Technology has no meaning unless it is cheap and can touch the lives of poor, affected people.
One such technology that catches attention for being unique and an extremely simplistic solution is the solar water light bulb. It was first discovered in Brazil by Alfredo Moser in 2002. Scores of people have benefited from it and is a good solution for lighting up slums where even kerosene or candles is not affordable.
The technology is simple and consists of a plastic bottle filled with purified water and bleach (to prevent algal growth. Just hang it from the roof ceiling and seal it with some sealant to prevent rain water from coming in and that is it. It is being done in Philipines under the name- “Isang Litrong Liwanag,” which means a litre of light.
The bottle can provide as much light as a 50 watt bulb and can operate for up to two years without changing. Even on full moon nights, it can provide some light.