they're saying you might not use the extra energy if your PV runs year round. If you continuously had a year round surplus, you wouldn't have a need to buy any energy, so the credits would be monopoly money.
The grid doesn't give you money in these locations.
They give you credits for future consumption. You can only spend this on energy. If you always have a surplus, you will just rack up large amounts of credits.
In Spain you cannit withdraw it, only spend it with the same provider. If you migrate it, you lose it.
And it makes sense because it's for self-consumption, you are not an energy micro-provider.
