In Marshalltown, Alliant Energy is testing a solar energy battery-storage solution different from the one in Decorah

Alliant Energy is in the process of building a battery storage system in The Vennehjem subdivision that will be used as an "electron bank" to manage capacity on a circuit.

Meanwhile, the utility has just completed another solar energy storage project—this one, in Marshalltown, where more than 9,500 solar panels now generate clean energy at the Marshalltown Solar Garden. This pilot project combines solar power and a battery to generate, store and deliver electricity to customers.  

"This solar-battery combination allows us to provide our customers with solar power during the day and night," says Alliant Energy Iowa President Terry Kouba. "The solar field adds power to the grid when the sun is shining and then our battery allows our customers to continue using this renewable energy resource in the evening when the sun isn't shining."

The 2.55-MW AC solar system in Marshalltown can power nearly 400 homes. With full sun, the solar panels can also fully charge the 548kWh battery within two hours. When discharged, the battery can power nearly 200 homes for two hours. The solar garden became operational in mid-February and the battery was just put into service this week.

The Marshalltown project becomes Alliant's third battery sites in Iowa.  In addition to the projects in Decorah and Marshalltown, a battery in Wellman provides resiliency and reliability in a rural area with an abundance of customer-owned solar systems.