IIT-B students light up slums at low cost

In the dimly lit shanties of Govandi’s Rafi Nagar, light pours in from bottles of water that are hung from the tin roofs. Operating as receptacles of sunlight, the 1.5-litre plastic bottle captures solar energy and disperses it into the tiny room, generating light equivalent to a 50-55 Watt bulb.

In the dimly lit shanties of Govandi’s Rafi Nagar, light pours in from bottles of water that are hung from the tin roofs. Operating as receptacles of sunlight, the 1.5-litre plastic bottle captures solar energy and disperses it into the tiny room, generating light equivalent to a 50-55 Watt bulb.

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This energy innovation, piloted by a group of 16 Indian Institute of Technology-Bombay (IIT-B) students from the material sciences department, has already been set up in some of the Govandi slums and in temporary hutments on the institute’s Powai campus.

The bottle, filled with water, is fitted into a metal plate, which is then inserted into the tin roof. The bottle is sealed, ruling out evaporation, and bleach is added to the water to keep it pure. The cost of putting together one such unit is around Rs 100, and it can last for up to two years.

“In the slums, they have to keep their lights on through the day and the night, as it is completely dark. With these bottles, it helps cut down a lot on the electricity consumption,” said Jaydeep Soni, 21, a student involved in the ‘Liter of Light’ campaign.

The project, however, has some drawbacks, too. The bottles can be fitted into tin roofs, but not in a concrete roof. If there is foliage above the roof, exposure to sunlight becomes a problem. Also, the group is yet to figure out how the units would work during monsoon.