Flexible solar strips shed light on bus waiting times
By Karen Sprey
June 15, 2009
Canadian research engineers at McMaster University in Ontario have developed flexible solar cell technology which generates enough power to light bus shelters as well as send internet-based updates of transport schedules. The attraction of the solar strips is that they can be bent to fit the curved roof of the campus’ bus shelters.
Each flexible solar strip – measuring 90cmx12cm – contains 720 one-centimeter square solar cells generating up to 4.5 watts of power. A solar strip has been attached to each end of a bus shelter and connected to a multi-LED, battery-operated light fixture. These energy-efficient lighting units use only 600 milliwatts of power and generate the same light as a three-watt tungsten bulb, or small nightlight, making them bright enough for reading and general safety for night-time transit users.
The solar cells capture sunlight during the day and convert it to electricity, which recharges the batteries in the lighting units. The batteries hold enough charge to light the shelter for most of the night.
The researchers are monitoring the technology to determine how much solar power is required to fully recharge the batteries in different weather conditions, including winter, when overcast days, snow and cold can affect the charging ability of the solar cells and batteries.
The flexibility has been 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 researchers hope their prototype will help commercialize the technology.
If you happen to be part of McMaster University and use the transit system, the research team is keen to hear about your experiences and any feedback about the solar-lit bus shelters. The team can be contacted via email.
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