Concentrated photo-voltaic solar facade...
more info: http://www.mohsen-saleh.com/2011/10/light-farm.html
Lightfarm is a system that utilizes building facade and rooftop for collecting and concentrating light rays which then is used for heating and power generation by HCPV photovoltaic cells. This kind of PV has an efficiency of 40% and is suitable for concentrated light up to 500 to 1000 times the intensity of sun rays.
In this case, instead of using conventional photovoltaic of 12 to 19% efficiency, we would concentrate light by building façade using the thin plastic Fresnel lenses accompanied by a glass layer, and then utilize a few Sq. centimeters of HCPV to generate electricity for the household.
Photovoltaic cells would provide electricity with an efficiency of 40%, and the 60% formerly waste of energy is transmitted to heat-sinks for water and space heating purposes.