Chicago’s landmark Willis Tower, earlier known as the Sears Tower, is preparing to transform into a solar power plant. The project will add pilot solar electric glass on the south side of the 56th floor. The photovoltaic glass developed by Pythagoras Solar will replace the existing window panes; produce the same energy as a conventional solar panel and reduce the heat gain.
The project could expand to generate 2 MW, which is equal to a 10 acre solar field of panels.
The project is a joint venture between owners of the tower and the manufacturer to show the feasibility of the building integrated photovoltaic (BIPV) system, which reduces heat gains and cuts cooling costs.
The new windows, termed high power density photovoltaic glass units (PVGU), are a hybrid technology that embeds typical monocrystalline silicon solar cell horizontally between two layers of glass to form a single tile. An internal plastic reflective prism directs angled sunlight onto the solar cells but allows diffused daylight and horizontal light through.
The manufacturer, Pythagoras Solar claims that the vertically integrated solar cells will produce the same amount of energy as normal rooftop-installed solar panels.
This technology means that cities that have less land than skyscrapers can produce more efficient and clean energy. It is also an innovation in that the solar heat gain reduces the direct temperature and cuts down on cooling needs.