Solar on grid system is a grid tied system where your solar system is installed parallel to your existing electricity grid, hence after going solar you will be having two sources of electricity one is your electricity provider and second is solar. When the sun is shining during the day time you will use electricity from your solar panels to run your appliances and the surplus energy will be fed in the utility grid (export), but when the sun is not shining (at night and during monsoon) you will pull electricity from the utility grid (import) the same way you do before going solar. Hence after installing solar on grid system you will get electricity bill only for the excess units that you are borrowing from the grid (import â export).