The Centre may spend Rs 1,000 crore in subsidies to offer a new solar lighting solution to one crore families living in shanties and slums where rooms are poorly lit all through the day. The ministry of new and renewable energy has already committed Rs 500 crore for the two-year project while another Rs 500 crore is under consideration, said S P Gon Chaudhuri, chairman of Kolkata-based Renewable Energy College that invented the sunlightcapturing gadget. Installed on the rooftop, the gadget sends sunlight into rooms where even windows don’t let in sunlight during the day, using a special dome and a reflective cylinder.
In night the gadget falls back on batteries charged with solar panels to light LED bulbs installed in homes. Poor families can buy this gadget for Rs 1,100 after subsidy. If the government approves the additional subsidy of Rs 500 crore, then the cost of the gadget for the poor will come down to Rs 600, Chaudhuri said. The sunlight-capturing gadget has one lower dome like a bowl, the upper side of which is attached to a reflective cylinder. The upper end of the cylinder is attached to another dome, which is a transparent semi-spherical object like a transparent inverted bowl. It captures daylight throughout the day even when the sun is low and passes it down through the tube with a thin layer of mirrorlike reflective coating. The lower dome spreads the light across the room. The upper dome, the solar panels and part of the cylinder remains on the roof.
Part of the cylinder, lower dome and batteries fitted with LED’s remain inside a room – on the ceiling. “This gadget is a mix of a solar dome to channelise sunlight during the day from roofs. At the same time a solar panel attached to the dome will charge a battery which will provide light during night. It can light up homes for at least 17 hours during summer and a minimum of 13 hours during winters. The batteries are good enough to hold charges and provide light for three nights,” Chaudhuri said. “The department of science and technology has recently invited expression of interest for manufacturing these gadgets and almost 30 manufacturers from 13 states have been shortlisted. They will now be trained to manufacture this model of micro solar dome,” he said.
Chaudhuri said the gadgets will be distributed through state agencies and non-government organisations working in slums. “The initial plan is to distribute one crore gadgets in two years,” he said. The pilot project for the scheme has already distributed a few thousand of these gadgets at slums in Mumbai’s Pawai area, in slums in Delhi, Guwahati, Tripura and Kolkata. Renewable Energy College is also working on a version of this gadget that can be plugged to the grid during night for shanties that have access to power supply sources.