Frequently Asked Questions

+ How does it work?

GravityLight is an innovative device that generates power using the force of gravity from a weight. Made up of three parts, the light is hung above the ground giving the weight component a 6ft drop. To power the light the weight is lifted, and on release starts to fall slowly back down towards the ground. This movement powers a series of gears which rotate very slowly with high torque (force). The gear train running through the product turns this input into a high speed, low torque output that drives a power generator at thousands of rotations per minute. This output is used to power an LED light, and ancillary devices, providing off-grid communities with access to energy.

+ How do I install my GravityLight?

Watch the GravityLight unboxing video or click here for the instruction manual.

If you have any issues with your GravityLight, please take a look at our troubleshooting page.

+ Can it power other things than light?

With the 0.1W of power it generates, GravityLight provides a light superior to kerosene lamps and can also power other devices, such as a radio. You will find a DC jack at the back for connecting SatLights and/or other devices. If you're experimenting we’d love to hear what you discover, so please email us at

+ What is the output of GravityLight?

To this question there are two answers: the power output of the GravityLight in Watts, and the light output of GravityLight in Lumens.

The power output of a 12.5kg load is 0.075W The Light output is 16 Lumens

The advantage of an LED light source over a kerosene lamp is that nearly all this light output can be directed at a task or onto a surface. This idea of ‘useful light’ requires a more appropriate unit of measure than ‘Lumens’ (total light output). Lux is the unit for light falling on a surface (lumens/square meter). For comparison, when used to illuminate a workspace, a GravityLight SatLight can provide up to 35 Lux. In the same setting, a basic kerosene lamp can only provide about 6 Lux.

+ What is the difference between this Gravitylight and older prototypes?

Our first prototype, GL01, was the first mass-produced iteration of GravityLight. Several thousand were made to test the concept demand and feasibility through trials in off-grid homes across 26 countries.

From the extensive learnings and insights from the trials and 18 months of further development, testing and verification we now have an improved Gravitylight, GL02. The key principles remain - it offers instant power, on demand, without the need for batteries or the sun - but GL02 can now be used by anyone, regardless of height or strength, is more robust and efficient.

Getting Involved

+ Is GravityLight available to buy?

If you would like to purchase a GravityLight please visit our sister organisaiton, Deciwatt, who is responsible for selling GravityLight globally.

A percentage from each sale of GravityLight sold through Deciwatt goes towards supporting the work of The GravityLight Foundation.

+ We’re interested in partnering with you to distribute GravityLight

Great news! We are interested in hearing from organisations already involved in distribution of products to off-grid households in sub-Saharan Africa and Asia.

Please share more about you and your organisation in this form and we will get back to you about future opportunities, once GL02 is launched.

+ I have a GravityLight story to share – where do I send it?

Great! We’d love to hear it. Please do share your stories, photos and videos with us by email, remembering to include your names, location and date. You could also post it on Twitter and Facebook.

+ I want to work at GravityLight – are you recruiting?

Thanks for your interest! Check out the 'We're Hiring' section of our website (under the 'Contact Us' tab). If that page is not there then unfortunately at the moment we are not currently recruiting but, to be kept up to date with any future opportunities, we recommend you follow us on Facebook and Twitter, or sign up to our [newsletter].

+ I have other questions that aren't on here - where do I go?

You can send questions to us by email, Twitter or Facebook.

+ How can I stay updated with your plans, activities and impact?

If you’re on twitter, you can follow us @GravityLight If you’re a facebook person then you can like our page to see our news. Or you can keep you up to date with our newsletter.