Walmart has installed solar roofs on over 150 of its stores. It's Kirstin and Mack's job to install more. By 2020, Walmart will have installed solar roofs on 1,000 stores across the country. Kirstin and Mack will be making a difference, one roof at a time. Visit <a href="http://www.walmart.com/livebetter">http://www.walmart.com/livebetter</a> to learn more.