Updated on December 31, 2023


Created on August 6, 2016

Deciwatt GravityLight

Upcoming Update

A gravity-powered LED lamp.

Developed By
  1. Deciwatt
Tested By
  • Deciwatt
Content Partners
  1. Siemens | Stiftung


Product Description

GravityLight is a gravity-powered lamp designed by Deciwatt for use in developing or third-world nations as a replacement for kerosene lamps. It uses a bag filled with rocks or earth, attached to a cord, which slowly descends similar to the weight drive in a cuckoo clock. This action powers the light for up to thirty minutes. With neither batteries nor need for the sun, the lamp provides light instantly, can be stored indefinitely and used in many different environments.

There are currently two models of GravityLight supported by Deciwatt, the GL01 and GL02.

Target SDGs

SDG 7: Affordable and Clean Energy

Market Suggested Retail Price


Target Users (Target Impact Group)

Household, Public Sector Agencies, NGOs

Distributors / Implementing Organizations

Deciwatt and Gravity Light Kenya Ltd

Competitive Landscape

Direct competitors include Crush Light, Consol Solar Jar, and MPOWERD Luci Original.

Manufacturing/Building Method

Mass produced in Kenya

Intellectural Property Type


User Provision Model

The lamp is distributed through local distribution networks, partners and sales agents (door-to-door networks, farmer groups, and more traditional market stalls). International distribution is handled by various international partners listed on the GravityLight webpage.

Distributions to Date Status

Distribution started in December 2016, with about 140 products being made each day in Kenya. Within 3 years of launch they plan to have sold 450,000 GravityLights.

Design Specifications

Specifications for the GL01 and GL02 models:

Product Schematics

Technical Support

A toll-free support line via SMS or over the phone Deciwatt also provide an support webpage, with links to installation guides, instruction manuals and other relevant documentation.

Replacement Components



Lifecycle: GL01 model: 3 months - 1 year of continuous use GL02 model: >3 years of continuous use The GL02 also comes with a 1 year warranty.

Manufacturer Specified Performance Parameters


Pull the cord for instant light
One lift creates 20 minutes of light
Totally weather independent
No battery or external power required GL02 has 50% greater efficiency than and 12 times the lifespan of the GL01.
The product is designed to pay for itself within 3 months, saving families an average of 70 USD per annum.

Vetted Performance Status

Testing performed by the manufacturer found that the GL02 has a lifecycle of >3 years of continuous use on their testing rig, however no third-party testing has been performed.


The GL02 instruction manual includes the following safety advice, due to the heavy weight of the bag: GravityLight suspends the bag from a pulley, which reduces the strain on the cord and the gearing. This device complies with part 15 of the FCC Rules in not producing harmful interference.

Complementary Technical Systems

Possibility to add additional SatLights (connected light points) which can be daisy- chained around the room and used as task lights.

Academic Research and References

Anonymous, 2013, Gravity Light. Appropriate Technology, 40(4), pp. 60-61.

Blackley, S., & Sheffield, R., 2016, Environment: Re-negotiating the E in STEM Education. ECO-THINKING, 1.

Sahota, J., 2017, GravityLight. Alternatives Journal, 43(2), pp.12-12.

Yakubu, Y.F., 2017, GravityLight in Nigeria. Energy Planning and Analysis Department, Energy Commission of Nigeria.

Deciwatt – Remarkable Renewable Energy Products. n.d. Deciwatt.global.

GravityLight 2: Made in Africa. n.d. Indiegogo.

Turning Gravity into Light. n.d. www.shell.com.ph.

Support. n.d. Deciwatt global.

Deciwatt Ltd. 2014. GravityLight – GL01 Specifications. Deciwatt.global. Deciwatt.

Deciwatt Ltd. n.d. GravityLight – GL02 Specifications. Deciwatt.global. Deciwatt.

Deciwatt Ltd. n.d. GL02 Inventors Pack. Deciwatt.global. Deciwatt.

Deciwatt Ltd. n.d. GL02 Instruction Manual. Deciwatt.global. Deciwatt.

Deciwatt Ltd. 2017. GL02 Declaration of Conformity. Deciwatt.global. Deciwatt.

Hossen, Md. Shahed, Md. Tazul Islam, and Sabir Hossain. 2015. Design and Fabrication of a Gravity Powered Light. In International Conference on Mechanical Engineering and Renewable Energy 2015 (ICMERE 2015). Chittagong, Bangladesh: ICMERE 2015.

Compliance with regulations

Deciwatt's Declaration of Conformity for the GravityLight highlights all of the regulations it complies with in various jurisdictions. These include: CE, General Product Safety Directive 2001/95/EC, EMC Directive 2014/30/EU, IEC/EN/BS 55015, IEC/EN/BS 61547, IEC/EN/BS 61000-3-2, IEC/EN/BS 61000-3-3, IEC/EN/BS 62493, IEC/EN/BS 62471, RoHS Directive 2011/65/EU, WEEE Directive 2012/19/EU, IEC/EN/BS 60598-1, IEC/EN/BS 60598-2-4, FCC Part 15

Evaluation methods

GravityLight is tested in the Deciwatt workshop and out in the field. The GL02 Inventors’ Pack describes some aspects of the testing process, including their custom built Accelerated Life Testing rig. In 2014, it was tested in 1000 households across 26 countries to assess functionality and ease of use

Other Information

GravityLight was called one of The 25 Best Inventions of the Year 2013 by Time Magazine. Operating the GravityLight: 1. The user fills the bag with 12kg of heavy objects such as rocks or sand 2. The weight is lifted by pulling down on a bead cord. On release, the weight falls very slowly, transforming potential energy into kinetic energy as it powers a drive sprocket, which rotates very slowly with high torque 3. A polymer gear train running through the product turns this input into a high speed, low torque output that drives a DC generator at thousands of rotations per minute 4. It generates just under a tenth of a watt, to power an onboard LED and ancillary devices. GravityLight has a DC jack where auxiliary lights (SatLights) and other devices, such as a radio, can be attached 5. Once the weighted bag reaches the floor, which depends on how high it was installed, it is simply lifted to repeat the process A pulley system is included, so users of any height or strength can lift the bag right up to the top - giving the maximum drop time. The 2 SatLights as additional light points connected to the main unit are included with the GravityLight.

Leave a Reply

Explore similar solutions


December 27, 2023

AEST Agricultural Waste Charcoal Briquettes

Read Solution

Implemented by

Appropriate Energy Saving Technologies Limited (AEST)


January 24, 2024

Bornay Inclin 600

Read Solution

Implemented by



December 22, 2023

Chispa Hogar

Read Solution

Implemented by

Soluciones Analíticas


January 8, 2024

EcoZoom Jet

Read Solution

Implemented by



January 20, 2024

Flexigester V10

Read Solution

Implemented by

Sustainable OneWorld Technologies C.I.C. (SOWTech)


December 16, 2023

HPS Biomass Gasification Power Plant

Read Solution

Implemented by

Husk Power Systems (HPS)


January 21, 2024


Read Solution

Implemented by



February 1, 2024

Kenyan Domestic Ceramic Jiko Stove

Read Solution

Implemented by

Kenya Energy and Environment Organisations (KENGO)


January 16, 2024

Living Water Treatment Systems

Read Solution

Implemented by

George Greene III, PE, PhD


December 17, 2023

PP20 Power Pallets

Read Solution

Implemented by

All Power Labs

All Solutions

Contribute to E4C's Library of Breakthrough Sustainable Development Technology Solutions

Suggest A Solution

Get more information about Solutions Library and its features.

Learn More

Have thoughts on how we can improve?

Give Us Feedback

Join a global community of changemakers.

Become A Member