Fronius Primo Gen24 wake up from standby

Hi there,

Firstly a big thanks to those on this forum particularly in the below threads who have been of enormous help getting my solar & battery system integrated via Modbus for statistics, control & automation.

I have an automation that runs a force charge on the battery at 2am to take advantage of the lower power prices at this time. It is winter in Australia so the battery is discharging during the evening and is typically discharged at around 9/10pm.

When I first set it up it was working OK but the last few weeks has been randomly failing. On checking the status logbook it appears that the inverter is going into standby/sleep mode when the battery discharges to its limit and then is bouncing around a few states when the automation triggers at 2am changing the registers required to start a force charge. Some days it charges, some days it fails to even start. Some samples below :

This one didn’t even start

|sensor.master_inverter_operating_state|OFF|2024-06-13T16:01:03.614Z|||Automation triggered at 2024-06-13T16:00:00Z|

This one finally got going but a good 15 minutes after the trigger :

|sensor.master_inverter_operating_state|OFF|2024-06-14T16:01:24.598Z|||Automation triggered at 2024-06-14T16:00:00Z|

I have a feeling that it might be something to do with the standby/sleep approach in that it wakes up on getting the register changes but then seeing the battery charge is still below the threshold it wants to go back to sleep again.
My preference is to stop it from going to standby/sleep altogether but I cannot find a setting on the inverter or a register to do that.

Thanks in advance.

What could work is to set the reserved battery capacity higher with modbus.

Hi John, Thanks for the response.

Yeah I have thought of that, I will try it. From what I can see there are 3 settings that impact there, given I have a battery backup setup on the Fronius in case of a grid power outage.

The two on the WebGUI, there is one one under Functions and I/Os for Backup Power.

For a day to day discharge, this 7% limit is where the system currently stops any discharge.

The 5% is set from the manufacturer but is overrulled by the previous 7% setting.

Then there is the Modbus register MinRsvPct which is what you are suggesting I change which might do the trick.
That said this is what happened last night. Despite the battery charge state never getting anywhere near the limits it still went to sleep at around 1.25am despite it discharging and providing power to the house up until that point. It wakes back up again at 1.44am. Is there a minimum discharge current for a period of time that is triggering and sending it to sleep or something like that??

Normally when this happens there should be a message in the WebGUI why he went off. I don’t think that it has a minimum output, but I am not an expert and our Symo supplies about 200W continuous throughout our night. You can check the load sensor to check that. Also there could be external factors like over- or under voltage from the grid or if you have that a signal from your energy provider.
The MinRsvPct could be the one but isn’t that for backup reserved percentage? I am not sure bc I don’t have the registers at hand now. We have electricians here at the moment and no power.
You can also try the one for the normal battery percentage.

Thanks again John,
So I tried changing the WebGUI backup to 6% and then the register MinRsvPct to 7%. It stopped at 7% during the evening but again failed to wake up on the automation trigger at 2am. It eventually started charging at 3.45 but cut out at 4.45 and started again just before 5.30. Whole thing seems completely random??

And just to round it out it worked perfectly as expected this morning!!

What I initially meant is to let it charge and maybe wake up by setting the minimun percent to something like 50. Then it will for sure wake up and charge. At least thats how it works with mine.

Hi again John,

I’ve tried setting the MinRsvPct to something higher and that is not having any effect. I think that register overrides anything on the webgui as the new min SoC which then triggers inverter to sleep if there is no solar. I did check the webgui error logs and there is something coming up there :

GEN24-1118 Permissible reconnection voltage of the inverter exceeded

That error is showing in sync with the inverters trying to wake itself up. If anyone has any understanding on what this is that would be great.

I think that it means that either the battery or grid voltage is too high.
You should ask your installer or fronius directly what you should do.
But can you send any images of your voltage sensors here first? Like the voltages of the phases from your smart meter or the dc voltage of your battery.

Hi again John,
Thanks for the responses, you have been of tremendous help, and I think have nailed it there.
I’m angry with myself for not thinking of the obvious, I just assumed the line voltage could never be a problem but it is going a long way above 240V overnight. I’m amazed it could go so high. Is that typical?? Although it’s interesting to note when my grid charge does kick in around 2/3am how much it impacts the line voltage itself. I’ve got the installer coming out for an unrelated issue in the next few days. I’ll definitely get him to suggest how to deal with it.