sonnen, a smart energy storage and virtual power plant technology company, and ES Solar, one of the largest solar installers in Utah, have announced initial results following the launch of their “Go Back” program with utility Rocky Mountain Power (RMP).
The “Go Back” program, which the companies say is a first-of-its-kind virtual power plant (VPP) business model, targets existing residential solar customers that don’t have smart grid interactive batteries, a segment of the market often ignored by solar installers.
“ES Solar has established a new, replicable business model and sales marketing strategy designed to inspire the revolution away from solar alone and into grid-interactive and responsive solar that supports, rather than becomes a nuisance to, society’s energy grid,” said Blake Richetta, chairman and CEO of sonnen USA.
Transforming intermittent resources into dispatchable assets
VPPs use advanced software and communication technologies to manage, optimize and coordinate the output of various types of distributed energy resources (DERs), including residential solar and storage systems. VPPs aggregate tens, hundreds or even thousands of DERs into a single dispatchable resource that can be used to bolster the grid during times of peak demand.
Each DER that’s connected to a VPP must be dispatchable, or able to quickly adjust the amount of electricity it sends to the grid. Solar is an intermittent power source so it is not dispatchable unless it is paired with an energy storage system, typically a battery.
And therein lies the opportunity for the “Go Back” program.
There are nearly 80,000 homes with solar systems in RMP’s Utah service territory that don’t have connected smart grid interactive batteries.
By upgrading these battery-less solar systems, RMP can convert a large rooftop solar fleet from intermittent generation to a firm dispatchable grid asset – lowering emissions and improving the reliability of the grid.
So far this year, ES Solar has installed between 200 and 500 sonnen batteries each month, totaling 18 MWh of storage.
“Existing solar customers are very interested in adding an intelligent energy storage system to their solar array, not just for backup power, but for the other benefits that a storage system can provide,” said Zach Randall, VP of sales at ES Solar.
ES Solar has plans to retrofit 32,000 homes with sonnen VPP batteries over the next five years, firming 40% of all residential solar arrays in Utah.
In addition to proactive backup power and lower emissions, participants in the “Go Back” program may receive an upfront incentive of $600/kW on their battery system and annual bill credit for grid services.
Utilities and VPPs
RMP has been actively pursuing VPPs since it launched its Wattsmart Battery program in 2021. Through Wattsmart, RMP manages participant’s batteries as part of the utility’s smart power grid. The program also offers rebates and incentives ranging from $400 to $6,000, depending on the battery output.
RMP has directly integrated its behind-the-meter battery VPP into its grid operating system, without a distributed energy resources management system (DERMS) solution in the middle.
Other utilities and grid operators are also exploring how to best leverage VPPs. Puget Sound Energy, Washington state’s largest utility, recently expanded its VPP partnership with cleantech software company AutoGrid and San Diego Gas & Electric is running a VPP pilot project to help the grid meet electricity demand when summer temperatures rise.
The Public Utility Commission of Texas announced two VPP pilot programs that will become dispatchable power resources for the Electric Reliability Council of Texas, and CPower Energy, a Baltimore-based energy management firm, is creating VPPs for the New York Independent System Operator.
A scalable business model
The “Go Back” business model is not only good for customers and RMP, but also for solar installers. ES Solar said the initiative has been a game changer, with approximately 75% of its year-to-date sales stemming from the program.
It’s “an excellent method to smooth out a solar contractor’s business over the course of the year, by providing a terrific opportunity for high-volume during the winter months,” said Randall, who noted that installing a battery in a garage is more feasible in the winter compared to selling and installing rooftop solar.
