You use electricity from your solar panel at day time and use your electric company again. So you will have solar system loan payment and smaller electric company bill.

You can check your electricity bill for daily usages to decide how many solar panels that you need.

You use electricity from your solar panel at day time and use your backup battery for night time. If you have enough battery size for daily usages, you will have $0 for your electric company bill.

You can check your electricity bill for daily useages to decide how many solar panels and batteries you need.