Basically the numbers come down to a few things. How much energy does your home use in a day (kw/h). How much energy does your installed solar generate; this is genarally kw of solar times average hours of peak sun for your latitude. So if you want to entirely power your home with solar, and you average 1,000 kw/h a month that's about 33 kw/h a day, and your latitude averages 5 hours of direct sun a day, you need about 7 kw of panels to generate that 33 kw/h.

Then you need to store the excess power to use throughout the rest of the day. If you're off grid, this means a lot of battery. If you're on grid (grid tie) you can generally put your excess power on the grid, then draw it back out throughout the day and your utility company will "net meter" periodically so you only pay for the difference you used, or they pay you for the excess you didn't use.

What utility companies pay for excess residential has evolved and is evolving. A few years ago you could get the full domestic rate (~ $.12 per kw/h) and that is a fantastic rate. Now utilities are pushing for a lower rate to take into account for delivery costs solar does not require [1].

[1] https://insideclimatenews.org/news/11062019/rooftop-solar-ne...