I think this option is very good and it will be less expensive
I disagree, even with government subsidies solar panels are still incredibly expensive. It'd take a very long time to get a return on your investment.
That is correct. This is one reason why solar electricity is not so common (in general and not specific to mining).
It is abundantly available and if it indeed were inexpensive, you would solar electricity easily overtaking coal/other non-renewable sources of electricity.