From Brownfield to Greenfield – Visualizing the Worlds Largest Urban Solar Power Plant. Today, Exelon and SunPower announced plans to develop a 10 megawatt solar power plant in the south side of Chicago- the largest of its kind in an urban setting. Considering this monumental announcement, on Earth Day nonetheless, we decided to create a real-virtual view of the array using Google Earth, SketchUp and some other tools at our disposal.