Ingenious PV Glass Window Hits Chicago

Pythagoras Solar makes a revolutionary solar-powered window – literally an insulated window with integrated photovoltaics – that has the ability to turn buildings into massive power producers. The company has been testing a pilot project on the south-facing windows of the 56th floor of Willis Tower, formerly known as Sears Tower. If the pilot goes well, Willis Tower could end up with a surface area of up to two megawatts of solar.

Pythagoras Solar claims to be the first company to offer a fully-integrated photovoltaic glass unit, or PVGU, that balances energy efficiency, high power density, and transparent design in a meaningful way.

In other words, the PVGU replaces insulated glass units and has a low U-value. At the same time, the solar-integrated window delivers the highest power density of any other building-integrated photovoltaic solution by generating up to four times more of electricity, according to the company. The PVGU also allows natural light and a certain level of transparency (see picture).

The first PVGU offerings have been designed specifically for vertical curtain wall and skylight applications. Future products may include roof tiles and spandrels, according to Pythagoras.

Pythagoras told Jetson Green in an email the PVGU is priced to deliver a 5-year return on investment – a calculation that includes energy efficiency and power generation gains. Specifically, the PVGU is about $125 per square foot in U.S.-based projects.