Nation’s Largest Residential Battery Demand Response System Being Built in Utah

Sept. 18, 2019
A new 600-unit apartment complex and sustainable community in Utah’s Salt Lake Valley will feature a residential virtual power plant (VPP) that its backers say will be the largest residential battery demand response system in the US.

A new 600-unit apartment complex and sustainable community in Utah’s Salt Lake Valley will feature a virtual power plant (VPP) that its backers say will be the largest residential battery demand response system in the US.

Local utility Rocky Mountain Power will manage the virtual power plant to shave peak demand and provide behind-the-meter demand response services and emergency back-up power.

“As the developer of Soleil Lofts, we started with the firm belief we could build a community that was solving the Salt Lake Valley’s serious air quality issues today and in the future. That belief led us to partner with Rocky Mountain Power, sonnen and Auric Energy for the development of an all-electric community utilizing solar and batteries.” said Wasatch Group CEO Dell Loy Hansen.

Soleil Lofts’ apartments are all-electric with an energy system that includes on-site solar PV, battery energy storage system (BESS) and electric vehicle chargers. The systems will switch into island mode and operate autonomously to provide electricity when grid outages occur. In addition, more then 150 EV chargers linked with a Rocky Mountain Power demand response system will helps reduce emissions from transportation. Wasatch is offering tenants one year of free EV charging as an incentive.

All electric apartment complex

“The Soleil Lofts project is the first all-electric residential apartment complex that uses solar and a storage system in each unit managed by the local utility,” said Jay Oman, Wasatch Group vice president. “Without real-time demand response functionality managed by the local utility, there would not be much value in the VPP. The sonnen battery is connected to the entire apartment through the electric panel, so it has the ability to run all the devices in the apartment.”

The development cost for Soleil Lofts solar and storage totaled more than $30 million, but the combination of federal and state tax credits, depreciation and funding from Rocky Mountain Power made the project financially viable. “Overall the project is profitable, but we are not disclosing any detailed financial information at this time,” Oman said in an interview with Microgrid Knoweldge.

Electricity generation and distribution for Soleil Lofts centers on 5.2 MW of solar, more than 600 sonnen batteries offering a collective 5 MW/12.6 MWh, and more than 150 EV chargers. Energy consumption will be dawn from on-site sources first, which will be able to meet most of tenants’ electricity needs, according to the project partners.

Design of virtual power plant

Auric Energy designed Soleil Lofts’ solar power and BESS. Rooftop solar arrays comprised of 430-W Solaria PV panels are, or will be, installed on each of the 21 apartments buildings and clubhouse. Twenty-kilowatt sonnen ecoLinx batteries are installed in each apartments living room.

Project developers considered building a single battery-bank system for Soleil Lofts but couldn’t find one that met Rocky Mountain Power’s need for a safe, long-term utility asset, Rocky Mountain Power Managing Director Bill Comeau told Microgrid Knowledge. A direct connection between the utility’s automated energy management system and sonnen’s VPP software will enable Rocky Mountain Power to manage the VPP so as to optimize its value to Soleil Lofts and the utility grid.

The project is scheduled to be complete in December 2020, but residents are beginning to move into apartments this month. At $1,200 per month, rental costs at Soleil Lofts are in line with similarly sized apartments in the Herriman, Utah area. Tenants will be responsible for their energy bills.

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About the Author

Andrew Burger

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