Wristwatches come in many shapes, sizes, and types, but most still have at least one thing in common: they feature a battery that needs to be swapped or recharged somewhere been every other day and every few years. A rare few integrate a solar panel that keeps the internal battery at least somewhat topped up, as environmental light permits.
This is a companion discussion topic for the original entry at https://hackaday.com/2024/03/13/a-solar-powered-wristwatch-with-an-attiny13/