KCCI-TV: More than 9,500 solar panels are generating clean energy at Alliant Energy’s new Marshalltown Solar Garden. The company said the pilot project combines solar power and a battery to generate, store and deliver electricity to customers. The company said the 2.55-megawatt AC solar system in Marshalltown can power nearly 400 homes. With full sun, the solar panels can also fully charge the battery within two hours. When discharged, the battery can power nearly 200 homes for two hours, Alliant Energy said.