Vladimir

I can confirm that the capacitors solved my problem. Prior to this mod, the output voltage in my parralel setup was fluctuating so much that the setup was useless (flickering bulbs, turning on UPS etc...), now everything works fairly stable. But I recommend foil capacitors (grid ones, motor capacitors etc..) I used initially 400V electrolytic capacitors but after few days they heated up and vented (terible smell). Now using foil capacitors - they are bigger, but do not heat at all and have much lower ESR. You need at least 5uF, the more, the better - but be carefull when they are charged.

Today I received a document from the company in China that sold me the invertors addressing errors 72, 08 and 60. They suggested to put 18uF/600VDC across PV terminals. I can't however find capacitor with that kind of a specs so not sure if it isn't bs.
sop of capacitor(31-013935-00g) assemble to pv terminal ( f72&f08&f60 and flicker issue).docx