3 phase PV system import/export

I have 3 phase PV system and utility meter monitor each phase separately for export and consumption. I found PVoutput can’t calculate import/export like my grid, so I did 3 PVoutput systems for monitoring each phase and they work correctly. But Data Aggregation for parent system is wrong form my situation. Data Aggregation is done like all systems are on same phase and result is same as I had 1 system before splitting. How to solve this problem? I want import/export statistic similar i have billed.

The aggregation would add all the individual systems monitoring each phase into the parent system. The import / export is the calculated excess between consumption and generation.

How does the utility calculate this? Best to show the differences between PVOutput and the result you are expecting.