Green Mountain Power uses Tesla Power Walls to beat the peak


Green Mountain Power’s commitment to innovation delivered bigger savings to customers as New England recently hit a new yearly peak for power demand.

GMP’s growing network of stored energy reduced demand on the grid as temperatures soared and offset more than $600,000 in costs for customers. That’s $100,000 more than during the earlier ISO-NE peak set on July 5.

“Our growing network of stored energy is what’s delivering unique savings to customers,” said Josh Castonguay, GMP vice president and chief innovation officer. “Our system worked seamlessly to drive down demand at the key moment it needed to, which translates into savings for customers. This is what our new energy future looks like, delivering on innovations, while finding ways to cut costs and carbon.”

There are now more than 610 Tesla Powerwall batteries in customers’ homes, providing backup power like a generator, but with lower carbon. As part of an innovative approach to cutting costs for all customers, GMP offers the batteries for just $15 per month. Customers get convenient power backup they can charge with their own solar or off the grid, while GMP can share access with that stored energy during peak demand times.

About 500 Powerwalls were in customers’ homes during the July heatwave when GMP first demonstrated that stored energy in its network of Powerwalls and community storage with solar installations in Rutland and Panton, could cut costs and carbon for customers. The July peak offset more than $500,000 in costs for customers. This new peak replaces those savings, and delivers even more – $600,000.

Castonguay says the amount of stored energy deployed to beat the new peak last week was like taking up to 6,000 homes off the grid and it offset about 21,120 pounds of carbon, the equivalent of not burning 1,078 gallons of gasoline.

“Years of looking ahead and proactive work is continuing to pay off for all of our customers,” Castonguay said. “Innovation like storage is key to how we are going to transform the grid to one that is more home-, business-, and community-based and do it in a cost-effective way.”

According to ISO-NE, regional power demand hit its peak for the year between 5 p.m. and 6 p.m. Aug. 6, surpassing the previous peak set July 5. ISO-NE uses the yearly peak hour to calculate costs utilities pay toward the regional grid, so when utilities are able to lower demand during that key hour, they can create savings for customers.

GMP plans to continue to track demand and the weather and be ready to deploy its growing network of stored energy in case there is another regional peak during 2018. GMP also uses its stored energy network to deliver savings by beating monthly statewide peaks, which are also used to set other grid costs.