Making Solar Possible, Even When the Sun’s Not Out

By Katherine Jennrich
October 20, 2015
Solar power panels are spread across a store rooftop

At Walmart, the quest to be supplied 100% by renewable energy is real. One way we’re working toward this is our procurement of solar energy. We’re already the No. 1 commercial solar energy user in the U.S. and on track to double our number of on-site solar energy projects at Walmart stores, Sam’s Clubs and distribution centers in the U.S. by 2020 (compared with our 2013 baseline). We’re talking more than 480 sites.

But the rush of my job, and the rush for those around me, comes from the fact that we work for a company that refuses to stand still. Generating solar power alone is not enough. We not only need to produce solar, but capture it for use during the periods of highest demand on the traditional energy grid.

So, for more than a year, we’ve piloted a pair of 9-kilowatt batteries and 11 30-kilowatt batteries at 13 of our stores across California. These batteries, developed in collaboration with Solar City – one of the largest solar developers in the U.S. – have been tied into our on-site solar installations to successfully capture and use clean solar power, managing our peak energy demand, both in our stores and subsequently in the communities we serve.

We’re no longer limited to only using solar when the sun is shining. And that’s lowering our energy consumption and bills, which ultimately saves our customers money and contributes to a more sustainable future for the planet we all call home.

Five years ago, if you were talking about battery storage in renewable energy circles, you were probably in a dark distant corner of an expo hall at a solar conference. Now, those conversations are multiplying in prominent spaces around the world. There are entire conferences dedicated to it. In fact, last week, Walmart received a 2015 Energy Storage North America Innovation Award for our leadership in distributed energy storage.

But this recognition wasn’t earned simply because of our demonstrated ability to store and distribute energy during high-demand periods. Our success in this area opened the door to yet another game-changing opportunity. We’ve already proven technology can be built to learn and predict spikes in our own energy curve. What if we could also build in a way for our stored solar power to be distributed during the event of a power outage – as a generator?

Walmart isn't just wondering about this question. We’re acting on it.

We’ve worked with SolarCity to contract five 200-kilowatt DemandLogic systems, which will be installed at select stores in California by the end of January. Four have been designed to provide backup power for sales floor lighting in the event of a power outage, in addition to kicking in to reduce peak demand during the highest energy consumption times of day. Another, to be installed at our Huntington Beach store, will also have the ability to back up refrigerated cases.

This has the potential to take something that’s already a very big deal and make it even bigger. Walmart is committed to serving our communities, even in times of crisis – so the faster we can get power restored to our buildings after an outage, the faster we can get back to serving our customers. We look forward to the day we’re ready to begin deploying this kind of technology across the greater footprint of Walmart stores, Sam’s Clubs and distribution centers.

But it's not just about what’s in it for us. This is about contributing to something that has the potential to benefit the entire retail industry and the world. It’s about being a good steward for the environment and the communities we serve.