Green Design

Flexible Solar Cell Technology Lights Up Bus Shelter

altNew flexible solar cell technology, developed by engineering researchers at McMaster University of Hamilton, Ontario, has been installed in a campus bus shelter to provide power lighting for night-time transit users. The ability to bend the solar cells to fit the curved roof of the bus shelter is one of the main features of the technology.

“Our goal is to provide a clean, affordable power source for bus shelters that will let transit companies run Internet-based scheduling updates,” said Adrian Kitai, professor of Engineering Physics, who guided the project. The flexible solar cell project started as a master’s thesis for Wei Zhang, who subsequently worked as an engineer in the Department of Engineering Physics. The flexibility is achieved by tiling a large number of small silicon elements into an array, mounting them onto a flexible sheet, and connecting them through a proprietary method.

The two solar strips installed on the McMaster bus shelter are about 90 cm long and 12 cm wide. Each strip has 720 one-centimeter square solar cells and generates up to 4.5 Watts of power. A solar strip was mounted at each end of the bus shelter roof and connected to two energy-efficient, multi-LED, light fixtures. Each light fixture uses only 600 milliwatts of power and produces about the same light output as a three watt regular tungsten bulb, or what a small night light would use. The lights are bright enough for easy reading.

The solar cells capture sunlight during the day and convert it to electricity to recharge batteries located in each lighting unit. The batteries can hold enough charge to light the shelter for the better part of a night.

The solar cell research team is monitoring the installation to determine how much solar power is required to fully recharge the batteries based on weather conditions. Winter months will be a particular focus as shorter and overcast days, snow and cold can affect the charging ability of the solar cells and batteries.

(McMaster University)