Micro inverters on same install
I have just put in a 12kw 3 phase inverter with about 10kwh of batteries into my residential system. This already has 24 panels with enphase inverters mounted on the roof feeding into the main distribution panel. These, when there is excess, are powering a 3 phase immersion heater under the control of a raspberry pi (along with a bunch of automation features).
The question is that the inverter is not measuring the power usage correctly and I suspect its just the existing feed from the Enphases is coming into the wrong spot. For example, the panels are generating 6.5kw at the moment of which 6kw is being used as load (primarily that heater) with 0.5kw off to the grid. However the inverter is showing 6kw in from the grid and 6kw off to load. The inverters CT's are on the grid feed in (before the enphase feed in). the inverter has the entire house load being fed through it (but after the enphase connection).
Final sum up here if anyone finds it useful in the future following a couple of weeks of tweaking. Connected my Enphase system to the SunSynk (12kw 3 phase) AUX input port and configured it for Microinverters (3 phase - 24 Enphase IQ7+, IQ& Relay, Envoy controller). It seems to work well dumping any excess power off to the grid once local loads are consuming (cars, heaters etc). Accidentally drained my batteries (2* Dyness 5.0c) a couple of times when the local load did not automatically switch off when the power dropped.
Game changer for me was moving off the SunSynkAPI (nominal 60 s updates although often seems to be minutes) for monitoring and on to RS485. Suddenly changes were in real time and I can program in all the load control conditions properly and diagnose problems by testing conditions.
Also came to realisation that trying to squeeze every last watt out of the solar power is not good for the blood pressure and need to take a more relaxed approach.