Ground mounted solar farms tend to occupy a lot of space; area that often isn’t available in urban areas. Cities and the suburbs offer a sea of rooftops for solar power harvesting – but then there’s the sides of buildings that can be utilised as medium scale solar farms as well.
Chicago’s Willis Tower (formerly Sears Tower) is a 110-story office building, towering 440 metres above the ground. A pilot project commenced in November last year using building integrated photovoltaics (BIPV) on the south facing windows of the Tower’s 56th floor.
According to Pythagoras Solar, the company who designed, supplied and installed the see-through solar panels, the project has the potential to expand to a surface area allowing over two megawatts of solar electric generation.
In addition to generating power, the solar windows are an excellent thermal barrier, reducing heating and cooling costs and associated emissions.
Pythagoras Solar claims its PVGU product delivers four times the power density of comparable BIPV technologies and provides better daylighting compared to other BIPV products. PVGU has a power output of 140 watts per metre squared, a U-value of .24, solar heat gain coefficient of .15 and 50% visible light transmission.
Pythagoras says world net electricity generation is expected to increase by 77 percent between 2006 and 2030, from 18.0 trillion kilowatt hours to 31.8 trillion kilowatt hours. Buildings are the largest consumers of energy globally, but among the least efficient. Using solar power products as part of the design of a building rather than an afterthought can go a long way to meeting environmental regulations, reducing energy consumption, and boosting real estate value.
