The Sunny Prospects Of Photovoltaic Windows

Last year, Perth-based ClearVue completed the installation of an energy-generating glass atrium at the entrance of a shopping center. This so-called building-integrated photovoltaics is a new form of solar energy that is generated through glass that is completely clear. While photovoltaic (PV) windows have pushed the innovative front for a while, ClearVue’s method is different from the conventional use of silicon or thin-film to harness power. 

Instead it uses a spectrally selective polyvinyl butyral interlayer sandwiched between two panes of glass allowing most visible light to transmit but deflecting infrared light to solar cells in the frame, while UV light is converted to infrared and also deflected to cells on the window perimeter via total internal reflection. 

But not only does the project overcome the challenge of achieving absolute window clarity, ClearVue is also a breakthrough in efficiency. Traditional opaque solar panels capture energy in the form of light and transform it to power, but PV windows have to achieve a trade-off between generating light and electricity. ClearVue’s CEO Victor Rosenberg says the solar conversion efficiency of the window is 3.3% still lower than the 15% to 20% of most panels, but this can be compensated for by design as well as higher exposure especially for glassed-in-buildings such as urban offices. 

Here are some other perks and challenges: 

• PV windows take up less space than traditional rooftop and ground-mounted solar panels and can be installed in greenhouses or even your conservatory and skylights.
• Dense urban areas without access to rooftops could instead take advantage of large vertical window space. 
• PV windows reduce the thermal gain into a building and lower heat loss. 
• Large-scale commercialization could pose a challenge as the technology is building-integrated, meaning companies will have to convince the often conservative glass and construction sectors.