metal lock to prevent it from slipping. It is then embedded into a corrugated iron roof. A small part of the bottle is left outside while the rest of it protrudes into the house. Sealant is put around the hole made in the roof to keep it weather proof. The refractive properties of water ensures that the light from the sun that reaches the inside of the bottle becomes omni-directional mimicking an electric light bulb and emitting the same amount of light as a 40–60 W incandescent bulb depending on the amount of solar insolation available. Adding bleach to the water prevents it from turning green with algae and ensures a high quality light keeping the water clear for a longer time. In order to facilitate use of the invention through open source mechanisms, step-by-step guides on materials and installation are available online. Glue Using an appropriate durable, leak-proof, space-filling glue, that does not melt because of the sun, is one of the main challenges for the solution. Many local groups are experimenting with different glues to find the best solution for both costs and quality. It was usually found that silicone-based or polyurethane glues work best. The inventor, Alfredo Moser, used a polyester resin. Countries Argentina A local project is underway. Bangladesh Liter of Light Bangladesh was started by Shanjidul Alam Seban Shaan under Lights Foundation in 2015 in Chittagong. They made a local version of the bottle light called 'Botol Bati', which costs around $2–2.50 USD and lasts for 4–5 years. They aim to spread awareness of bottle lights to remote areas by training local school students. Around 45% of Bangladeshi people have no access to electricity, and around 24% of the total population live in slums where people use illegal electricity. Lights Foundation's aim is to serve those people. Liter of Light Bangladesh started spreading the idea in New York and other states. Brazil In Brazil, everything started in December 2012, when two Brazilians named Alanna Sousa and Pedro Santos decided to implement the Liter of Light project in Brazil. By 2013, Vitor Belota, coincidentally Alanna's neighbor, had the same impetus to bring Liter of Light to Brazil after learning about the project in Kenya. The trio met and carried out a pilot project, where the first daytime solutions were installed in two communities in Santa Catarina. In 2015, seeing that the context of the Brazilian communities