Liter of Light is an
open source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
design for a low-cost
light tube
Light tubes (also known as solar pipes, tubular skylights or sun tunnels) are structures that transmit or distribute natural or artificial light for the purpose of illumination and are examples of optical waveguides.
In their application to ...
(or
deck prism
A deck prism, or bullseye, is a prism (optics), prism inserted into the deck of a ship to provide light down below.
For centuries, sailing ships used deck prisms to provide a safe source of natural sunlight to illuminate areas below deck (ship), ...
or
vault light
Pavement lights (UK), vault lights (US), floor lights, or sidewalk prisms are flat-topped walk-on skylights, usually set into pavement (sidewalks) or floors to let sunlight into the space below. They often use anidolic lighting prisms to throw t ...
) that refracts solar light to provide daytime interior lighting for dwellings with thin roofs.
Daylighting Daylighting can refer to:
* Daylighting (architecture), use of windows for indirect lighting
* Daylighting (intersections), improving road visibility at intersections
* Daylighting (streams), restoration of a previously buried watercourse
* Dayl ...
is cheaper than using indoor electric lights during the day. The device is simple: a transparent
two-liter bottle
The two-liter bottle is a common container for soft drinks, beer, and wine. These bottles are produced from polyethylene terephthalate, also known as PET plastic, or glass using the blow molding process. Bottle labels consist of a printed, tight- ...
is filled with water plus a little bleach to inhibit
algal growth and fitted into a hole in a roof. The device functions like a
deck prism
A deck prism, or bullseye, is a prism (optics), prism inserted into the deck of a ship to provide light down below.
For centuries, sailing ships used deck prisms to provide a safe source of natural sunlight to illuminate areas below deck (ship), ...
: during
daytime
Daytime or day as observed on Earth is the period of the day during which a given location experiences Daylight, natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the ...
the water inside the bottle refracts sunlight, delivering about as much light as a 40–60 watt
incandescent bulb
An incandescent light bulb, also known as an incandescent lamp or incandescent light globe, is an electric light that produces illumination by Joule heating a filament until it glows. The filament is enclosed in a glass bulb that is either ...
to the interior. A properly installed solar bottle can last up to 5 years.
History

The use of plastic bottles in this way to provide indoor lighting from daylight was developed by
Alfredo Moser
Alfredo Moser ( 1951/1952 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. His invention led to the creation of the open-source organization Liter of Li ...
of Brazil. Using the technology as a social enterprise was first launched in the Philippines by Illac Diaz under the My Shelter Foundation in April 2011.
In order to help the idea to grow sustainably, Diaz implemented a "local entrepreneur" business model whereby bottle bulbs are assembled and installed by local people, who can earn a small income for their work. Within months, the organization expanded from one carpenter and one set of tools in one community in San Pedro, Laguna to 15,000 solar bottle bulb installations in twenty cities around the Philippines, and began to inspire local initiatives around the world.
MyShelter Foundation also established a training center that conducts workshops with youth, business companies, and other groups who are interested in volunteering their time to build lights in their communities.
In less than a year since inception, over 200,000 bottle bulbs were installed in communities around the world. Liter of Light had a goal to light up 1 million homes by the end of 2015.
Technology description

The Solar Bottle Bulb, as it has also been called, is installed in the roof of homes with the purpose of refracting sunlight in order to light up a room. The project's innovation lies in its utilization of cheap, durable and readily available materials to produce high quality natural lighting enabling the urban poor to have access to an affordable, environmentally friendly long-term alternative to electric light for use during the day.
1.5-liter bottles are the size most commonly reused for lighting. After being filled with water and a little bleach, the bottle is pushed through a steel sheet that serves as a metal lock to prevent it from slipping. It is then embedded into a corrugated iron roof. A small part of the bottle is left outside while the rest of it protrudes into the house. Sealant is put around the hole made in the roof to keep it weather proof. The refractive properties of water ensures that the light from the sun that reaches the inside of the bottle becomes omni-directional mimicking an electric light bulb and emitting the same amount of light as a 40–60 W incandescent bulb depending on the amount of solar
insolation
Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
Solar irradiance is measured in watts per square metre ...
available. Adding bleach to the water prevents it from turning green with algae and ensures a high quality light keeping the water clear for a longer time. In order to facilitate use of the invention through open source mechanisms, step-by-step guides on materials and installation are available online.
Glue
Using an appropriate durable, leak-proof, space-filling glue, that does not melt because of the sun, is one of the main challenges for the solution. Many local groups are experimenting with different glues to find the best solution for both costs and quality. It was usually found that
silicone
In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...
-based or
polyurethane
Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...
glues work best. The inventor, Alfredo Moser, used a
polyester resin
Polyester resins are synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Maleic anhydride is a commonly used raw material with diacid functionality in unsaturated polyester resins. Unsaturated polyester r ...
.
Rigid glass bottles are also used,
and may be easier to caulk than flexible plastic bottles. Some caulks react chemically with plastic, slowly making it brittle. Silicone caulks can chemically bond to glass bottles, which may improve bond durability.
Countries
Argentina
A local project is underway.
Bangladesh
Liter of Light Bangladesh was started by Shanjidul Alam Seban Shaan under Lights Foundation in 2015 in
Chittagong
Chittagong ( ), officially Chattogram, (, ) (, or ) is the second-largest city in Bangladesh. Home to the Port of Chittagong, it is the busiest port in Bangladesh and the Bay of Bengal. The city is also the business capital of Bangladesh. It ...
. They made a local version of the bottle light called 'Botol Bati', which costs around $2–2.50 USD and lasts for 4–5 years. They aim to spread awareness of bottle lights to remote areas by training local school students. Around 45% of Bangladeshi people have no access to electricity, and around 24% of the total population live in slums where people use illegal electricity. Lights Foundation's aim is to serve those people. Liter of Light Bangladesh started spreading the idea in New York and other states.
Brazil

In Brazil, everything started in December 2012, when two Brazilians named Alanna Sousa and Pedro Santos decided to implement the Liter of Light project in Brazil. By 2013, Vitor Belota, coincidentally Alanna's neighbor, had the same impetus to bring Liter of Light to Brazil after learning about the project in Kenya. The trio met and carried out a pilot project, where the first daytime solutions were installed in two communities in Santa Catarina.
In 2015, seeing that the context of the Brazilian communities and also the needs were different, Litro de Luz Brasil (Liter of Light Brazil) started working with the nighttime street light, carrying out its first installation action in June of the same year, in the Vila Beira-Mar Community, located in Rio de Janeiro.
Today, Litro de Luz Brasil is established as a non-profit organization and since then has directly impacted the lives of more than 20,000 Brazilians through more than 3,700 solutions, reaching more than 120 communities across the country.
China
Liter Of Light China was created by three international students from China in 2016, and the first project in
Rudong
Rudong County () is under the administration of Nantong, Jiangsu province, China, and lies on the Yellow Sea coast. It administers 14 towns and five districts. The 14 towns are Juegang, Matang, Fengli, Caobu, Chahe, Shuangdian, Xindian, Hekou, ...
will be conducted in the early summer, 2017.
Colombia
The movement in Colombia was started by Camilo Herrera in a small town called
Duitama
Duitama () is a city and municipality in the department of Boyacá. It's the capital of the Tundama Province. Duitama is located northeast of Bogotá, the capital of Colombia and northeast of Tunja, the capital of Boyacá. In 2023 Duitama had ...
in the
Boyaca Department, approximately 200 kilometers from
Bogota. After launching a pilot in Bogota in collaboration with Liter of Light Switzerland in February 2012, a local Bogota organization was created. The first bottles in Bogota were installed in the areas of
Divino Niño
The Divino Niño, also known as Divino Niño de Bogotá or Divine Child Jesus, is a 20th-century religious wooden statue of the child Jesus originating from Bogota, Colombia. A cross originally in the back was removed upon purchase by Father G ...
and La Colina of Ciudad Bolívar. The volunteers in Bogota are also working closely with
Un Techo Para Mi Pais
TECHO, also known as Un Techo para mi País (UTPMP) (Spanish language, Spanish for "A Roof For My Country"), is a nonprofit organization that mobilizes youth volunteers to fight extreme poverty in Latin America, by constructing transitional housi ...
to identify areas in need.
Dominican Republic
Liter of Light was started up in the Dominican Republic by the German volunteer Nicolai Rapp in 2015 who then distributed the project with other German and local volunteers in over 7 provinces.
They achieved the installation of bottle and solar nightlights in more than 1000 houses with global fundraising. In the focus of their movement are the rural areas without or with limited access to electricity.
They also presented the idea of Liter of Light to several local NGO's in seminars and workshops to reach all the off-grid communities of the country. Recently, their efforts also focused on bringing
the project to Haiti, where around 75% of the population has to live without access to electricity.
Egypt
A group of seven students from the French University in Egypt (UFE) have begun Liter of Light locally in the context of a social and environmental development project.
In November 2014, PepsiCo announced that they will implement Liter of Light in 3 villages in upper Egypt, with two partners : SunUtions Company for solar solutions and Masr ElKheir organization.
France
In 2015, Liter of Light France was created. The French branch is developing an important link between pedagogical project in Europe and the international cooperation around the world. The NGO wants in Europe to make the new generation aware of the
energy poverty
In developing countries and some areas of more developed countries, energy poverty is lack of access to modern energy services in the home. In 2022, 759 million people lacked access to consistent electricity and 2.6 billion people used dangerous a ...
reality and show that they can have, with a small activity, a huge social and environmental impact. The NGO wants, as well, to deliver the message to developing countries that a new generation all around the world are caring about the World Citizenship. During International cooperation, Liter of Light France is underlining the main philosophies of the movement as technological innovation accessible to everybody, capacity building, and initiatives South-South. The movement in France was started by Olivier Lasbouygues, Paola Sierra and Isabel Rico.
India
Inspired by the project of Isang Litrong Liwanag, Liter of Light was introduced to the people of India by Pradeep Chanti. The first trial was done in Vikarabad, a rural village in Telangana in 2011. With this experience, the team gradually expanded the concept. Later, Mr. Ranjeet Gakhare, an alumnus of Indian Institute of Technology Bombay, Ms. Bhavana Poppoppu and Mr. Chaitanya Reddy from Cornell University joined Pradeep and expanded the concept all over India. With the generous help of several NGOs and various organizations, awareness campaigns and workshops were conducted in various cities like Hyderabad, Mumbai, Chennai, Kolkata, Jalpaiguri, and Delhi. Starting with the one bottle in Vikarabad, the team is not only installing several models in houses of the unprivileged, but also mentoring various other organizations, NGOs, student bodies and the people in need. The demonstration of Liter of Light was conducted at TEDxChristUniversity in November 2012. In 2014 it was carried out by Desire Foundation, Bhubaneswar on the coruscating day of Diwali to celebrate the festival of light in a unique style with the underprivileged.
Kenya
A youth group called Koch Hope has started to install 2 L PET bottles in the Korogocho slums.
At first the people were skeptical that the bottle installations would let in water, so the first bottles were installed in a local school as a test. The locals thus bought into the idea and the first 100 bulbs were installed in April 2011 for free in hopes to attract interest and donors. Next, the local initiative would like to expand to other areas around Nairobi.
Malaysia
Liter of Light Malaysiaran its first project in June, 2015, and is run by a Malaysia-based social business calle
Incitement founded by Zikry Kholil and Daniel de Gruijter, which runs several social initiatives. Liter of Light Malaysia has thus far completed 36 projects, predominantly for marginalized communities in Pahang, Malaysia and the Orang Asli communities living in Cameron Highlands, but also in Sabah and Sarawak in East Malaysia (Borneo). After Incitement launched Liter of Light Malaysia, it has also pushed Liter of Light into the Italian market under the umbrella of Incitement Italy. To date, Liter of Light Malaysia has installed 1850+ solar powered lamps in the rural areas of Malaysia, effectively providing light at night for more than 6,000 underprivileged Malaysians.
Mexico
Liter of Light began in Mexico in early 2013, sponsored by Qohélet A.C. Founded by Tere Gonzalez, who had previously worked with Liter of Light in India & Spain, the group began operations with a pilot program in the state of Chihuahua México, where they were able to benefit 114 people. As of September 2013, they are working to complete the next phase of installations in Ajusco, Mexico City, to benefit a further 500 families.
Nepal
"Ujyalo" means "the light" in Nepali. Project Ujyalo creates bottle lights, inspired by the Liter of Light initiative. It was started by the Ujyalo Foundation in Nepal.
Netherlands
Liter of Light Netherlands aims at realizing projects in suitable countries with the purpose of establishing a local Liter of Light sub-organization. Its work is threefold: Prior to the project, the work focuses mainly on gathering information, preparing the projects, promoting and fundraising. During the projects abroad, the project focuses on spreading the idea and inspiring people to get involved with Liter of Light and even starting their own project. Therefore, empowering the partner organization is a major goal and includes holding bottle-building workshops on site and setting up an operational framework. After the project, the partner organizations will be assisted and continuously supported by Liter of Light Netherlands.
Pakistan
A partnership has been created with Ace Welfare Foundation, Pakistan. According to both of the organizations' objectives, and considering the fact that more than 11% of the Pakistani population lives without access to the electricity, including 50,000 villages that are completely separate from the national grid, it was decided to form a partnership in order to implement the Liter of Light project.
Panama
A local project is underway.
Peru
A local project is underway.
Philippines
The solution was first launched in the Philippines by Illac Diaz under the MyShelter Foundation.
As of July 2011, the organization had installed 10,000 bottles in the Philippines
and shortly thereafter reached 15,000 installations
and their goal for 2012 is to reach 1 million homes.
In order to help the idea to grow sustainably, they have implemented a “local entrepreneur” business model, whereby bottles are put together and installed by locals who can in turn earn a small income for their work. Additionally a Liter of Light office has been established that conducts volunteer workshops.
Spain
A local project is underway.
Switzerland
Liter of Light Switzerland began as a project of the SIMagination Challenge at the University of St. Gallen. The project grew and was established as a student club at the University of St. Gallen and as a non-profit organization in Switzerland in November 2011. The organization's first project was to plan and implement a pilot in Bogota together with Litro de Luz Colombia. The pilot took place in February 2012 and together they installed bottles in Ciudad Bolivar, Bogota. Throughout 2012, Liter of Light Switzerland undertook additional projects in Spain, India and Bangladesh.
The Swiss NGO plans to continue sharing lessons learned and spreading the concept via a global platform as well as launching more pilots around the world.
Tanzania
World Unite! in cooperation with local NGOs has started A Liter of Light in Tanzania in April 2013. Project locations are Dar es Salaam, Moshi/Kilimanjaro and Zanzibar.
Uganda
A local project is underway.
United States
Liter of Light USA is committed to educating and raising awareness of Liter of Light and its global outreach. The company is headquartered in New York and frequently holds events and workshops in Manhattan. It maintains its own social media pages on Facebook, Twitter, and LinkedIn.
Zambia
A local project is underway.
Awards and recognition
* 2014:The
World Habitat Award
The World Habitat Awards were established in 1985 by the Building and Social Housing Foundation as part of its contribution to the United Nations' International Year of Shelter for the Homeless in 1987.
Two awards are given annually to projects f ...
* 2015: The
Zayed Future Energy Prize
The ''World Future Energy Summit'' (WFES) is an annual event hosted in the United Arab Emirates, aiming to advance future energy, energy efficiency, and clean technologies. It began in 2008, held under the patronage of Sheikh Mohammed Bin Zayed A ...
* 2016: The
St Andrews Prize for the Environment
The St Andrews Prize for the Environment is a prestigious international environmental award funded and administered by the University of St Andrews in Scotland, United Kingdom. Prior to 2020, the American exploration and production company ConocoP ...
See also
*
Anidolic lighting
Anidolic lighting systems use nonimaging optics, anidolic optical components to light rooms. Light redirected by these systems does not converge to a Focus (optics), focal point or form an image, hence the name (from ''an'', without, and ''eidol ...
and
Daylighting Daylighting can refer to:
* Daylighting (architecture), use of windows for indirect lighting
* Daylighting (intersections), improving road visibility at intersections
* Daylighting (streams), restoration of a previously buried watercourse
* Dayl ...
, broader concepts
*
Deck prism
A deck prism, or bullseye, is a prism (optics), prism inserted into the deck of a ship to provide light down below.
For centuries, sailing ships used deck prisms to provide a safe source of natural sunlight to illuminate areas below deck (ship), ...
and
Vault light
Pavement lights (UK), vault lights (US), floor lights, or sidewalk prisms are flat-topped walk-on skylights, usually set into pavement (sidewalks) or floors to let sunlight into the space below. They often use anidolic lighting prisms to throw t ...
, older glass versions
*
Daylight redirecting film
*
Glass brick
Glass brick, also known as glass block, is an architectural element made from glass. The appearance of glass blocks can vary in color, size, texture and form. Glass bricks provide visual obscuration while admitting light. The modern glass block ...
References
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External links
* https://www.bbc.co.uk/news/magazine-23536914 Alfredo Moser: Bottle light inventor proud to be poor - BBC News Magazine 13 Aug 2013
* http://isanglitrongliwanag.org
* http://literoflightswitzerland.org/idea.html
* https://www.youtube.com/watch?v=xhtG5vW1lOw The Philippines: Bottleman (''UN in Action'' episode 1432)
Appropriate technology
International volunteer organizations
Charities based in the Philippines
Organizations established in 2013
Brazilian inventions
Organizations based in Manila