Poor power factor value through energy meter on maximum solar power exported to grid
I'd always assumed that "bi-directional" and "net metering" were the same thing, so I can't make sense of that bit.

Could you post some of the measured accumulated kWh and accumulated kVAh numbers with time periods for both the "normal" and "bad power factor" time periods please?

However, what I suspect is happening is one of two things:

1) the power company's power factor measuring system is single-directional and treats reverse flow as a 180 degree out-of-phase power factor, calling it "bad".

2) the meter is single-directional and only calculated power factor when the panels were not exporting. Since electricity consumption was down to a few items, the power factor was much worse - but calculated over a much smaller amount of electricity.