How can I see my AC coupled PV?

DIY
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Continuing the discussion from Multiplus ii and Pylontech system using the grid as well as solar excess to charge batteries:

Hi @nickdb

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My system is running the ESS assistant. As well as some MPPT PV I have about 8kWp shared across 4 AC coupled arrays in parallel with the MP2 ACin for a couple of years and all seems to be working as expected. I have been unaware of the requirements you quote above.

Being grid-tied, I’m not sure why there would be a requirement for the AC coupled inverters to be controlled by Victron. They die when the grid is disconnected.

I do have a c.t. Measuring the combined output of the AC coupled solar. This is being recorded in emonCMS using an OpenEnergyMonitor emonPi.

Do you know of any documentation how I can route those c.t. readings into the Cerbo so that I can more closely match the ESS requirements and get better “export to grid kWh” readings in VRM.

Thanks, David.

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On the AC input this isn’t really an issue, hence why factor 1 rule doesn’t apply. There are some other issues that arise with PV on the input side such as fringe cases where DC PV will throttle back to zero. On the referenced case there is next to no information available and it is completely unclear where PV actually is - it doesn’t appear to be a conventional config.

You want to know what a PV inverter is producing so it is reported correctly, grid meters etc required so the system can do this and compensate for parallel load if they exist.

From an integration perspective, node red really is the answer for inverters that lack a native integration. You can create a virtual PV inverter and feed it the relevant data from wherever you can get it. This will appear and report like any other PV inverter in VRM.

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Thanks for the reply Nick.

I’m keen to keep my ESS-enabled system working smoothly with its ACin coupled PV, but without some step-by-step worked example to follow, I will find the nodeRED, MQTT route rather too challenging to achieve

Is there any documentation for what you say is a pre-requisite for ESS? I want to avoid the unexpected problems you point to.

I’m still bothered by the assertion that in order for ESS to work the PV must be under Victron control, eg by frequency-shifting. I thought ESS was not applicable in off-grid settings and frequency control is not applicable in on-grid

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It’s relevant where the PV is on ac out, not IN.

Following the installation reference material and training does show how both approaches needs to be done.

We weren’t discussing off-grid usage where ess shouldn’t be used, but also why there is a dedicated PV inverter assistant.