When installing solar panels, they are connected to the public electricity network through a two-way meter, meaning that you can calculate the value of your consumption from the public network and at the same time calculate the value of solar panels production in a separate way. You pay the electricity company the value of your consumption and the electricity company pays you the value of the production. Which means that if the value of production is higher than consumption, this is in your favor because you will get a profit from the electricity company. If the value of production is less than the value of consumption, it is also in your favor because you will pay less consumption value (smaller segment). If the two values are equal, you are also a beneficiary, because in this case you will not pay anything.
