The transformer only supplies my house, however it was undersized for when the farm was a working farm with high power demand for milking coolers etc. Therefore it was 'tapped up' to give 253 volts to maximise power output. This makes it sensitive to high input voltages, causing the windyboy inverter to trip out, unless there is a high load in the house.
I will report developments. The next step is to get the export meter fitted and sign up to sell the excess and ROCs.