[RE-wrenches] XW grid connect question

[Jay]

Hi all

I've got a friend of a friend who is having trouble with his XW 5548 selling to the grid

It appears that it'll sell up to around 2.2k, and that's it. There is 4 kw hydro going into a XW high voltage controller. 
Yes it has all correct dump and safety components so nothing is blowing up. My friend has 3 other exact same systems all,working fine. 
Setpoints are all set correctly and have been double triple checked and are the same as the others. 

I guess my question is if the grid voltage was high enough that the inverter was bumping up against max AC voltage, will the inverter regulate watts to stay at that voltage or shut off like a normal GT inverter?  

Or could there be another reason/s?

Thanks

Jay
Peltz power.