Photovoltaic (PV) panels have the potential to be easily and inexpensively incorporated into any house or building. As Kiss explains, “they’re an energy-generating technology that is a building material, too.” Costing about $15 per square foot (about the same as standard cladding), thin film panels end up being a two-for-one deal: Buy attractive cladding, get sustainability for free. In order to get the most bang for the energy buck, there are three types of solar collectors in each IJsselstein house: passive, electrical, and thermal. Passive collectors soak up the sun on the south and north sides of the façades, lazily generating heat by doing relatively little. Also on the façades of the solariums, electric solar panels actively convert light into wattage, fueling appliances and lamps within the homes. On the solariums and the rooftops sit solar thermal panels, which heat water for showering and dishes and fuel the radiant heating system that runs underneath the ground floor of each house. Since the houses are well insulated, heat has little chance to seep out through the walls. It all proves, van Zwieten says, “that you can combine nice housing and comfort with energy savings.”  Photo 2 of 3 in Run by the Sun