Get an esp 8266, I think you can get a battery add-on for it that takes an 18650.
You'll need to look for a solar charger tho. No, scratch that.
Get a solar power bank and plug it into the ESP. (you may need a boost / buck converter to get the voltage just right).
And of course you need a temperature probe which plugs into the ESP input pin. And you'll need to do a little coding. (example:
https://www.communica.co.za/products/bmt-temperature-probe-ds18b20-1m)
Edit: Not sure about your first question - sounds like you don't know what to ask.