[IshKebab]

But unless you're off-grid you can always use extra PV energy by selling it to the grid.

[knollimar]

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.

[IshKebab]

What locations? In the UK they give you actual money. You can withdraw it.