The state advocate for utility ratepayers has called for an investigation into Green Mountain Power’s plans to expand its home energy storage program. Vermont's Department of Public Service wants to know if all customers benefit.
GMP’s program uses Powerwall batteries made by Tesla to store electricity. The power can be used during outages, and is also fed back into the grid at times of peak demand. GMP’s Kristin Kelly said about 2,000 batteries have been installed in the homes of about 1,200 customers.
She said the program saves all customers money, since the utility pays the regional grid operator based on monthly and annual peak usage. The utility has asked the Public Utility Commission to expand the program.
“So being able to offer this to more customers will be great,” she said. “And it will continue to deliver more savings to all of the customers that we serve, not just those who are in this program.”
Kelly said the Public Utility Commission in GMP’s last rate case allowed the company to spend $15 million on battery storage. She said the equipment is outperforming expectations, saving customers about $500,000 during the first 18 months of operation. GMP has about 265,000 customers, both residential and business.
“The batteries are essentially a grid resource that pays for themselves plus some,” she said.
But Dan Burke, a lawyer for the Department of Public Service, said the state wants to test that claim now that GMP wants to expand the program and implement a new tariff that would set the prices customers would pay for the Powerwalls. He said the state wants to make sure that everyone benefits.
“We're concerned that one, are the batteries actually going to work as they're intended?" he said. "We're concerned that, is GMP going to have adequate support from the batteries' manufacturer to make sure that they're functional over their useful life? And at the end of the day, we’re most concerned with ratepayers who are ultimately making the investment into these systems, that they’re getting a return on the investment that they’re making.”
The department has asked the Public Utility Commission to open an investigation into the new Powerwall tariff.
Meanwhile, Renewable Energy Vermont, a trade group representing the state's renewable energy industry, has also asked the commission to take a hard look at GMP's plan to expand the battery storage program. In comments filed with the PUC, REV Executive Director Olivia Campbell Anderson said GMP may be limiting competition and customer choice through its offering of the Tesla products.
"Innovation will come from encouraging competition in the market for energy storage, not limiting it byallocating market share to an individual vendor," Campbell wrote.
Update and clarification Sept. 5, 2019, 10:47 a.m. Post updated to include comments from Renewable Energy Vermont and to clarify that the state request for investigation is focused on GMP's proposal to expand the Powerwall program and implement a new pricing structure.