The tallest skyscraper in America, Chicago’s Willis Tower, will soon be generating its own solar power. The tower (which used to be known as the Sears Tower) is going to be fitted with high power density photovoltaic glass units (PVGUs), which will replace the existing windows on the south side of the 56th floor. The solar panels windows will be made by Pythagoras Solar – they’ll preserve daylighting and the view while generating power and reducing heat gain. The panels will produce the same amount of energy as a conventional solar panel.
The new panels / windows are a hybrid that lays monocrystalline silicon solar cells horizontally between two layers of glass. An internal plastic reflective prism directs angled sunlight onto the cells while allowing diffuse daylight and horizontal light through, which lets natural daylight inside. Pythagoras Solar says that their solar windows will generate the same amount of electricity as traditional rooftop solar cells while at the same time lessening the amount of heat reaching the inside of the building. This will lead to further efficiencies as air conditioning needs potentially will drop.
Depending on the results from this first phase, the project could eventually expand and has the potential to turn the Willis Tower into a 2 MW solar farm.