Lennar has developed The Arches community within the Redpoint village of Summerlin this year. The homebuilder is selling 51 homes with integrated rooftop solar power systems that include 20 solar panels to provide 7.8 kilowatts of electric power when the sun is shining, a back-up battery storage system that provides 13.5 kilowatt-hours of electricity when the sun isn’t shining, as well as two charging stations for electric cars. (Lennar)