Alfredo Moser (* 1951 in Itajaí) is a Brazilian mechanic, and the inventor of the solar bottle bulb, known also as the ‘Moser Lamp’, or the PET bottle lamp.^[1][2] His invention led to the creation of the open-source organization Liter of Light, which offers sustainable lighting to families without electricity access in numerous countries worldwide.^[3]

Moser was born in rural Santa Catarina in 1951 and began his life working as a farmhand.^[4] He later moved to Brasília, where he worked as an auto mechanic. In 1978, he married his wife Carmelinda and then moved to Minas Gerais, settling with his family in Uberaba by 1980.^[5]

According to Moser, his inspiration for the invention emerged as a DIY solution in response to the blackouts during the 2001–2002 Brazilian energy crisis. However, the idea dates back to the late 1970s when he was working as a car mechanic for a telecommunications company in Brasília. On one occasion, imagining a scenario where a small plane might crash in the Amazon, he discussed with his boss the challenge of not having means like a matchbox to start a fire, given the long rescue times in that region. His boss then explained that filling a plastic bottle with water and placing it on dry grass would cause the water to act as a lens, concentrating the sun's rays, which could serve as a signal for potential rescuers. The explanation remained with Moser, influencing his later invention.^[6]

In the early 2000s, while working in his house, Moser began some tests by installing water-filled bottles on the roof of an unlit room in his home. Noticing that sunlight refracting through these bottles effectively brightened the otherwise dim room, he improved his next experiments using bleach and polyester resin.^[7]

After publicizing his invention, Moser was invited to speak at educational conferences. His invention was later embraced by open-source organizations like the MyShelter Foundation in the Philippines and has been replicated since 2012 through the Liter of Light project, which distributes sustainable lighting across multiple countries, benefiting impoverished communities lacking means or access to electricity. The project has further developed a method based on Moser's original invention, utilizing solar panels to power the bulbs. These panels are used in domestic installations and to illuminate streetlights throughout the night.^[8]

In 2011, Illac Angelo Diaz, Executive Director of the MyShelter Foundation, reported that Moser's invention was in use in approximately 140,000 homes in the Philippines alone. Additionally, residents in impoverished areas were able to cultivate crops on small hydroponic farms using the light provided by these bottle lamps.^[9] By 2014, Liter of Light had installed Moser lamps in over a million homes worldwide and expanded its reach across the Americas, Europe, Asia, and Africa by 2017.^[10]

Moser's lamp functions without external power, using a plastic bottle filled with chlorinated water inserted into a hole in the roof. The light is refracted and scattered, providing illumination comparable to a 40 to 60 watt incandescent bulb when sunlight strikes the bottle.^[11]

• This article draws heavily on the corresponding article in the Spanish-language Wikipedia, which was accessed in the version of 9/2013.