I have a DC-INT (DC interference) fault

[andrevans]

I have a recurring DC Interference fault on my solar system. I have gone through all the scenarios recommended by Solis, but still no solution. All I can pinpoint is that the fault occurs when the batteries have just equalised at 100% and there is an additional power demand such as switching on a kettle or washing machine. Any advice as to what I can look for? The inverter was swapped out by Solis last year but still no result. MY system is as follows:
17 JA solar 535W panels in 2 strings
Solis S5 EH1P-6K Inverter
2x Hubble AM-2 batteries (5.5Kwh each)