Off-grid solar electricity is for homes that do not have access to grid electricity -i.e the house cannot be or chooses not to be supplied electricity from a power company. These systems offer complete autonomy and independence from the national grid and power companies, meaning you never have an electricity bill.
Simply sun shines on solar PV panels on your roof or mounted near your house. These panels generate electricity which is used to power your home and charge your batteries. The batteries allow you to store electricity for use at night or times of low production like cloudy days.