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Would it be possible to control a MultiPlus II via MQTT ?
What I'm thinking is to disconnect the mains in relay off between 16:00 - 19:00 this would be because on the Octopus Agile tariff here in the UK is the very expensive period. During this period my house would run from batteries via the inverter in the MultiPlus II. The control would come from Node-red.
Might be possible with a raspberry pi running Venus OS, that has the MFD option via MQTT. You might be over my head, maybe I'm just adding noise here.
Dunno about MQTT but with Venus OS and dbus, you could perhaps achieve this by setting the current limit to 0A in /Ac/In/1/CurrentLimit.
See more: https://github.com/victronenergy/venus/wiki/dbus
Doing this soon. Will be fitting a Color GX so have the option of using the generator start relay to control a mains contactor via the quiet times setting to inhibit start or in this case grid in.
Or I have also ordered a smart plug that can be set via ITTT to switch on / off as the price set point rises & falls. The plugs have a 16 amp capacity but again I would wire via a contactor for robustness. This would allow me to fine tune charge times to only when below x pence per unit.
this is easy via node-red:
Ah oh that looks easy, so you can MQTT directly into the MultiPlus II ?
What MQTT path are you writing the System Mode too? I've tried N/myid/vebus/257/Mode but it doesn't seem to take. I can read from there without issue but writing a message to that path appears to go unheard.
Thanks
In answer to my question;
https://github.com/victronenergy/node-red-contrib-victron#Installation-and-Usage
~/.node-rednpm install @victronenergy/node-red-contrib-victron
found some examples you could use
https://github.com/victronenergy/node-red-contrib-victron/wiki/Example-Flows
The following flow tries to maximise the electricity cost savings by charging the batteries only during night time -- unless the battery level is critically low.
For simplicity I would put a standard digital timer on the ACin and limit the ACin current in the Multiplus to slightly lower than the curent maximum on the timer which is usually 16amps. Use power assist to get the batteries to compensate for spike demands higher than 16amps for short periods if you are using a 5kva unit. The 3kva unit should already be protected by a 16amp MCB.
I would not want to run a 16 amp device at 16 amps for long periods. Also the time that the energy is cheap changes on Agile so you need a more active device to track that. On Octopus's other tariffs its fixed rate periods so that could work but you only get 4 hours cheap rate.
My two units could draw nearly 30 amps if both were set on max.
The smart plug has arrived but it seems that if you are not already on Agile you cant access the data to use IFTTT to test it out.
