Proposal for ESS manual update, explicit Fronius GFDPR and anti-flicker settings

Been running a Victron ESS setup with a Fronius Symo on AC Out for about 18 months now and this is something that's genuinely been bugging me. The documentation gap between what Victron's ESS manual describes and what you're actually navigating inside the Fronius Profi Menu is significant — especially for anyone who hasn't done this before.

Specifically:

• GFDPR (Grid Frequency Dependent Power Reduction) settings in the Fronius menu don't have a clear 1:1 explanation in the Victron docs
• Anti-flicker / power smoothing — took me ages to work out which Fronius parameters actually correspond to what Victron ESS expects
• The interaction between frequency shifting (Victron's method of curtailing the Fronius) and those Profi Menu values isn't documented anywhere obvious

I ended up piecing it together from old forum threads, a YouTube video from an Australian installer, and a lot of trial and error. Shouldn't be that hard in 2024.

A proper addendum to the ESS manual — even just a table showing "Victron ESS field → Fronius Profi Menu equivalent" — would save a lot of head-scratching, particularly for UK installers dealing with G98/G99 compliance questions on top of everything else.

Anyone else had to fumble through this? Would be good to know if others have found reliable settings that work well, or whether there's a consensus forming around particular GFDPR values for UK grid conditions.

Feels like this is exactly the kind of thing the community could put together collaboratively if Victron aren't going to update the official docs anytime soon.

My Fronius spent its first three months doing interpretive dance with the grid frequency until I stumbled across the GFDPR setting buried in a Reddit thread rather than, y'know, the actual Victron manual.

@MariaJones that "interpretive dance" description is painfully accurate — I had exactly the same thing on my Symo 8.3 before I dug into the Fronius Service menu properly.

The bit the ESS manual completely glosses over is the GFDPR curve steepness interaction with Victron's frequency-shift power reduction. If your Fronius is configured for EN 50549 defaults and your Multi's frequency shifting is aggressive, you end up with both systems essentially fighting over the response curve simultaneously.

Specifically worth documenting:

• fstart and fstop values in Fronius need aligning with Victron's ESS frequency droop settings
• Anti-islanding sensitivity on the Symo can misread Victron's intentional frequency deviation as a genuine grid event

I had to log about two weeks of CCGX data before the pattern became obvious. Would strongly support a dedicated appendix in the ESS manual covering Fronius-specific commissioning steps rather than burying it in community wikis.

@Chalky12 completely agree this documentation gap is a real problem. On my static caravan setup with a Quattro 10kVA and Symo 5.0, it took me the better part of a fortnight cross-referencing the Fronius Solar.web interface against VRM logs before I realised the GFDPR threshold needed explicit alignment with the ESS grid code settings — neither manual references the other.

What made it worse was that Victron's ESS assistant has its own frequency shift parameters that can actively conflict with Fronius's defaults if you're on a non-standard grid profile.

Would strongly support a dedicated section in the ESS manual covering:

• GFDPR sensitivity alignment between the two systems
• Anti-islanding coordination specifics for AC-coupled Fronius units
• Anti-flicker (Pst/Plt) thresholds relevant to UK G98/G99 compliance

Has anyone actually raised this formally via Victron's GitHub documentation repository? That seems the most direct route.

@Chalky12 solid proposal. Worth noting the GFDPR interaction becomes particularly spiky if you're also running the anti-islanding settings at their defaults — the Fronius will see the MultiPlus/Quattro's frequency shifting as a grid anomaly and trip unnecessarily.

On my narrowboat setup I've got a Multi 2 rather than a Fronius on AC Out, but I spent enough time in the Victron Community forums untangling this for others to know it's a genuine documentation black hole. The ESS manual references GFDPR settings in passing but never explicitly walks through the Fronius Primo/Symo configuration screens where you actually set them.

A dedicated table cross-referencing:

• Victron ESS assistant parameters
• Corresponding Fronius GFDPR values
• Anti-flicker thresholds

...would prevent a lot of unnecessary callouts. Suggest raising it directly on Victron Community as a formal documentation request — they do occasionally act on those.