question

ponzoa avatar image

AC Coupled Fronius excess to activate over heat command to heatpump

Hi,
I have a Cerbo GX with a DC Coupled SmartSolar MPPT 250/100 (VE Direct), an AC Couple Fronius Primo 8.2-1, and am waiting for my Multiplus II 48/10000/140-100 230V. Batteries are 9 x US3000C Pylontech providing nearly 32kWh connected to the Cerbo GX via CANBus.

I recently installed a large Samsung Heatpump/Aerotermia which provides hot water and central heating. This Heatpump can accept commands via relays or Modbus to increase the heat of the water and central heating (when activated) by some 5ºC when excess solar is available to avoid or reduce night power draw from the grid.

The question is how do I configure or set this up?

On the relay side, it requires two relays which would work with the following commands;
Relay 1 Relay 2 Heatpump operation

closed open forced thermo off operation

open open Normal operation

open closed Heating/DHW setting temperature 1 step-up operation

closed closed Heating/DHW setting temperature 2 step-up operation


Can I use the 2 relays on the cerbo GX for this operation or would MODBus be a better option as I plan to incorporate a Genset to this later?

system integration
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3 Answers
Nico Bayer avatar image
Nico Bayer answered ·

Hi

I have nearly the same application. When my battery is full, i want my heatpump to increase the temperatur. It hase the same relays.

I do it with a separate raspberry pi running codesys. It gets all the information from the cerbo over modbus. I programmed it to open and close the heatpump relays based on battery state und some other conditions.


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Nicholas Herbst avatar image
Nicholas Herbst answered ·

You'll need to interface with the two different systems via their available protocols and control them through a management system/script.
The Cerbo GX you can communicate with via MQTT or Modbus. You stated your heat pump has Modbus capability.

I have fairly limited coding capability yet my experience with Home Assistant, running on a Raspberry Pi, was pleasant and intuitive.

I would recommend you give Home Assistant a try.

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I looked deeper into the Home Assistant and it seems pretty impresive. Would I need external relays or other hardware to be triggered by the home assistant and how would this be connected? My system works on normally open, normally closed combinations of 2 relays.
ponzoa avatar image
ponzoa answered ·

Thanks guys.

I found out today that MODBus cabling needs to go to the heatpump (complicated 45 meter cable run) but I already have the relay cabling done to my Cerbo GX which is near the indoor Hydrokit.


Is there any way to control those 2 relays on the CerboGX so I can take advantage of excess solar once the batteries are charged? Or is it only going to be possible using a Rasberry Pi or similar. Perhaps connecting with the Fronius Primo is an option?


If I use Home Assitant, I still have the same doubt. How do I tell the Home Assistant that my batteries are full and I have an extra 4kW of solar (for example) that I'm not using? My ideal would be to use the CerboGX and keep that as the central brain of my system (or the Fronius as plan B) as it's a Demo Site I've built and will be showcasing to new and existing customers.


Cheers,


Andrew

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Hi
Have a look into Venus OS Large. I've not tried it myself but maybe there is a way to control the relays with node red based on PV power and SOC.
https://community.victronenergy.com/questions/73741/venus-os-large-node-red-and-signal-k.html