Solar Bottle Bulbs Light Up Dark Homes

By David South, Development Challenges, South-South Solutions

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More than 1.7 billion people around the world have no domestic electricity supply, of whom more than 500 million live in sub-Saharan Africa (World Bank). Without a source of electricity, it is difficult to use conventional technology to switch the lights on.

While it is possible to run lights using batteries or diesel generators, these are expensive options that are not possible for many poor people. The more of a slim income that is spent on light, heat or cooking fuel, the less there is left for better-quality food, clothing, transport or education and skills development.

Low-cost light is great, but free light is even better – and one Brazilian solution is offering this.

Brazilian innovator and mechanic Alfredo Moser has taken the common plastic water bottle and created a low-cost lighting solution for dark spaces. Often makeshift homes lack decent lighting or a good design that lets the light in during the day. This means it may be a bright, sunny day outside, but inside the home or workplace, it is very dark and reading or working is difficult.

Moser came upon the idea during regular blackouts in his home city of Uberaba ( in southern Brazil during 2002. During the blackouts, only factories were able to get electricity, leaving the rest of the population in the dark.

The “Moser Light” involves taking plastic bottles, which are usually just thrown away or recycled, and filling them with water and bleach to draw on a basic physical phenomenon: the refraction of sunlight when it passes through a water-based medium.

It is a simple idea: Holes are drilled in the ceiling of a room and the bottles placed in the holes. The liquid-filled bottle amplifies the existing sunlight (or even moonlight) and projects it into the dark room. This turns the plastic bottle into a very bright lightbulb that does not require any electricity.

Moser uses a solution of two capfuls of bleach added to the water to prevent anything growing in the water such as algae because of the exposure to sunlight.

“The cleaner the bottle, the better,” he said.

Polyester resin is used to seal the hole around the plastic bottle and make it watertight from rain.

Moser claims his bottle innovation can produce between 40 and 60 watts of light.

Moser uses recycled plastic bottles, so the carbon footprint is minimal compared to the manufacture of one incandescent bulb, which takes 0.45 kilograms of CO2 (UN). Running a 50 Watt incandescent light bulb for 14 hours a day for a year, around the same light as produced by the bottle bulb, produces a carbon footprint of nearly 200 kilograms of CO2.


The plan is to try and get as many as a million homes fitted with the lighting system by the end of 2013.

In many poor areas, it is common to live in makeshift or rudimentary dwellings. These are often built to crude designs and, in order to keep costs down and boost security, will have few or no windows. These dwellings will consequently be very dark inside, even on the brightest days. This leaves people having to turn to a source of artificial light if they want to do something indoors like read or work. And this costs money. Be it electricity from a mains, or battery-powered lamps or gas-powered lanterns, the cost will eat into a person’s tight income. This is where Moser’s simple solution saves the day and saves pennies: it is free light once the bottle lamp system is installed.

Placing the bottle lights in the ceiling transforms the ceiling into something akin to the night sky, with many points of light shining down into the room like stars. It also means the occupant of the room does not just have to strain to see with the use of a single light but now has many lights illuminating the room from all angles.

“It’s a divine light,” Moser told the BBC World Service. “God gave the sun to everyone, and light is for everyone. Whoever wants it saves money. You can’t get an electric shock from it, and it doesn’t cost a penny.”

It has not been a road to riches for Moser. He has made some money installing the system in a local supermarket and nearby homes, and he has inspired a charity to install the lighting system and to train people to do the installation and make an income from it.

The MyShelter Foundation in the Philippines was inspired by Moser’s invention and has installed the system in some 140,000 homes there, the BBC reported.

“We want him to know that there are a great number of people who admire what he is doing,” MyShelter Executive Director Illac Angelo Diaz said of Moser.

Using bottle bulbs instead of electricity or generators means families can save US $6 per month, according to Diaz (CNN). The Philippines is reported to have the most expensive electricity in Asia and slum homes usually do not have electricity.

It is estimated 15 other countries also have homes using the Moser system. The MyShelter Foundation believes 1 million homes worldwide have used the Moser system as of 2013.

Liter of Light (, run by the MyShelter Foundation, offers instructions on how to install the lighting system on its website.


1) D-Lab: MIT: Development through Dialogue, Design and Dissemination: D-Lab is building a global network of innovators to design and disseminate technologies that meaningfully improve the lives of people living in poverty. The program’s mission is pursued through interdisciplinary courses, technology development, and community initiatives, all of which emphasize experiential learning, real-world projects, community-led development, and scalability. Website:

2) d.light Solar: d.light is a for-profit social enterprise whose purpose is to create new freedoms for customers without access to reliable power so they can enjoy a brighter future. d.light design manufacture and distribute solar light and power products throughout the developing world. Website:

3) Liter of Light:  It brings the eco-friendly bottle light to communities living without electricity. Website:

4) Solar Sister: Solar Sister eradicates energy poverty by empowering women with economic opportunity.  They combine the breakthrough potential of solar technology with a deliberately woman-centered direct sales network to bring light, hope and opportunity to even the most remote communities in rural Africa. Website:

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