In this new solar-powered apartment complex, all 600 units have batteries that form a virtual power plant

With a battery in every apartment, the whole complex can store extra power when the sun shines, and then move it around where it’s needed at night.


If you walk inside this new one-bedroom apartment outside Salt Lake City, you might not recognize the large object around the corner from the fridge. Roughly the size of a refrigerator itself, it’s a battery. The apartment complex, which will include 22 buildings and 600 units when complete, is the first to put batteries inside every apartment, connected to solar power on the roof—so the local utility can use it as a virtual power plant.


“This is the kind of community that’s truly a community of the future, where solar and solar batteries are literally built into your life,” says Blake Richetta, chairman and CEO of Sonnen, Inc., the company that makes the batteries used in the project, called Soleil Lofts, built by the developer Wasatch Group. Sonnen has previously installed batteries to store solar power in groups of single-family homes in the U.S., but this will be the first time that those batteries will be controlled by a utility. That means that the utility can manage the system to avoid using a fossil fuel-powered “peaker plant” when energy demand is highest.

[Image: courtesy The Wasatch Group]

“When there’s excess solar-generated energy produced, instead of just pushing it into the grid right away, it’s going to be shifted and harnessed in the batteries,” Richetta says. “Rocky Mountain Power will look at that in real time, and every day will constantly be able to say, okay, when can we use this solar?” Right now, in areas with a lot of solar power, there’s often so much energy produced when the sun is out that it can’t be used; without battery storage, when power is needed at night, utilities have to turn to more polluting sources.

The developer, the Wasatch Group, saw investing in solar power and batteries as the right thing to do for the region, which is already experiencing climate impacts including worsening wildfires and droughts. “We looked at how are we going to be responsible stewards,” says Jarom Johnson, chief operating officer for Wasatch Premier Communities. “This was probably the best option that we could identify that allowed us to say, ‘Hey, we’re going to push the envelope.’ It’s going to challenge our standard mantra for development. But we have specific outcomes we’re trying to pursue, which are we want to limit our footprint, and we want to allow a large portion of individuals to be housed without throwing a bunch of carbon in the air.” The company took advantage of federal and state tax credits to offset the cost of the project, and will be paid by the utility for access to the virtual power plant.

The apartments are all-electric, so everything can run on the system; the complex will also have more than 100 chargers for electric cars. In a disaster, if the rest of the grid goes down, the batteries, with 12.6 megawatt-hours of storage, can provide power for a few days even if the sun isn’t shining. The buildings are also designed to maximize energy efficiency, so tenants can save money on utility bills. Tenants will begin moving into the first apartment building in September, and the rest of the development will be completed by the end of 2020.

The battery, visible to the left. [Image: courtesy The Wasatch Group]
The developers made a deliberate choice to put each of the 600 batteries inside apartments rather than in an unseen utility room. As a practical matter, it’s more efficient to send electrons from apartment to apartment. But the choice was mostly a statement to residents. “We wanted to be able to demonstrate [the impact of the project] in a way that people can say, ‘Hey, I’m proud to take the pledge to live differently for the betterment of the overall society,'” says Johnson.

About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."