Chicago may be known as the Windy City, but don't sell short its sunlight. According to veteran Chicago weather observer and recipient of the National Weather Service's Thomas Jefferson Award, Frank Wachowski, the city sees at least some sun on about 320 days a year. A new solar power project involving one of the city's most iconic buildings is about to take advantage of that.
The Willis Tower (formerly the Sears Tower) is on deck to become an enormous vertical solar farm with the installation of photovoltaic glass panels on the south side of the skyscraper's 56th floor.
Two esisting windows on North America's tallest building were replaced last November with new high power density photovoltaic glass units (PVGU) developed by Pythagoras Solar. These innovative windows sandwich a common solar cell between two panes of glass. A reflective prism inside the PVGU directs angled sunlight onto the solar cells, but still allows daylight to shine through.
Each window is about one square meter and capable of generating 120W of power.
Energy harnessed by the transparent solar windows are expected to reduce heat gain, and therefore cooling costs as well.
"We are excited to launch this pilot with Pythagoras Solar's leading-edge solar window solutions as a test for not only the energy savings that can be achieved, but the potential they represent to actually generate power through the sun," said John Huston, in a PRNewswire press release. He's Executive Vice President of American Landmark Properties, one of the ownership partners of Willis Tower.
Currently, the photovoltaic cell in each PVGU is capable of generating the same amount of energy as a standard roof-top mounted solar cell. However, if successful, the high-profile pilot project could expand to the building's east and west facades and potentially generate 2 Megawatts of solar power.
Image: Murat Taner/Corbis