FoxESS Community - Owners & Installers Forum

Good Evening,

I’ve in the last couple of days been transferred to an Eon Next Drive Smart Tariff, which as well as the cheap overnight charging between 00:00 and 07:00, if I use the Next Connect App, using the Tesla API it will now, when electricity is cheap, also give me the cheap 6.7pkwh rate at times between 07:00 and 00:00.

Today has been the first day it’s been utilised, and at 21:30 today, I was charging my vehicle taking advantage of cheap electricity.

However this has thrown up an issue, in the sense that as well as pulling from the grid, it’s also discharging my battery.

I’ve been able to get around this issue overnight by force charging the batteries between 00:00 and 07:00 effectively charging the EV from just the grid.

With the dynamic nature of the Tariff and cheap rates being made available at various, unknown times throughout the day/weeks, is there anyway I can set up the battery in the settings to not discharge to the EV, and for the grid to pick up the entire load?

I hope I’ve described the problem clearly.

Any help, would be greatly appreciated.

Many thanks

The easiest way to deal with this is to make sure the EV charger is connected in front of the inverter so that the inverter does not see it as house load and won’t discharge the home batteries into it. This could require a bit of re-wiring (usually a henley block) to split the feed to the house / EV charger - sometimes you may be able to re-position the inverters CT clamp so that it doesn’t see the EV.

You can set a charge period for the same time as the EV charger is charging with the ‘charge from grid’ disabled, that will not charge the home batteries but will also stop them from discharging as well.

It is possible to use a home assistant to do this programatically whenever it sees the EV charging it sets the battery to stop discharge but there is quite a big learning curve ahead of you there unless you are considering that anyway - which is why I started with the easiest solution is to re-wire it to split the feeds.

I’ve only recently joined the community and have also just moved on to the E.ON smart tariff I am experiencing the same issue as the original poster. I’m certainly interested in exploring the Home Assistant solution and would appreciate any detailed information that can be provided on this.

Johnso wrote: ↑Wed Apr 22, 2026 10:05 am I’ve only recently joined the community and have also just moved on to the E.ON smart tariff I am experiencing the same issue as the original poster. I’m certainly interested in exploring the Home Assistant solution and would appreciate any detailed information that can be provided on this.

You need either some 'add-on' to Home Assistant that can read the smart meter (Octopus has Bottlecap Dave's add-on) or something that can read your hopefully smart charger.

You also have to have communications to your Fox Inverter, this can be wireless/hardwired/cloud based
1. Some inverters have WLAN baked in, along with Modbus support
2. If not, then you can wire in Modbus support for supported inverters
3. Have a good read of this thread viewtopic.php?p=15707#p15707

An overview of what you could achieve
viewtopic.php?p=6565#p6565


It might be a good idea to post a picture of your electric meter box area zoomed out, so that we could look at wiring.
If you have the correct Henley blocks already fitted (to split the EV load before house load) then it could be a 2 min task to simply move a CT clamp and problem is fixed.

Another cheap way, is to fit a 2nd CT clamp on the wire going to the EV charger, in REVERSE orientation, and wired to the inverter main CT wires, so that it deducts the load and it become 'invisible' to the inverter load.

Thanks very much for the wealth of information that I am working through and trying to absorb. I’m a novice in this area and there is a lot to take in. From what I’ve read so far a HA green based solution looks promising provided that E.ON provides real time data on prices.

You asked for a picture of all of the components of my installation and this is attached.
The inverter is an H1-6.0-E
Battery is ECS2900, just a master and slave.
EV charger is a Zappi v2 and there is also a Harvi

When I spoke to the installers about this issue they suggested that the solution would be in the configuration of the Zappi so I raised a ticket with Myenergi but have received no response. Everything that I have read in the meantime suggests that it is actually about dynamic configuration of the inverter/battery using an app like HA unless the simple CT clamp solution that you alluded to is possible.

How does the Zappi get power?
Is it coming off your Consumer Unit?

Yes that seems to be the case. Two cables from the original consumer unit (plastic) to a small secondary metal consumer unit and from there a cable out to the Zappi.

Johnso wrote: ↑Thu Apr 23, 2026 3:38 pm Yes that seems to be the case. Two cables from the original consumer unit (plastic) to a small secondary metal consumer unit and from there a cable out to the Zappi.

I believe user Grumps went with the 2nd CT clamp solution...

There's a fair read here regarding the possible CT clamp 'adjustment'
viewtopic.php?p=13856#p13856

Thanks for the further input. As I build a better understanding of the subject I’m more inclined towards the HA based solution. I believe that it preserves the integrity of all data being reported through my current apps but also means that I can top up the Fox battery during the day and maximise the power sold to the grid. Currently there is a big differential between my off peak and SEG rates, the former just under 3p and the latter at 16.5p.

I’m reading that there is an established integration between HA and Zappi and this may be a better option than linking to E.ON. Hopefully simple logic of if Zappi charging then set work mode to forced charge should work.

Johnso wrote: ↑Thu Apr 23, 2026 5:22 pm I’m reading that there is an established integration between HA and Zappi and this may be a better option than linking to E.ON. Hopefully simple logic of if Zappi charging then set work mode to forced charge should work.

Yes there are some HA controls for Zappi, one called 'status' with a few values: Boosting / Paused / Completed
You can check the HA logs after a charging session and read the values to see how it all interacts.

Suspect this might be the one you are going to need to listen to in HA to adjust the Inverter state.