For any storage system to work effectively, or be “intelligent” as sometimes labelled, you need a smart meter. This device measures the flow of electricity from the grid to your home.
If you consume from the grid, it will tell your storage system to feed in more, trying to reduce or eliminate grid consumption.
If you feed surplus energy into the grid, it will tell your storage system to store that surplus energy. These changes happen in real time in fractions of a second, and maximize the self consumption of your solar energy. Since you don’t feed into the grid you’re also not subject to certification or registration requirements in many countries.