You should be glad that it’s only the federal states with different requirements. Here in Germany, we still have 800 distribution network operators, all of whom set their own rules (defensive measures).
Hi, I’d also be interested in your solution for the AC-coupled Hoymiles microinverters.
As a precaution, I installed a Hoymiles DTU Pro in my system so that I can control the microinverters. However, my installation does not (yet) fall under the controllability requirements.
In principle, this would probably also work via contact inputs, but I’d prefer control via the Cerbo and Modbus so that I can maximise self-consumption.
Searching for “Hoymiles Modbus Implementation Technical Note” for an overview of the registers might also be helpful, as I couldn’t find out everything the device is capable of from the DTU Pro manual alone.
Hello!
Microinverters:
In my case, commissioning was completed before the 1 June 2025 cut-off date (Netz OÖ). That means I only had to carry out the preparations for zero export, and therefore I don’t have a ripple-control receiver/LSG either.
Unfortunately, I can’t provide any more details about the remote-control functions of the Hoymiles DTU Pro.
I installed an OpenDTU. In the OpenDTU browser interface, you can configure various parameters, including a power setpoint. Whether the OpenDTU can also be controlled remotely would need to be checked.
To log the power/energy data from the microinverters in the VRM, I integrated an Energy Meter VM-3P75CT.
Addendum: My implementation of zero export for the Multi (Master)
To simulate zero export for the commissioning/acceptance of the PV system by the grid operator, I implemented it as follows:
Control: Phase from NZHS → LSS B10 → coil of the 230 V coupling relay (Finder) → neutral conductor
Signal path: Normally-open contact of the coupling relay → RJ45 socket (DIN-rail mounting) → network cable plug (at least AWG23) → AUX1 of the MultiPlus
Function/simulation: When the LSS is switched on, the relay energises and the two contacts on AUX1 are closed → zero export
Hello,
a simple on–off switch would have served the same purpose, and you could also have wired AUX1 directly through the contacts of the ripple control receiver.
you could also simply have used the fuse as an on–off switch.
cheers
Hello,
it would of course have been easier to implement, but the requirement was to prepare it as defined in the implementation specifications.
Since no ripple control receiver is installed, using interposing relays is a neat solution and also makes it easy to add additional contacts later if necessary.
Hello,
In Styria, zero feed-in is sufficient when the contact is switched.
However, since I also have a Fronius on the AC OUT and another on the AC IN in addition to the MPPT RS 450/200 (configured to switch off via AUX1) (because of the cable runs being too long), I would like to regulate everything down to zero when the contact is switched by the e-networks.
It would theoretically be possible to duplicate the contact signal (there is a spare Cat cable to each inverter), but a digital solution via Node-RED would be preferable for me.
Unfortunately, I have no experience with Node-RED at all, so I wanted to ask the community: does anyone have instructions for a solution, or perhaps even a ready-made template?
Wouldn’t it be enough to reduce the maximum feed-in to 0 W via Node-RED? That way, the Ekrano would regulate the Fronius units and the MPPT down to self-consumption, wouldn’t it? Or am I misunderstanding this?
Right, I need to bring this topic back up again.
This applies to WLV NetzNö, Victron and Fronius Symo.
Priority 1: I/O control
Priority 2: Modbus
In the utility company editor, set just one rule for 0% for Fronius, and none for 100%.
AUX1 contact on the MultiPlus and the contact on the Fronius for the 0% control.
If the contact on the Fronius is not closed, Modbus controls it because there is no 100% rule.
Is that correct now?
Kind regards
Tested?
The first line in the input control may be unnecessary, but it certainly can’t do any harm. This also means that the state is clearly defined: no signal means 100%. The only dilemma I still have is the country-code setting. I have set it to AT1E as specified, but this causes problems in island mode, because MG50 is apparently the correct setting for frequency shifting … unfortunately, I don’t know that for certain and haven’t yet figured it out.
So I’m considering using the Cerbo’s generator control after all, to switch off the Fronius when the SOC exceeds 80%. It isn’t really wired up yet, but it works perfectly in test mode: the relay switches off at 80% and back on at 78%. And, strictly speaking, every inverter is a generator …
“Frequency shifting” is actually also defined in the country code. I don’t know how it works in Austria, but the German grid code specifies curtailment up to 51.6 Hz; at 51.7 Hz, the system is shut down. You don’t necessarily need MG50.
Yes, but will Modbus still work then?
No, not if you configure a condition for 100% in the Fronius. For the Fronius to switch to the next priority, no condition may be met. To regain Modbus control when the EVU setpoint is 100%, only the conditions for 0, 30 and 60 should be configured in the Fronius I/O. An “unknown” switching combination forces the Fronius into priority 2. Priority 3 would be to reduce the output to 0% if Modbus fails.
But honestly, Modbus control is completely unnecessary anyway. Why would you ever need to “manually” curtail the output?
Export limitation with Victron?
Why? What did you enter there?
What do you mean, what for? If NetzNÖ says I’m only allowed to feed 4 kVA into the grid, then I enter this value in the ESS.
Oh gosh, sorry. I hadn’t thought about all the previous posts. That makes sense then 
.
Somehow, I have to agree with you there. But my “tests” show something different. The system was running in test mode with exactly this configuration for some time. However, the maximum feed-in was set to 0.
And it worked flawlessly … hmm … the Cerbo throttled down both the Victrons and the Fronius … although I noticed that the Victrons are throttled down first. When there is enough solar energy available for self-consumption, the MPPTs are throttled down first, and as soon as the batteries are full, the Fronius is adjusted to the current demand; the MPPTs then deliver exactly 0 W. At first, I didn’t understand this, but regarding direct self-consumption (230 V), it seems logical. Ultimately, a standard inverter such as the Fronius has a higher efficiency because it doesn’t run via the 48 V bus.
Where do you enter this value? I entered it under Grid feed-in, in Maximum feed-in (currently 0). At the time we took the screenshot for EVN (during the trial operation), it was set to 4000 W.
As soon as I have approval to operate connected to the grid, I’ll post the complete documentation for my system here, including all the settings.
This is getting a bit complicated now… If Priority 1 in the Fronius exceeds 4 kW at 60%, the Fronius is not throttled by the Cerbo.
The wording under “Grid feed-in/AC surplus feed-in” is an unfortunate choice by Victron. For the Modbus control to take effect, AC-coupled… surplus feed-in must be disabled. Then the message at the bottom says “Feed-in limitation active”, yes.