'Liters of light' shining in Cameroon slums


A common characteristic of informal settlements in Cameroon is the lack of indoor lighting during the day. Because of security concerns, the sizes of windows are kept to a minimum. This prevents the use of natural daylight, leaving indoor spaces in darkness. To carry out any productive activities, households have to turn on the lights – for those who can afford electricity - or use kerosene lamps or candles adding to their electricity consumption and accompanying energy-related expenses as well as indoor air pollution. The lack of sufficient ambient lighting during the day hampers the ability to carry out household chores and other important tasks. To help communities in dealing with this frustrating situation, Fondation Camerounaise de la Terre Vivante FCTV (a non-profit making Cameroonian environmental association), in partnership with Noble Energy Cameroon Ltd, and UN-Habitat has been promoting a clean lighting daytime technologies, called liters of light or “bouteille de lumière” under the solar bulb Project.

What is it?









This gadget is an innovative passive lighting technology based on a transparent plastic bottle filled with clean water. It is fitted into the corrugated iron roofs of houses without ceilings found in informal settlements.

How to install it?

On installation, one-third of the bottle is left outside the roof while the remaining two-thirds protrudes into the house. Sealant, rivets, and putty are applied around the bottle and the roof to ensure that it remains weatherproof. When properly installed, the water inside the bottle with its refractive properties produces a light similar to a normal electric light bulb. A small amount of bleach is added to the water to ensure that it is kept clear and free from algae and that high quality light is produced for a long time.

Case studies – Data from the Solar Bulb Project

More than 3,000 solar bulbs are successfully being used in slums in Yaoundé and Douala (Cameroon) by over 700 households. These are contributing to enhance their productivity, reduce their energy fees - up to US $3 per month saved on their electricity bills - as well as improvements in air pollution. These households are contributing to reduce CO2 emissions by 170 Kg per day.