In 2002, Alfredo Moser a Brazilian mechanic had a light-bulb moment and came up with a way of illuminating his house during the day without electricity - using nothing more than plastic bottles filled with water and a tiny bit of bleach.
In the last three years his innovation has spread throughout the world and now in millions of homes.
Each bottle averages an equivalent
output of a 50 watt bulb.
For humans, sunlight and vitamin D is critically important for the development, growth, and maintenance of a healthy body, from birth until death.
We need natural
light at all times during the day to help
improve our mood and health.
Simple refraction of sunlight, explains Moser, as he filled an empty two-liter plastic bottle.
Wrapping his face in a cloth he makes a hole in a roof tile with a drill. Then, from the bottom upwards, he pushes the bottle into the newly-made hole.
The inspiration for the "Moser lamp" came to him during one of the country's frequent electricity blackouts in 2002.
Moser and his friends began to wonder how they would raise the alarm, in case of an emergency, such as a small plane coming down, imagining a situation in which they had no matches.
His boss at the time suggested getting a discarded plastic bottle, filling it with water and using it as a lens to focus the sun's rays on dry grass. That way one could start a fire, as a signal to rescuers.
This idea stuck in Moser's head - he started playing around, filling up bottles and making circles of refracted light.
Soon he had developed the lamp.
Moser has installed the bottle lamps in neighbors' houses and the local supermarket. While he does earn a few dollars installing them, it's obvious from his simple house and his 1974 car that his invention hasn't made him wealthy.
What it has given him is a great sense of pride.
Carmelinda, Moser's wife of 35 years, says her husband has always been very good at making things around the home, including some fine wooden beds and tables.
But she's not the only one who admires his lamp invention. Illac Angelo Diaz, executive director of the MyShelter Foundation in the Philippines, is another.
MyShelter specializes in alternative construction, creating houses using sustainable or recycled materials such as bamboo, tyre and paper.
Following the Moser method, MyShelter started making the lamps in June 2011. They now train people to create and install the bottles, in order to earn a small income.
In the Philippines,
where a quarter of the population lives below
the poverty line, and electricity is unusually
expensive, the idea has really taken off, with
Moser lamps now fitted in 140,000 homes.
The idea has also caught on in about 15 other countries, from India and Bangladesh, to Tanzania, Argentina and Fiji.
Diaz says you can find Moser lamps in some remote island communities.
People in poor areas are also able to grow food on small hydroponic farms, using the light provided by the bottle lamps, he says.
Overall, Diaz estimates, one million people will have benefited from the lamps by the start of next year.
Did Moser himself imagine that his invention would have such an impact?