The battery storage appliance

Apartment Building

Two articles we released last month referring to the future of energy storage as an appliance increasingly found in every home, similar to heat pumps and air conditioners today. But, are batteries really the next must-have gadget for your home? A new housing development in Utah may serve as a model for how to make this prediction a reality.

In response to a question about the evolution of energy storage products, a senior sales engineer at Panasonic, Daniel Glaser, stated that “eventually solar-plus-storage will be like air conditioning or HVAC.” Paul Daley, director of product and market strategy at OutBack Power, went even further, predicting that before the end of the decade, energy storage would become a mandated standard piece of equipment for new homes in some regions, like solar under California’s newly implemented building requirements. On the contrary, both industry experts note that battery storage is still expensive and will remain so over the next few years, even with expected price declines.

So, where does the reality of battery system costs align with industry expectations of a battery in every home?

Soleil Lofts in Herriman, Utah, could provide a blueprint for how these industry predictions come to pass. The new 600-unit development was designed with sustainability in mind, particularly to address increasingly poor air quality issues in the Greater Salt Lake City region. The housing complex is a net-zero development and all of Soleil’s apartments include high-efficiency appliances, including a battery storage system.

Every unit at Soleil Lofts includes a sonnen ecoLinx battery system. The ecoLinx can deliver 8 kW of power and store 20 kW-hours of energy, giving the apartment complex a combined capacity of 12.6 MW-hours of energy storage. Each battery is directly connected to a portion of the 5.3 MW of solar installed across 26 buildings and parking canopies, maximizing solar self-consumption and allowing the batteries to be recharged during a grid outage. Any solar energy that doesn’t get directly consumed flows to the battery systems for use later on. Each battery system can store enough energy to keep an apartment powered for days, even if the sun isn’t shining.

What makes this project work? At less than 9 cents per kW-hour, Utah residents pay some of the lowest electricity prices in the country, not correlating with incentives. Utah also has a state solar tax incentive but nothing for storage. Cheap batteries, such as sonnen batteries, use a higher-cost lithium-based chemistry with a longer lifetime and less safety concerns than many competitors.

Soleil was made possible due to a unique partnership between the property developer: Wasatch Group, the utility: Rocky Mountain Power and energy developers: Auric Energy and sonnen. Residents of Soleil enter into a standard lease for their apartment, but the solar and storage systems associated with each unit are owned by Wasatch Group. Rocky Mountain Power pays Wasatch Group for access to the batteries through a long-term contract for demand management. This agreement discharges the batteries when electricity demand is high or for other grid needs, as well as offsets the system cost. Residents get the benefit of clean, reliable power without the expense and risk of direct ownership.

sonnen’s experience in aggregating small batteries for grid-scale services, known as a virtual power plant, was critical in making the project a reality. While storage-based virtual power plants are still a relatively new concept in the U.S., sonnen has been acting as its own virtual aggregated utility in Germany for years, coordinating more than 10,000 residential battery systems in a peer-to-peer energy network. The battery systems, associated hardware and battery software performance are all guaranteed by sonnen for 25 years.

Rocky Mountain Power controls how the 5-MW virtual power plant will operate when called upon, primarily shifting solar consumption to meet daily evening peaks and discharging when electricity demand is high. Both actions benefit the entire region by reducing the need to fire up fossil-fuel power plants, lowering both greenhouse gas emissions and local emissions impacting air quality. If the batteries perform up to the level anticipated by Rocky Mountain Power, the utility plans to actively push for incorporating more distributed solar and storage resources across Utah.

Soleil Lofts is not the first virtual power plant to be deployed in the U.S., or the only case where residents get the resiliency benefits of storage without the upfront cost. However, solar and storage have never been deployed as a standard part of a new household and valuable tool for the grid at this scale . It could become the new norm for housing developments in regions with forward-thinking utilities or aggressive climate policies.

Unlike many big project announcements, Soleil is happening now. Resident began moving in September 2019 and the full development is scheduled to be completed by the end of 2020.

The potential impact of projects like Soleil, particularly in urban areas, is significant. Eventually, outfitting each of New York City Housing Authority’s nearly 200,000 public housing apartment units with a battery system may be possible. The result would be a flexible virtual power plant the size of a nuclear facility, in addition to clean and reliable backup power for the city’s most vulnerable residents.

In a future where battery storage is just another home appliance, today’s critical appliances – refrigerators, fans, heaters, outlets for charging devices – would be able to keep running even when disasters strike. If deployed at scale, there would be no more need for fossil-fueled power plants in urban neighborhoods. The technology and software to make this a reality exist today, it only takes a few innovators to make it happen.

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Seth Mullendore is vice president and project director for Clean Energy Group, overseeing projects ranging from customer-sited solar and battery storage to the replacement of power plants with clean technologies. Seth works with policy makers, project developers, industry, advocates, and community and environmental justice groups to advance clean energy policies and projects, with a focus on achieving greater access to solar and battery storage technologies for disadvantaged communities. Much of his work pertains to the research and reporting of energy storage technologies, policies, and supporting market structures. Prior to joining Clean Energy Group, Seth served as a Sustainable Energy Fellow with Union of Concerned Scientists and worked with Maine Clean Communities to help advance clean transportation initiatives. Seth holds a M.S. in Civil & Environmental Engineering from Stanford University, and a B.S. in Geosciences from the University of Southern Maine.

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