The answer depends on the region you're in.
In Brussels, the law specifies that a meter cannot be turned upside down. Self-generation plants therefore require a bidirectional meter, also known as an A+ A- meter, to measure separately the energy taken from the grid and any surplus reinjected. Changing your meter has been free since January 2020.
In Wallonia, your meter must be able to turn backwards. Check this information with your grid operator. In most cases, no modifications are required.
In Flanders, from January 1, 2021, the meter will no longer run backwards. It will therefore be necessary to change the meter when you install panels.
