Trapping sunshine, letting it flow in dark homes

Resigned to a life of living in dark, damp houses where daylight does not even filter through, a few dwellers of the slums here and rural areas elsewhere in West Bengal and Tripura are waiting to usher in sunshine into their lives.

They will be part of a pilot project to try out a device that captures diffuse sunlight and bounces it back inside rooms, giving the effect of a 60-watt electric lamp. Called a “micro-solar dome”, this zero-fuel, zero-maintenance contraption will be installed on the roofs of 30 houses in the slums here, Bardhaman and the Sundarbans in West Bengal and places in Tripura. The lamp costs Rs. 300.

S.P. Gon Chaudhuri, renewable energy expert, led his team to launch this gadget through a Centrally funded low-cost research project. This is a “research-you-can-use” project awarded last October.

“The project carried a purse of about Rs. 4 lakh, and we wanted to develop an adaptive technology for capturing the daylight and streaming it back into homes in rural and slum homes,” he told

The Hindu after giving a demonstration of the simple contraption.

While normally a house has windows and even skylights to let in daylight, rural houses often have no more than tiny openings on the walls. In slums, the windows in the tenements are kept small, mainly for security reasons. Toilets, if any, will be dark. Most of these houses either have no electricity or have only a point. Once chores are done, the dwellers while away their time sitting and chatting outside to escape their depressing interiors. Children play in hazardous conditions outside their homes. The device could be a life-changer for them.

“It works on the principle of capturing sunlight using a micro-solar dome with a small diameter. This light is filtered through a PVC pipe with a highly reflective lining. Bright light emerges at the other end through a transparent glass shade,” Mr. Chaudhuri explained saying that while a roof-tile can be removed to install this gadget, it works equally well in a tin-roofed house.

A lever-based “switch” (the type used in a wall-mounted fan) allows the user to control light as it caps the roof-top dome with a lid that shuts off the light when not needed.

Besides lighting up the dark interiors in daytime, these lights can help improve productivity, he said.

“These ill-lit homes affect productivity. Women cook near outside. But they can do little in the summer when it is too hot to go outside. With these lights, children can also study indoors,” he said.