Wiki: Domestic Solar Energy Pros and Cons

Yes, the current reverses direction and so does the magnetic field, meaning the CT output voltage goes negative.

It can only sense the current in the wire it's clamped around though, it doesn't have a 'whole system' view. eg battery outputting on one ring main that's consumed by another would look like export if you put the CT around the tail of the exporting ring main, even though nothing might pass through the meter.

Theo

Ah, that may be a reason. If you need to have G100 then they probably need assurance that you won't export more than the allowed limit, and a random collection of boxes might not meet the G100 requirements.

Feel free.

Theo

Other that at 50 Hz ?

I believe you can tell from the phase shift. A negative current flow in the primary of the CT turns into a 180 degree phase shift of the voltage induced across the secondary.

That does mean you need a reference for mains phase to compare, which the inverter needs anyway.

Theo