this can be disallowed in the UK, depending on their agreement either their provider. the OP is exporting way more energy than they have ever produced through solar; in effect they’re selling back off-peak energy to the grid, which is making a profit
Why would it be disallowed? That's a useful service to the grid – it's renting energy storage.
UK off-peak energy is mostly surplus of wind, while the peak is burning natural gas. Feeding off-peak energy back to the grid at peak times makes it greener.
