Having a solar panel instead of having electricity from an electricity company will cost you a lot. I don't wanna stress this that much but it will really cost you tons of money. Knowing that your "small farm" will be having mining rigs that should be able to generate 3-4K USD a month (in profits, other stuffs aren't counted yet in this price), then that means that you're gonna be needing an electricity that is sufficient to power these rigs every day and every night. With the additional electricity consumption for the ventilation of the mining rigs.

The mining rigs alone will cost you a lot, the land and the materials that will be used in building the room for the farm will cost you a lot, the solar panels will cost you a lot = This is some serious large amount of money.