Problem getting +import/-export eco mode working on openevse

Hi, I’m new to openevse. I have built mine from the kit which is working really well. I bought the unit to replace my old chargemaster unit as I wanted to better use my solar generation and the ability to divert.

I understand that the eco divert mode works by MQTT from the ct clamps from my emonpi. I can get the use solar generation to work by setting emon/emonpi/power2 MQTT command with power2 being my solar generation. This works with the openevse starting when my solar PV system generates more than 1400w.

What I can not get to work is the excess only feature. If use power1 I only get my home energy use and not what I’m exporting so I never get a negative output on my ct1 so eco divert won’t start.

From what I see is I need a power1 minus power2 but I don’t know if it’s possible to do this or if it’s a limit of emonpi to provide the data. There is a power1 plus power2 line in emonpi inputs, can I add another input, virtual in effect as the emonpi only has to ct inputs.

I would love to be able to get this feature to work, any help would be much appreciated.

Hello @Rjallan21 There is a publish to MQTT input process that might work for your requirement. If you subtract power2 from power1, then publish the result to MQTT with a topic of the form emon/solarpower and then subscribe to that on the OpenEVSE that might work

I sort off tried to do this but don’t know how to do it without causing a problem with my energy monitoring.

I assume you mean add this in on the inputs page on node5 emonpi, power1 line?

I finally sorted this, as @TrystanLea said i added a publish to MQTT line in inputs.

It’s a shame there is not more explanation about how to integrate the openevse with MQTT and emonpi. It’s is assumed you have a good knowledge of how the UI works but I found this to be very vague.

Being that the solar divert is a brilliant feature of the openEVSE it is so frustrating to setup. Perhaps the emonpi setup template could incorporate an MQTT command at setup then if you add an openEVSE this functionality would work very easily without having to tweek up the inputs.

@Rjallan21, do you fancy writing up what you did and what you found? Part of the problem is not many people try it and it needs to be those that succeed who create the documentation.

@glyn.hudson this might be good to add to the OpenEVSE guide

All that’s required is if you want to use the divert excess solar power function and you have a type1 configuration on Emonpi you will need to add the following line in the inputs section for power 1 (assuming power1 ct is your use)

The way emonpi is setup for energy monitoring is that you subtract power 2 from power 1 to get your import / export figure.

The problem with the setup guide is there is no explanation how to do this.

To get this figure you need to go to:

Your local Emoncms

Go to inputs

Go to node 5 (Emonpi)

Click on the spanner symbol

Then on the drop down menu select publish to MQTT

Then add a name such as emon/emonpi/solarpower

Then click add

Then move this up by clicking on the arrows until it is before allow positive.

Click save changes

Then go to openEVSE

In services in the MQTT area

Delete anything in use all solar power

Then in the use excess solar power (import+/export-) box below enter emon/emonpi/solarpower and press save.

To check this worked then go to the manual/eco toggle switch on the main page of openEVSE and you should see a positive number if you are importing energy and a negative number if you are exporting continuously updating. (If it’s dark or overcast it will be positive.)

If you have a type 2 setup on emonpi you simply use emon/emonpi/power1(assuming power1 ct is your use) in the box instead of emon/emonpi/solarpower in openEVSE and you don’t need to to change anything in the inputs section of Emoncms.

Hope that helps. Hopefully someone can polish this up to add to the openEVSE setup guide.

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Thanks, I’ve added this info to the evse setup guide OpenEVSE / EmonEVSE Setup Guide - Guide | OpenEnergyMonitor

Thanks for the acknowledgment.

I think I’ve got it, by George I’ve got it! Thanks so much for your explanation.

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