I am installing two sb4000tl-20s on the same phase. Only one array was ready so I put one inverter on-line. No problems. In the week it took to return to site, the single system had generated 99Kwh. When the second inverter went on-line (same phase), both systems looked normal, for a while. Then they started to 'bounce'. When both were on line, it was arbitrary which one would drop out, back-off then come back on-line. I eventually switched the second one off and the first came back on ok. I have applied for a 'grid guard' code but with the grid voltage already at 248V, what would the settings for the two inverters have to be for them to operate together? Any help would be much appreciated.