We embed thermoelectric nanomaterials into window glass to generate thermoelectricity from the temperature gradient between the solar-heated outdoors and the relatively cold indoor temperature. Until now thermoelectric generators have been built on a single side of a substrate, therefore requiring the two temperature environments to exist on the same side of the substrate. For this application, substantially thick window glass (>5 mm) serves as the interface for which the hot side is on the exterior side of the window and the cold side on the interior side. We demonstrate thermopiles made of nanomaterials integrated through the glass. With meticulous engineering, 300 W of power can be generated from a 9 m(2) window for a temperature gradient of 20 degrees C, which is typical in hot climates, such as the desert areas in the Middle East and African Sahara. A thermoelectric window can be a supplementary power source for waste heat recovery in green building technology.