En esta noticia
Placing a plastic bottle filled with water on a house roof is a low-cost trick used in different countries to make use of natural light.
The method, known as the Moser lamp, originated in Brazil and later spread to communities in more than 30 countries. It works by using the refraction of sunlight through water to spread light inside homes.
How does placing a plastic bottle filled with water on the roof work?
Placing a clear plastic bottle filled with water on a house roof is a natural lighting technique. Its goal is to use sunlight to light rooms that are dark during the day, without needing electricity.
The system consists of installing a PET bottle, usually a two-liter one, through an opening in the roof. Part of the container is exposed to the outside to receive sunlight, while the other part extends into the home.
When sunlight passes through the bottle, the water changes its path and helps spread the light in different directions inside the room. To keep the water clear, a small amount of bleach can be added to help prevent algae and microorganisms from growing.
What is the origin of the trick of placing a plastic bottle filled with water on the roof?
The technique was developed in the early 2000s by Alfredo Moser, a Brazilian mechanic from the city of Uberaba, in the state of Minas Gerais.
The idea emerged amid power-supply problems in Brazil. Faced with blackouts and the need to light rooms during the day, Moser looked for a low-cost alternative that did not depend on the power grid.
The initiative gained broader international reach in 2011, when the MyShelter Foundation brought the idea to the Philippines through the Liter of Light program. During its first 20 months, it was implemented in more than 150,000 Filipino homes and reached about 350,000 homes across 15 countries. Over time, it spread to more than 30 countries.
What are the benefits of placing a plastic water bottle on the roof?
The Moser lamp offers an affordable lighting alternative for homes and workplaces that struggle to make use of natural light.
Its main benefits include:
- Reduces electricity use: it lights rooms during daylight hours without turning on electric bulbs.
- Low installation cost: it uses accessible materials, such as a clear PET bottle and water, with no electronic components needed.
- Reuses plastic materials: it makes use of bottles that might otherwise become waste.
- Improves lighting in dark spaces: it can be used in rooms without enough windows, warehouses, interior hallways and small workshops.
- No electrical connection needed: it works directly with sunlight, so it can be useful in communities with limited or unreliable access to electricity.
Before installing it, it is recommended to assess the condition of the roof, as it is necessary to drill through it and properly seal the bottle edges to prevent water leaks.