Dive Brief:
- ES Solar has sold 18 MWh of sonnen home energy storage systems in Utah through the Go Back battery retrofit initiative of Rocky Mountain Power’s Wattsmart virtual power plant program, representing over 75% of ES Solar’s 2024 sales, the companies said Sept. 5.
- ES Solar aims to retrofit about 32,000 Utah customers with sonnen batteries over the next five years, firming about 40% of the state’s approximately 80,000 solar-only residential PV systems, the companies said.
- “ES Solar has established a new, replicable business model and sales marketing strategy [to enable] grid-interactive and responsive solar that supports, rather than becomes a nuisance to the energy grid,” sonnen USA Chairman and CEO Blake Richetta said in a statement.
Dive Insight:
Rocky Mountain Power customers who installed solar PV systems before Sept. 1, 2021, may qualify for a $600/kW incentive when they add a home battery system and enroll in Wattsmart, compared with a $400/kW incentive for newly installed solar-plus-storage systems, the companies said.
The early success of the partnership between sonnen and ES Solar highlights the significant potential of home energy storage retrofits and a path forward for solar installers “beyond the ‘dead-end’ of typical solar net-metering [frameworks],” Richetta told Utility Dive in an email.
State regulators and policymakers are pushing back on traditional net metering, most notably in California, where regulators in 2022 approved a net billing framework that disincentivizes solar-only PV systems.
Despite relatively low retail electricity costs, Utah customers are interested in battery retrofits to guard against future rate increases and more frequent outages, said Nate Walkingshaw, founder and CEO of Torus. The Utah-based, vertically integrated distributed energy resource provider that sells solar, storage and home energy management systems in Rocky Mountain Power territory.
Utah PV customers are also being swayed by the increasingly visible impacts of climate change and seasonal air quality issues, a significant problem in the populous Salt Lake City region, Walkingshaw said.
“[And] the state is probably very well saturated with solar” due to the legacy of Vivint Solar, a homegrown business later acquired by Sunrun, which maintained a large sales presence in the state, he added.
Proper VPP program design is crucial to drive wider home energy storage adoption, Richetta said. Otherwise, “the customer bears all of the cost of the battery, and it will therefore only be adopted in a limited manner, mostly for backup power and a basically daily cycle of solar self-consumption, failing to actually solve the problem” of an increasingly strained power grid, he said.
Richetta has praised Wattsmart as an exemplary VPP program. Rocky Mountain Power is the only vertically integrated U.S. utility to operate a VPP without a distributed energy resources management system acting as an intermediary, sonnen and ES Solar said. Wattsmart, which now has more than 40 MWh of distributed battery capacity, dispatches daily and is capable of providing eight different grid services, the companies said.
Other than Wattsmart, Richetta singled out San Diego Community Power’s Battery Savings Program VPP for its design, which encourages solar-only customers to “[add] a battery for the VPP attributes,” he said.
The SDCP program provides an upfront battery incentive of $350/kW and a $0.10/kWh performance incentive for 2-hour dispatch periods at up to daily frequency.
But these positive examples remain rare, Richetta said.
“Outside of Wattsmart, we have plenty of challenges getting the appropriate incentives in place to pay for the value stack of a grid-interactive [and] dynamically dispatchable battery, thus enabling the ‘Go Back’ market design,” he said.
Back in Utah, the sonnen-ES Solar partnership has retrofitted 200 to 500 homes per month to date, the companies said. For ES Solar, the partnership has boosted business during the winter months, which typically see fewer solar installations, they said.
And though the company’s new solar sales have a 95% battery attachment rate, the Go Back initiative “continues to drive the majority of ES Solar’s monthly battery sales,” ES Solar Vice President of Sales Zach Randall said in a statement.
sonnen also partners with Baker Home Energy to deploy home battery retrofits, Richetta said.
