A Green Mountain Power proposed tariff filing offers state utility regulators the opportunity to conduct a detailed review of the financial costs and benefits of residential-scale battery storage and determine whether GMP’s proposed pricing structure appropriately balances risk for non-participating ratepayers, the Vermont Department of Public Service recently said.
The Vermont Department of Public Service recently said that it is concerned that Green Mountain Power’s (GMP) battery storage programs may be placing a disproportionate share of financial risk on non-participating ratepayers and that a GMP proposed tariff filing “provides an opportunity to conduct a detailed review of the financial costs and benefits of residential-scale battery storage.”
On Aug. 1, Green Mountain Power filed a pilot energy storage tariff for an extension of its original battery storage incentive program with the Vermont Public Utility Commission.
Under the program, the tariff will be offered for up to 5 MW of installed capacity per year and is open to Green Mountain Power residential customers and small commercial customers that do not participate in the utility’s time-of-use tariff. That translates to about 500 customers per year.
Also, Green Mountain Power customers would lease an energy storage system owned by the utility. Customers can choose to pay a monthly lease charge of $55 for 10 years or an upfront one-time lease payment of $5,500 per storage system. In the filing, Green Mountain Power called the new program “a new, innovative way to treat localized, distributed grid services.”
In addition to the backup power the storage systems can provide to customers, Green Mountain Power retains the option to discharge the storage systems to manage its peak load, for example to shave peak loads in order to avoid the purchase of costly peak energy supplies.
In a Sept. 3 filing with the Vermont PUC, the DPS notes that GMP currently provides customers with access to Tesla Powerwall systems for residential battery storage through several different ongoing innovative pilot programs, which are authorized under GMP’s current and most recent alternative regulation plans.
The DPS is housed within the executive branch of Vermont state government and is charged with representing the public interest in energy, telecommunications, water and wastewater utility matters.
The DPS said it previously raised concerns regarding the costs and benefits of GMP’s battery storage pilots both during GMP’s most recent traditional rate case and in response to two separate innovative pilot filings that included Tesla Powerwall Systems.
“While the Department has acknowledged the potential benefits of small-scale battery storage, the Department has maintained that GMP’s battery-storage offerings may be placing a disproportionate share of financial risk on non-participating ratepayers,” the DPS said.
The DPS has also recommended that GMP’s battery storage programs be subject to detailed financial review as a standalone tariff filing before the Commission to determine whether continuing expansion of these programs will promote ratepayers’ best interests.
“GMP’s proposed tariff filing provides an opportunity to conduct a detailed review of the financial costs and benefits of residential-scale battery storage and determine whether GMP’s proposed pricing structure appropriately balances risk for non-participating ratepayers,” the DPS said.
It therefore recommended that the Commission issue an order that suspends and opens an investigation into GMP’s proposed Energy Storage System tariff and sets a date for an initial scheduling conference.
“We welcome and fully expected this review of our new filing, as this is a standard procedural request,” Green Mountain Power spokeswoman Kristin Kelly said. “All our programs are designed to provide direct benefits to the participant but also have to provide benefits to all the customers we serve or we wouldn’t be doing it as we are laser focused on driving down costs and carbon.”
In its first 18 months, Green Mountain Power’s original energy storage incentive program saved all Green Mountain power customers $500,000 above and beyond the costs of the program, Kelly said.
Green Mountain Power in 2015 became the first utility in the country to team up with Tesla to offer incentives for customers to install home battery storage units. That program, which is now closed, supported the installation of 2,000 batteries and is projected to save $2 million for all Green Mountain Power customers over the program’s 10-year life.
Green Mountain Power has since introduced other energy storage pilot incentive programs, such as Bring Your Own Device (BOYD) program, and its Resilient Home program launched this spring that some customers to combine a home backup battery system with the functions of an advanced meter. Both of those programs were covered under a blanket authorization in previously approved rate cases.
The BOYD program closed Sept. 10, and all the slots are already full for the Resilient Home program.