I had an electrician round at the weekend to investigate and was massively glad I did. When he opened the fuse box to check the wiring he found this!
|Solar Panels Tripping Out Inverter|
It appears that the wires weren't fully tightened so we arcing and ended up melting the live and neutral wires together. Fortunately it's happened in winter, in summer with 3kW feeding through it may have been a far worse outcome and ended without the house.
Fortunately the solar panels are now working fine and have been stable with no trip out since the work was done.