Self build ESVE. What bits do I need?

Am a newbie here so pls forgive the simple questions. I am struggling to find a full description of what the ESVE does beyond it’s datasheet.

I have a failed Chargemaster/Polar tethered ChargePoint that I want to upgrade with an Open ESVE PCB. I hope to use the existing contactor, car lead, etc. in this charge point. It is fairly roomy inside so there is space fit the Open ESVE stuff.

I’d need a Wi-Fi connection for the App. But how do I do solar diversion with my PV? Some other similar products only measure the PV generation and use that to decide the car’s the current. Instead can the Open ESVE account for house load and so reduce net export to near zero?

Looking at the shop presumably I need:

A display. Does the monochrome one come with the ESVE PCB as its in the pictures?
Some CTs although the ground fault one is out of stock. Will it work without this one?
Wi Fi gateway

Do I have to have an emon monitor too to transmit the export value to the ESVE or will a wired CT do it? If I do need one is the emonTx enough or do I need the full emon solution? That adds quite a lot of cost when I already own similar alternative energy monitors.

I have a Leaf with 3kW charger onboard and Octopus Agile.

PS The link to the user guide here About the OpenEVSE category seems to be broken, although I found it here EV Charging - Guide | OpenEnergyMonitor


I know i is extra cost but as you are on Agile and want to use solar divert the easiest option is the EmonPi solar version. This is what I have and it is very easy to then set it up as you want for the EV charging and then if you want to play more you can start adding lots more bits that listen to the Pi’s MQTT data and do things depending on that data, it can get quite addictive :slight_smile:


I must be missing something here. Once in a while we can get the car to charge at the same time the sun is shining but most of the time the car is then at another location because of work. Are we the only ones with this situation?

Antoine, I had that problem until I retired. Now the car is in the drive almost always especially in lockdowns. Mind you without the commuting one drives less so its becomes moot if the investment in solar charging pays itself back.

Presumably the info the charger needs is mainly the amount of export and maybe also the amount of generation. Where are these things defined in documentation? It is not impossible to generate an API/script or whatever to run on my existing monitoring to tell the ESVE up to every second the level of export and solar. Mind you at the moment that is well beyond my programming ability but I may be able to learn it.

Whilst one can get very into all this I find the problem is not upsetting the wife by saying things like “Sorry you can’t run that now as we need to wait till xx am when solar is high or Agile is cheap.” She is moderately accommodating but there are limits.

Thanx Frank, I see your point.

I would personally be more interested in some sort of arrangement where mqtt were to be used to stop charging at a certain state of charge.

And to start the charge at night. THIS is of course entirely possible in the current interface.

I know this is being worked on in combination with the open vehicle monitoring system.

But it takes a while. Wish I could pitch in more.

Best regards,


Met vriendelijke groet,

Antoine Maartens

MOB: 0 626 - 160 892

Verzonden vanaf mijn mobiele telefoon.

Misschien bondiger dan u gewend bent.
Op 23 jan. 2021, om 17:30, Francis Chan via OpenEnergyMonitor Community <[email protected]> schreef: