The solar PV panels on the roof absorb light and convert it into electricity. A device called an inverter, conditions the electricity so that it is suitable to use in the house.
When you use more electricity than the solar panels produce, the solar energy is topped up with electricity from your supplier. If the panels are producing more than you need, the excess is exported to the grid for others to use.
Every unit of electricity you use from these panels is a unit you don’t have to buy from your electricity supplier: saving you money.
And if you can time the use of appliances, such as dishwashers and washing machines, to the middle of the day when the panels are producing at their peak, you’ll save even more.