Fronius Symo | PV API integration

Ricardo Pinto 4 years ago in Devices / Http updated by André Altjõe 3 weeks ago 5


I've successful integrated PV solar system from manufacturer FRONIUS in bOS.

More info coming soon... follow this post for more information.

Best regards


Sorry for the offtopic post. I will delete it if you don't want it here, but...


I'm having trouble with two Fronius Eco 25's. Thought You might know what i'm doing wrong. 

The inverters installer, gave me RTU output, they left fronius modbus settings to default( RTU export, baudrate 9600, parity No, string offset 101 and float selected). But I can't get any responses from it. Cas modbus scanner sees that there are devices with address 1 and 2 but i only get 0x02 - ILLEGAL DATA ADDRESS errors when i try to request values from them.

They didn't put it on the lan either, so its hard for me to test or change the settings on the PV inverters, i need to go on site for that.

Also the switch for the devices slave/master was left on Master. I'm not sure if this messes up the inverters communication between themself if its in slave mode or not. I'm thinking that if it's in master mode that might be the reason its not responding to requests.

Best regards,


Hey there Jürgen,

I'm very sorry I can't help you with this, as my integration is done through Ethernet API directly, on Symo model.

I've never implemented any Fronius with Modbus RTU.

Sorry mate! Hopefully someone will give you any hint on that.

Best regards


I actually got it working with RTU. Basically the template works just fine, all you have to do is add 400 or 40 before every register nr(I thought i tested this first but turns out i didn't... doh). I will need to recheck if all the values are correct but at least i now get some responses. AC side looks fine but on the DC side it wont report Voltages or current, this may be because we have more than one inverter and i dont know how many MPPT's they have there, and the manual says that: DC current/voltage only if one MPPT available; with multiple
MPPT “not implemented”

Hi! This thread is 3 years old, but maybe somebody has made some updates? I have tried to find a solution to trigger Dynamic Power Reduction (limit energy to grid) via Comfortclick. It seems that the API connection only allows to read information, but Modbus TCP would allow to send some commands too. Has anybody looked into this?

Image 4544