– LightInk is a visible, DIY solar-powered smartwatch that differs from commercial models by exposing the solar panel and requiring user assembly and custom components.
– It aims for long battery life (up to ~10 months on a 100mAh cell) but sacrifices some features (no accelerometer) to save power.
– Key tech: E Ink display readable in sunlight with backlight, LoRa support, GPS, speaker, and no companion app yet, placing it between a wristwatch and a smartwatch.
Introductory glance at solar-powered wearables
Solar-powered smartwatches are still niche products in the overall market, though that does not mean such watches do not exist. The best-known models are probably Garmin Fenix smartwatches such as the Garmin Fenix 8 that we reviewed back when it launched. On these smartwatches, the solar panel is more or less invisibly integrated into the display.
What makes LightInk stand out
The so-called LightInk takes a different approach. On this smartwatch, the solar panel is clearly visible and separated from the display. There is another major difference, as the LightInk is not a commercially available product but comes from the DIY scene and therefore cannot simply be bought. Instead, interested users have to assemble the watch themselves. A detailed guide is available. In most cases, users have to have a circuit board manufactured by a service provider, own or have paid access to a 3D printer, and be able to do some soldering.
Performance and design tradeoffs
The LightInk is designed to offer several months of battery life. More specifically, up to 10 months should be possible with the 100mAh battery. There is no accelerometer because it would simply consume too much power. However, LoRa is supported, it uses an E Ink display that remains readable in sunlight and also has a backlight for use in the dark, and there is a speaker as well. GPS is available, but there is no companion app yet, which means the LightInk sits somewhere on the boundary between a regular wristwatch and a smartwatch, at least in this respect.










