The project is to have a remote station–either low power sensing or camera enabled that periodically communicates with a base station. The remote station would be powered by a solar panel, and store power either in a lithium-ion battery or in a super-capacitor. The battery solution would be higher power. A supercap solution would be very low power, storing energy and then periodically waking up to take a reading and send the data to the base station. The supercap solution could potentially last for decades, while a battery solution would need a new battery after a year or so, and would have poor performance in the cold.
1) Solar powered camera. Solar panel, supercap, Raspberry Pi Zero, camera, and wifi. Wakes up periodically, if there is sufficient charge, takes a picture, connects to wifi, sends the picture.
2) Garage temperature monitor. This one could run off battery alone.
The hardest part of this project is figuring out the power requirements, and how to charge the supercap or battery. The Raspberry Pi draws a lot of current when it starts up, and wifi requires a lot of power.
Low power projects done by others:
Linux Throwie: Powering a Linux Server with a 0.3W Solar Panel
ESP32-CAM WiFi + bluetooth Camera Module Development Board ESP32 With Camera Module OV2640, $9