at all times. Typically, this cycling on and off of energy is done by ISO-NE with fossil fuel generators through the regulation market, a wholesale energy market that also pays participants for their consistent, quick, and accurate responses to grid needs, which can shift minute-to-minute.

Using their network of Powerwall batteries and Tesla Autobidder software, GMP is the first utility to perform this key grid service in the wholesale power market with stored energy distributed from customers’ homes.  The project is also benefitting all GMP customers through reduced power supply costs, according to GMP. It creates a new value stream for all GMP customers in addition to the ongoing benefits of GMP’s earlier home energy storage programs, GMP said.

GMP successfully entered the regulation market with this network of residential power sources after three months of testing with ISO-NE, and partnerships with ISO-NE, Tesla and Customized Energy Solutions (CES), a software solutions company. Tesla coordinates the distributed batteries to respond to signals from ISO-NE and aggregates critical data about the response, while CES provides the key integrations between Tesla and ISO-NE.

A total of 200 GMP customers are currently enrolled in the program and a prerequisite is that they already have two Powerwall batteries through a GMP program.

GMP plans to expand this pilot program in the future. Customers sharing energy through the program are paid $13.50 per month on their energy statements. This includes a share for their program participation and for the increased use of their batteries, which can charge and discharge rapidly for periods of time each month.

GMP takes steps to ensure that customers have backup power available if weather is predicted to cause outages.

In 2017, GMP was the first utility to partner with Tesla, and launched the first Powerwall pilot program.

GMP is now the first utility with tariffed home energy storage programs for customers. These programs provide participating customers with backup power in residential batteries in exchange for sharing some of that stored energy to reduce peak demand on the grid.

There are about 3,000 Powerwalls installed in customers’ homes, and GMP’s network of stored energy, including Powerwalls, car chargers, and utility-scale batteries, helped reduce costs for customers by more than $3 million in 2020 through peak reduction, according to GMP.

GMP serves approximately 266,000 residential and business customers in Vermont.