One solution might be a local voltage reducer in the building ( a low voltage high current winding to oppose, or buck, the incoming supply, auto-transformer style) so the 250V DNO side is then transformed down to more like 230-235 V in the building, better for the inverters, and better for things like the life of light fittings too.
Harry Macdonald:
"get them to tweak a control knob to bring the Voltage down".
Don't follow. I thought the voltage rises to the level needed to export the power being generated.. No control knobs to tweak.
Regarding loads, you forgot the beer coolers!
The maximum and minimum Voltage levels must be set and controlled, so reset them. That is what I meant.
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