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pirx avatar image
pirx asked

Combining E-Car charging using a Wallbox with ESS

I think going forward this will be a very popular question: How to combine/integrate a Wallbox-Charger in/with an ESS System? What I'm not looking for are answers like: use the internal relay of a MultiPlus to turn on the charger when the ESS Battery is full.

It should be a smart integration in which the user can dynamically set the priorities, like:

1. charge the e-car using the remaining PV-power (ESS battery has 1. priority)
2. charge the e-car using all available PV-power (ESS battery has last priority)
3. charge the e-car as fast as possible

Options 1 and 2 would mean that the charging performance is constantly changing.

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Possible solution: use an external control unit which communicates with ESS and the Wallbox via Modbus. A control unit could be an OpenHAB system. I'm using such a system successfully for my smart home... A programmable Wallbox could be KEBA P30 x-Series.
The idea is to write a simple script which constantly reads some ESS figures, calculates the remaining power and sets charging power within the Wallbox. Option 1 could be realized quite easy, I guess. Any objections? Option 2 is more complex, but I think it could be solved as well. Option 3 is done without involving the ESS.

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Now, the big questions are: has anybody out there done this task already and can share the solution? if not, what other ideas do you have to solve the above challenge?

Many thanks in advance!

ESS
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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi @Pirx,

For now I have moved your question over to the modifications space. The users in modifications are more familiar with the kind of advanced controls you are looking for.

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jbakuwel avatar image
jbakuwel answered ·

Hi Pirx,

I wrote a rudimentary R&D Python script running on Venus here that dynamically adjust the EV charging based on a number of different factors: available (excess) solar energy, SOC, time of the day etc. I'm working on including weather forecasts for the next couple of hours (for example cloud cover for the remaining part of the day would be useful).

The script publishes a value (using MQTT) that is used by the EV charger to dynamically adjust the charge between 6A (minimum) and 16A. In my case I'm using an OpenEVSE charger (https://www.openevse.com) for the R&D.

Future versions will likely include a web interface to control it, the ability to heat a hot water cylinder (another "battery" after all). And once it all works I hope I'll have time to rewrite the software into something proper and publish it.

cheers,
Jan

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honzakr avatar image honzakr commented ·

Hi Jan, I am interrested to your code, but my device called simple EVSE. A communication is based on Modbus. Did you plan to use wetter forecast data from www.yr.no or www.windy.com source?

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pirx avatar image pirx commented ·

Hi Jan,

I'm sorry for reacting that late.... I'm highly interested in your script and especially in the way you have implemented it on Venus. Could you share it?

Many thanks in advance

Kind regards,

Pirx

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Petr P avatar image Petr P commented ·
Any news on this topic?
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paulcooper avatar image paulcooper Petr P commented ·
Hi. You may wish to have a look at what I’ve done. Search in this forum for “openevse electric vehicle charger”. I hope it helps you.
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juan manuel tirado avatar image
juan manuel tirado answered ·

Hi Jbakuwel !

I´m very interesting to apply excess solar power to heat wáter with a raspberry.

Could you publish your Python code ?

Thanks in advance!!

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jbakuwel avatar image
jbakuwel answered ·

Hi Juan,

I'd be more than happy to share the Python code that will control a HWC .... once I've written it :-)

Jan

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honzakr avatar image
honzakr answered ·

Regarding to me will be a nice option to be able to use the Victron managing computer (CCGX or Venus, etc.) to generate PWM signal for EV-charger (CP=ControlPilot signal). The EV battery is just a battery, but the charger work under big step regulation. I guess a DC Chademo/CCS 400V charging is for us out of the game, so DC__xV - AC_230V - DC_400V (2x 10% looses) charging works.
The question is always the amount of available energy delivered to EV (consumed). The system battery can be used here as system "balancing" device, as the car can be charged just in steps, not "on the fly".
The main question is, if is possible, to forecast approx. volume of "available energy" based on past supply volume. Total energy Solar yield earned minus energy locally consumed = (energy delivered to car + energy flow balancing/unstability correctrion). EV charger will give PWM signal based on on the fly energy volume forecast of future production.

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