If consumers are willing to purchase and install solar energy on their homes and they are also willing to purchase and install batteries so they can continue using that solar energy at night when the sun goes down, could those same batteries be used by the electric utility as a grid asset? In Utah and Idaho, the answer to that question is yes. And utility Rocky Mountain Power (RMP), which serves 1.2 million customers in Utah, Idaho, and Wyoming, has figured out how to tap into those batteries and use them when it needs them.
Wattsmart battery programThe RMP Wattsmart Battery program was launched in December 2020. The program pays customers with existing solar PV who want a battery an upfront rebate equal to $600 per kW of battery storage capacity that is available for discharge. In addition, customers receive ongoing bill credits of $15 per kW per month for participating in the program and there is a mandatory minimum four-year commitment. The agreement is transferable if the customer sells their home. In exchange for the rebate and the bill credits, RMP can tap into the battery and use it when it needs it.
Qualified installers and equipment must be used and RMP verifies that it can communicate with the battery via the homeowner’s WIFI before enrollment in the program is complete.
Subscribe today to the all-new Factor This! podcast from Renewable Energy World. This podcast is designed specifically for the solar industry and is available wherever you get your podcasts.
Listen to the bonus episode from the RENEWABLE +Series on green hydrogen’s future, featuring developers, investors, and researchers.
ES Solar and sonnen
Two of the program partners, smart battery manufacturer sonnen and solar installer ES solar, said on August 24 that the program is expanding, and they expect to put another 35 MWh of grid-interactive battery capacity online in 2022 via the Wattsmart program. This equates to about 1500 new ES Solar customers. The company added that it expects to add more than 5,000 customers in 2023.
With over 2,000 customers already enrolled in RMP’s Wattsmart program, ES Solar said that its model for selling grid-interactive solar plus utility controlled residential batteries is a blueprint for an authentic energy transition, abandoning traditional solar grid defection and reliance on net metering. The company said it is selling over 6 MWh of energy storage every month in Utah and Idaho as RMP has gradually ended its solar net metering subsidy to shift focus toward replacing solar alone with solar + energy storage with the Wattsmart Battery Program.
The Idaho Public Utilities Commission approved the Wattsmart program in April 2022, making Idaho the second state to embrace Wattsmart, after Utah.
ES Solar said it targets existing solar owners, both within its customer base and externally, to retrofit homes with Wattsmart-enrolled batteries. With the addition of a sonnenCore+ energy storage system, individual home PV systems are transformed from sources of intermittent and erratic generation to firm dispatchable grid assets that provide value to grid operations, said the company. The resulting solar battery networks help decarbonize the environment and could be seen as a blueprint for replacing certain peaking power plants.
The battery swarmIn the existing Wattsmart fleet, RMP has direct control over the aggregated batteries and can dispatch the battery “swarm” on demand to meet grid conditions with daily, dynamic solar time shifting and directed load curtailment, plus frequency response and directed solar grid injection when the grid needs power, as opposed to when it is sunny.
The 2000 customers enrolled in the Wattsmart program plus the residents of the 600-unit Soleil Lofts, which acts as a virtual power plant, mean that RMP “is directly controlling more residential batteries dynamically and on a daily basis, than any utility controlled battery consumer program in the nation,” sonnen said in a press release.
Unique solar + utility partnershipThis model for selling grid-interactive solar plus utility controlled residential batteries and the strategic partnership with RMP is a departure from traditional contractor ideologies that position batteries solely as tools for back-up power or off-grid living and the utility as an adversary, the companies said. The ES Solar approach and the Wattsmart Program prove that true energy transition requires collaboration from the grid, the utility, government, and the citizens of a community.
“As Rocky Mountain Power’s battery program grows, ES Solar is succeeding in overcoming the complex concepts and challenges associated with effectively integrating residential solar + storage into the broader energy system. As this radical model expands into thousands of new homes, so does the use of batteries for the betterment of individuals, society and the environment, which is the ultimate purpose of a solar battery,” said Blake Richetta Chairman and CEO at sonnen, Inc.
Learn about the virtual power plant at Soleil Lofts and its partnership with RMP in the video below.
