EVSE Control charge rate

Hi All,
I have the openEVSE connected to the HEMS now via MQTT (thanks for the smooth remote setup!).

As well as the powershaper events, I was hoping to be able to use this to manually toggle charging myself, or based on automations.

I have managed to create basic on/off automations, but really would also like control over the current, IE lower the current when the EVSE gets turned on during the day, so I can balance against solar output.

I know the functionality exists, as per: https://www.youtube.com/watch?v=tjCmPpNl-sA&t=1s&ab_channel=GlynHudson

however the available MQTT options only show the charge current as a sensor. Any Ideas?

Many thanks

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We havent exposed charging rate in UI (yet) but the EV charger supports this via MQTT/REST API so can be done in HA (or otherwise). As PowerShaper participant you have a new version of the charger which has slightly different MQTT topic scheme (this will become standard on emonEVSE chargers in future). This is described here:

Thanks Ben,
being a novice to MQTT, how do I “add” this option or alternatively how I can create an Automation that sends the right MQTT message?
Ideally I would limit the current to 13A during the day, then back to 32A at night

I have added two automations on your HEMS which should do this. Take a look at see if they work. It may need some further tweaks as I may not have got the payload/topic quite right but its in line with the MQTT API description.

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Amazing thanks Ben, I see how it works now.
Lots more to play around with now!

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Oh dear, I refreshed the Automations page and all automations besides the two you just created have disappeared! I haven’t deleted anything so not sure whats happened there - edit: they have reappeared, wasn’t sure if you had done anything

Hi This is still something I need to add to my OpenEVSE / HEMS setup.
Will speak to you about it later this week if we get chance.

Hi Ben

this is something I also want to do. I have temporarily decommissioned my Zappi for the PowerShaper trial and this ability to balance the charge rate against available solar surplus is one of the things that I miss the most. If you could tell me how to add the automations that would be grand!


Sharing automations like this might be something we could use the new Home Assistant Blueprints feature for.
I hope to release that update to HEMS this week.

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The EV charger supports solar diversion out the box, it just needs to have a measure coming in of the excess power (above your house consumption) or grid export power via MQTT (or anything you like really) so it knows how to adjust charging rate. This is what is referenced in the emonEVSE UI as ‘eco divert’. But first you need to get that bit of data.

Its a shame that the monitor and hub that comes with zappi systems is so locked down otherwise we could get it off that (but that is sort of part of point of this project to try to have a system which will interoperate with other systems etc.).

There are lots of devices which could do this otherwise and we are interested in testing it out. I would be happy to supply you with something free which you can plug in to do this from the stock we have left over here. You just need a plug somewhere near to the incomers to power it. The setup will be similar to the relay controller plus another automation which will map the MQTT messages onto what the EV charger wants. You could then also exert some control over this from the HEMS and do things like prioritisation.

I’d be up for giving it a try.
I have the CT clamps from the Zappi, if that helps.

Its possible they would work but ill send you some new ones with it. Isnt going to be before xmas but might be able to get in post next week before i go on leave.

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What solar inverter do you have? it might already have an integration to Home Assistant, I saw mine in there, Solar Edge.

This is also option but we have someone else in trial trying to do this but Solar Edge API is well know for being quite flaky. There is also maybe a local network API supported by HA but my understanding is that this only ever worked on particular models and SolarEdge have in recent firmware updates disabled it.

I’ve got the SolarEdge API working but dont know where to go from there to drive HA automations using that data.

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The other issue which i completely forgot about is that there is a delay on data coming down from solar edge API which may make it not very useful for this purpose.

I can take a look at your automations and try and at least put a template in you can edit.

I have found that with solar edge as well, now I use the Tesla powerwall to tell me the generation

Mines a SMA Sunny Boy 3000

https://www.home-assistant.io/integrations/sma/ This shows how it can be added to Home assistant, however I think this isn’t available on the HEMS, maybe someone from the Carbon COOP team can add it?