Hi everyone,
I’m hoping someone can shed some light on an issue I’m encountering. It appears that the ESS Peak Shaving setting is directly controlling the AC Input Current Limit of the MultiPlus. This means that the Multi is limiting total current at the AC input — and since our solar is AC-coupled before the Multi (on the AC-IN side), the system is combining both grid and solar into this limit. As a result, solar production is being unnecessarily injected, when this could be used to charge the battery.
As in Belgium we are paying a fee based on our peak consumption, is there a way to make Peak Shaving use the grid meter measurement instead of applying a blanket AC input limit? Allowing me to limit the grid use to the defined peak shaving value. But allow solar production to flow to the battery even when this is higher than the Peak Shaving value.
(Essentially I think the AC Input Current Limit should be Peak Shaving + Solar Production)
System Details:
- ESS Mode: Optimized without BatteryLife
- Battery: 280Ah LiFePO4
- DVCC: Enabled
- BMS Parameters:
- CVL: 55.2V
- CCL: 95A
- DCL: 143A
- Inverter (MP2): Configured with a charge current limit of 70A in the VE.Configure settings, but checkmark enabled to allow overwrite.
- ESS Peak Shaving: Set to 13A
Observations:
- If solar alone is producing more than ~3 kW, the Multi is not using this for battery charging or the AC loads, as this would be over the “AC Input Current Limit”
- The system regularly exports to the grid, and I’ve seen grid injection as high as 2000W when solar production is close to 5000W.
- Switching to Keep Batteries Charged bypasses this, as expected, and allows charging up to the full 70A
I can resolve this by raising the Peak Shaving to 20A as this would allow close to all solar to be allowed. However, when my SOC-min is reached i would only be shaving anything above this 20A and not the 13A I would like.
Attachments:
- Screenshot 1: Dashboard showing 2900W (13A) being used and the rest of the solar being exporting
Any help would be greatly appreciated!
I’ve made a quick schema of our installation.
Note that the SmartSolar is currenly not yet installed. Still need to find the time for this.
My AC-Coupled PV is connected to AC OUT.
I was from the assumption that this is only allowed if:
-
The max PV power must be equal or less than the VA rating of the inverter/charger. (Ref: 2. The Factor 1.0 rule)
In my case the multi is 5000VA (4000W) where my PV inverter is 5000VA (4999W)
So depending on what power figure we are referencing. This might just work or is to high.
-
The PV inverter has “frequency shifting” to regulate that power and prevent overcharging the batteries. (Ref.: 1.2 What is frequency shifting? )
My inverter is not compatible (as far is I know) with any form of frequency shifting.
Meaning that in case of a grid failure this might cause issues when the battery is full. As there is no place for the energy to go.
Or am I missing something here?
What might be a solution would be to move the solar to the AC-OUT2. In that case the PV Power does not count to the AC Input Current Limit. And when there is a grid failure this output is disconnected, so no risk for overcharging the batteries.
You are correct.
I think we have the same MultiPlus. 48|5000|70
I have a Sunnybox 3KW with frequency shifting and a MPPT RS 450|100. Maybe a different story.
I live in Begium as well and never use more than 2.500W from the grid. Programmed it with Node-Red.
You’re right — this does seem very similar.
I discovered that the Sununo does support AFD (Active Frequency Drift), but I haven’t been able to find any settings to configure the frequency range to what it responds.
The only related setting I found is the grid compliance profile, which is currently set to C10/11 — the standard for Belgium. From what I understand, Synergrid defines the AFD requirements in this case. However, I’m still unsure which frequency thresholds I should configure in the Victron ESS to ensure proper coordination.
I’ve seen conflicting information: one source mentioned that C10/11 is quite strict and enforces a full shutdown at 50.2 Hz, while another stated that the standard actually allows a ramp-down from 50.2 Hz up to 51.5 Hz.
How did you set your frequency shift in ESS?
These are my ESS setting.
Thanks, Diederik, for sharing your ESS settings!
I had a look, and they do seem to match Victron’s default frequency shift values. To double-check compliance, I referred to the latest version of the Synergrid C10/11 technical prescription (dated 17/10/2024 – Technical_prescription_C10-11_ed2-3_20241017_tekst_NL.pdf).
According to this document, the valid frequency domain is 47.5 Hz < f < 51.5 Hz. For the power response to overfrequency, it points to the relevant requirements of EN 50549-1 or EN 50549-2 (2019 edition, §4.6.1 ‘Power response to overfrequency’), including some local adaptations.
§4.6.1 specifies that the energy-generating unit must gradually reduce its active power output as the grid frequency increases, starting from 50.2 Hz. This reduction should follow a linear curve—typically 40% per Hz—until output reaches 0% at 51.5 Hz. This behaviour supports grid stability and is a key requirement for regulatory compliance under Belgian C10/11.
Out of curiosity—has your installation already been inspected and approved with these settings?
And do you recall where you found the settings you’re using—Victron documentation or another source?
Really appreciate your help—I’m doing my best to ensure my setup is fully compliant.
I haven’t done the first setup myself. All was inspected and approved.
After the installation I programmed the unit with Node-Red myself.
I’m planning to clone your settings because I believe the 50.2–52.7–53 curve accurately represents the PV powershift. Victron will indeed be able to shift over the full range, but our PV system won’t support the entire range and will shut down prematurely since C10/11 forces a shutdown at 51.5 Hz.
To correctly determine the appropriate frequency response, the entire curve needs to be configured.
If I were to set my minimum frequency point at 51.5 Hz, it would steepen the curve significantly and lead to inaccurate lookup points.
Hello.
Interesting thread 
I’m also in Belgium, with capacity fees …
My system is made of :
- 3 x MP2 5000/70 (I have a 3x400Vac net connection)
- 3 x SunEzy_2000 1-phase PV inverters 230V/2000W ac, without any power modulation (too old …)
- 280Ah 16S LFP battery with JK BMS
I had to set my PV inverters on AC-Input 1 side, because they do not respond frequency shifting, they just shutdown above a given value (too old units).
Now, from all your messages above, I think you are forgetting one important point …
The throtelling of your PV inverters by the Multiplus via frequency regulation will ONLY be used in one specific case : when the grid is OFF and your Multiplus are working in island mode, because that is the only moment where the multiplus are able to “play” with the frequency.
When the grid is present, the multiplus must follow the grid frequency on both input and output … that is why the throtelling of the PV inverters is always done via Modbus when the system is on grid.
Frequency shifting is more a “last safety measure”, but modbus should be the main communication channel.
