OK, Pieter, I've bought a 10w solar panel, a MooHoo solar controller - it has both 5v and 12v simultaneous outputs, so I believe I have separate power that way to each device (solenoid and ESP8266). I also bought a Huzzah Feather instead of just the 8266 module I have. Looks like programming will be simpler and since power can be supplied through the USB (which is how the solar controller outputs 5v), seems like the power on that side is covered.
So, I'm seeing it as huzzah, breadboard, the MOSFET's, the solenoid. My one question (till the parts are all in hand) is do I wire the 12v output from the controller where ground goes to the breadboard and positive to the solenoid? Nothing needed between those parts?
I think I've got or can find, the setup on the board once I understand this. I'm not just asking for solutions without doing a LOT of research, but finding an answer that's both simple enough for me to understand and specific enough to my situation to feel good about it I've not found.
Thanks again for any suggestions.