I am making my mother an automated watering system for her garden with my Raspberry Pi. I would like the system to be able to detect soil moisture, as well as predict temperature and humidity to determine when it is best to water.
There are several different locations in our yard where I could deploy the Pi, most of which present a challenge as far as powering the device. If I am going to have the Pi do the watering itself (instead of just notifying me when it's time to water), it needs to be connected to a relay which triggers a solenoid valve that allows water to flow for a certain amount of time.
If I want to run such a system in a part of my yard which is difficult to power (expect by running an extension cord the length of my lawn), are there feasible and relatively inexpensive solar panel solutions that would power a Pi Zero W performing such an application indefinitely? From my testing, there is a decent 2.4GHz wifi signal in all of the garden locations that I would like watered, so internet connection is not a problem.
Regardless of if solar power is feasible (I could limit my efforts to the locations for which wired power is doable), does using a relay to send power to a solenoid valve sound like the best way to do the actual watering?
Note: I currently have a Pi 4B which could be used as a central controller device, and I was imagining several Pi Zero W's, one for each area I would like to be watered.