question

Hi

what is your ESS Setpoint?

I presume 50W from screenshots, plz try to set it to 150W, then there is a broader gap between the setpoint for the Feedin Setpoint of PV AC Power and ESS Charging Setpoint.

https://www.victronenergy.com/media/pg/6292-ESS_design_and_installation_manual-html5/en/configuration.html#UUID-634c2829-76e8-4e0a-522b-32bbe2cd1c92

Also the Fronius Modbus TCP is quite slow- room for improvement ((esp. with slave invters via SolarNet), so the values for the production are very conservative incase AC Loads drops suddenly.

Hi Ossi,

Thanks a lot for your reply.

Grid setpoint is crrently at 80W.
I tried different seetings between 30W and 200W, but without any effective change in behaviour.

From my point of view the delayed reactivity could be related with my second post on the Feed-In issue, but I don't think, that this is realated to that problem. There is a timely difference up to 45 minutes. In that period there should be a proper communication on Modbus possible.

We have almost the same setup and same suspicion about how the communication works between Victron and Fronius. Could it be the case that Fronius produces equal energy on all the phases , however the zero-feedin misses to regulate properly when the loads are unbalanced ? The question here is, why Fronius is lower its production although the battery is craving for energy ??

somehow the multiplus are reluctant to charge the batteries higher when the loads are quite low.

We are eagerly waiting for an answer to this question.

During year change I performed an additional test, which brought more clarity into that issue. It could help Victron to isolate the route cause and develop a fix for that issue.

1. Island mode (green area in below diagram)
I started the environment disconnected from grid and consumption network.
As expected Fronius inverter and MPPT charged full available power into battery.

2. Grid connected and disconnected Consumption (blue area in below diagram)
In next step I connected grid fuses.
After a short time Fronius power limit got activated, but it was more than surprising that still full capacity was loaded into batteries. The Fronius power limit was corresponding obviously to the total power capacity that Fronius produced at that moment of time.
You can compare in following diagram the green line that represents the parallel MPPT power production to exclude potential sunshine deviations.
This example shows from my perspective that Power throttling does not impact the battery charging process in every condition.

3. Standard Operation ( grid and consumption network connected- red and yellow areas in below diagram)
Shortly after the consumption network was connected and first peak loads appeared, the Fronius inverter got throttled, so that it produced less than 50% of it's current available potential, although battery charging would have been still possible (red part of the diagram).
Unfortunately I have not chosen the optimal time to exemplify that phase for a longer period. In the yellow phase the battery got throttled since it reached nearly full charging level already. But also during that phase (yellow part of the diagram) you can easily reproduce that actual battery charging current was for about 20 minutes still below actual allowed limit!

Conclusion:
As soon as consumption gets in, the AC-Out related power production is not properly redirected anymore via MultiPluses with the consequence

1. not charging the battery with actual available power capacity and
2. not to compensating required power on other phases. Instead power is partially fed into grid (see documented zero-feed-in issue).

For those who want to have a look on the native raw data, I also attached the Excel.

VRM Demo.zip

I can see all of you have done your home work in detail.

I have a single phase system: Fronius Primo 8.2, Multiplus II, Venus GX, Mppt 250/100, Solar MD 7.4kwh battery with BMS, Can bus (can charge at 50A) With Zero-feed in active.

I am having the exact same problem, Fronius goes in throttle mode due to AC loads is not high enough, but battery does not come close to it's maximum allowed charge current. ( And yes all settings are correct, and no i did not miss any thing)

Question 1: Will it make sense to change Venus with Cerbo GX for faster communication to make Fronius to step up and down faster? (Cerbo has faster processor)

Question 2:Is there a possibility that the Multiplus II is to slow to react on Venus GX instructions?

Question 3: Can the ESS Algorithm be changed so that Fronius PV inverter will be more constant (this is the slow part in changing up and down) and that PV MPPT will act faster and that the variable must be more on battery in and out current for variable loads instead of grid (obviously in limits)?

I believe the engineers can look at this at a different angle to increase PV inverters to be more effective.

Not that this is the reason for the situation above, BUT, users should watch out for a correct network connection between the Fronius and the Venus device otherwise throttling will happen, particularly because many are placed in the garage where Wi-Fi is poor, all of my systems have LAN connectivity to both the Venus and the Fronius because I was getting throttling due to poor network connections. Especially when some "DIY network engineers" installed mesh devices in the home which has seen my Fronius-Victron Wi-Fi links come crashing down.