Solar Protocol is a web platform hosted across a network of solar-powered servers set up in different locations around the world. A solar-powered server is a computer that is powered by a solar panel and a small battery. Each server can only offer intermittent connectivity that is dependent on available sunshine, the length of day and local weather conditions. When connected as a network, the servers coordinate to serve a website from whichever of them is enjoying the most sunshine at the time.

Via Solarpunks.

Solarpunks were prescient when they asked (in 2012):

What would computing look like if it had to get its power from purely local and renewable sources? What is the potential of low-and-no-power computing and sensor networks?