SALT LAKE CITY — The first residents of an all-electric and energy efficient community — the largest residential battery demand response project in the United States — are settling into new apartments. Their cars are tucked neatly beneath solar panel covers and their electric cars can plug into charging ports. Inside each apartment in the Soleil Lofts development, a Sonnen battery is humming silently close to their living room.

The residents sign on knowing their backup power can be controlled by the utility and dispatched to the grid as needed by the local utility, Rocky Mountain Power.

The full complex will be finished in the next two years, but the virtual power plant established when the first building opened is a blueprint for developments outside of Utah, according to the real estate developer Wasatch Group.

The Soleil Lofts apartments, under construction in Herriman, Utah, seeks to attract environmentally conscious customers who want to hasten the transition to all-electric and clean energy living. The project represents a collaboration among Rocky Mountain Power, battery developer Sonnen, solar developer Auric Energy and Wasatch. All the partners have plans for modeling the success of the Soleil projects.

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"[T]he long term thing for us is how do we provide battery solutions for our customers?"

Bill Comeau

Managing director of customer innovations, Rocky Mountain Power

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The effort is an opportunity for the Pacificorp subsidiary to work with a partner that has experience with energy storage, as the utility learns to better integrate batteries into the grid and enable growth from renewables, according to Bill Comeau, Rocky Mountain Power's managing director of customer innovations.

When complete, the planned community's 22 buildings will have 600 apartment units with 12.6 MWh of battery storage, 5.2 MW of solar panels, 150 stalls of EV chargers and an overriding focus on energy efficiency. Utility access to the 600 Sonnen batteries will turn the complex into a grid resource.

"In the big scheme of things, it's actually really small," Comeau told Utility Dive. "But the long term thing for us is how do we provide battery solutions for our customers?"

Capitalizing on customer demand

The Soleil Lofts development is one of several grid modernization efforts regulators have approved from Rocky Mountain Power in Utah. The utility is partially funding the energy storage systems although they will be behind-the-meter resources owned by Wasatch.

"As a utility, we're 100% controlling the batteries for the greater good of the grid," Comeau said. "And then we're just trying to figure out how we can scale that to provide more options for customers."

The utility joined the collaboration following growing consumer demand for distributed energy resources. According to Comeau, customers have been asking for rooftop solar for the past five years, but they have more recently started asking for energy storage as well.

Customers often ask the utility directly for distributed solar power, he said, making the utility a natural partner in this project. However, distributed energy developers and installers continue to promote a variety of partnerships, including without direct involvement from the utility.

​"In Utah, the value proposition is very strong here" to partner solar with other developers, like roofing and HVAC professionals, Complete Solar's Dave Anderson said.

"When utilities are offering solar, I think that's great," Anderson said. "Maybe the only issue with utilities offering solar products is that again, you're limiting the market innovation that can happen, in terms of figuring out the best, least expensive most efficient way to get power to any given consumer."

Like other projects where distributed resources are operated by utilities, individual systems reserve a set amount of power to ensure the complex can be powered in case of a grid event. For example, Hawaiian Electric will have access to aggregated power from Sunrun's solar-plus-storage systems across Oahu, but will only call on individual systems for 30 minutes at a time.

"There may be instances where the utility will require half of" the available battery reserves, Nic Evans, Auric Energy, told reporters in a completed Soleil Lofts apartment. Evans helped design the system used in the project.

Rocky Mountain Power is looking for "storage assets within 50 to 100 MW blocks, so they can show that they have a certain amount of storage available," he said.

The 600 batteries "can all work together as a hive to push the power that the grid needs at any given moment," Evans said.

The Sonnen ecoLinx batteries were chosen for their duration and longer lifespan.

Auric worked closely with Rocky Mountain Power to understand how to best equip the apartment complexes in order to support them during a catastrophe or outage situation using the same transformers as the rest of the grid, "so the power could ebb and flow seamlessly between the storage, the solar and the utility," Evans said.

The project reflects consumer interest in a clean energy community, with high-efficiency appliances and full-electrification, according to Jay Oman, vice president of Wasatch Group's solar division. One aspect of that is the built-in buffer to add more electric vehicle (EV) chargers.

"What we did is we actually put more infrastructure than we needed for EV chargers, so we could add EV chargers if there's more demand," Oman told Utility Dive. 

Penciling out this project

About 50% of the cost of the solar and storage components of Soleil is earned back in federal, state and utility subsidies, according to Wasatch.

"It's a huge part of it. We wouldn't be able to do [Soleil Lofts] without" the tax credits, Oman told reporters.

The tax credits are beginning to phase out. On a federal level, the solar investment tax credit will zero out in 2022 for residential developments and it will pare down from 30% to 10% for utility, commercial and industrial projects.

"It's just part of the process of the evolution of new technologies," Comeau said.

Soleil was showcased in the middle of the Solar Power International and Energy Storage International conference in Salt Lake City, as the Solar Energy Industries Association launched a campaign to "Defend the ITC."

Price competitiveness was key to the project, according to multiple stakeholders, to prove that it could be replicated even in conditions of low energy prices, such as the ones in Utah.

"We wanted this to be a complete solution that other people can take, and then copy and hopefully do better," Oman said.

The successful collaboration among the utility and the various other stakeholders has already encouraged the development of more virtual power plants for Wasatch.

Wasatch is looking at Soleil as a starting point for similar opportunities to develop efficient housing and earn revenue by acting as a grid resource. The group develops a variety of commercial and office buildings, as well as residential structures, and is evaluating other potential partnerships.

"We have another partner that's looking at just basically working in CAISO," to bid capacity from a virtual power plant into the market, Oman said.

"It's an easier barrier to entry to get past," as opposed to developing an agreement with an investor-owned utility.