Raul Aaron David: What or who is the inspiration behind your ‘Litre of Light’ project - Roshni?

Roshni Sen: The predicament of the poor people living in the slums of our city was the inspiration behind Project Roshni. When my brother, Sabyasachi and I realised that even with bright sunlight outside, people living in the slums need to use electric bulbs during the day, we were drawn to find a solution for them.

RAD: Being a school student, what kind of support have you got from your school, be it your principal, teachers or classmates?

RS: The Principal of my school La Martiniere for Girls, Mrs Rupkatha Sarkar has been a staunch supporter of my work. She has given wide publicity to my work not only in my school but has organized several events where I presented this simple solution to students of other schools so that they could take it up themselves and help spread “light”.

RAD: The road to success is littered with hurdles, so what were the kinds of difficulties you faced while trying to implement Project Roshni?

RS: Upon searching for information on solar light options, my brother chanced upon an initiative by MIT students in the slums of the Philippines. They filled plastic bottles with water, added bleach to ensure that algae did not grow, cut a hole through the tin roofs of the slums and partially inserted the bottles. The sunlight refracted through the bottle into the room and produced light equivalent to a 40 W – 60 W bulb. The bottles lasted five years and the light cost nothing.

We knew that we had a solution but our excitement was short-lived when we realised that instead of tin roofs in the Philippines, which could be easily cut, the slums in Kolkata had brittle earthen tiles on their roofs and that would pose problems. My brother procured a dozen tiles and any attempt to cut a hole led to the tiles disintegrating. He kept tinkering with the tiles until he arrived at a solution. Marking the diameter of a bottle’s neck on the tile, he drilled holes along the marking and cut out extracts using a power drill. The bottle could then be easily inserted into this delicately-cut hole and fixed with a sealant.

RAD: Was there a point when the obstacles ahead of you seemed impossible to get around and you just wanted to throw in the towel?

RS: Not really. The smiles on the faces of the beneficiaries have more than made up for any difficulties.

Roshni and her brother with their Litre of Light lamps - adapted for Indian/Kolkata conditions.

RAD: Other than Project Roshni, do you have any other ideas in mind right now?

RS: To work on a solution to provide solar based light at night.

RAD: What is your annual goal for Project Roshni?

RS: We wish we could take it to 10,000 bottles per year. Between us (with brother) we have so far installed 177 sets.