It’s highly recommended that off-grid solar powered systems have a back-up source of power.  This is because especially in winter when you can get a number of days of rain in a row, you’ll likely want to continue to run your appliances as you normally would.  If you’re in a situation where you’re already on the grid and want to go off-grid, instead of getting a generator, there’s an option of installing a switch which would enable you to switch off-the grid during the summer months & just pay the line fees, and then switch on and off the grid as needs be during the winter months.