Ohme ePod Draining Solar Battery

[Vini]

My Ohme ePod is draining my solar battery, and despite logic within Home Assistant to try and prevent this, I'm struggling.

I found this recommendation

at https://fox-ess.tech/community/main-for ... hatgpt.com

But why does it require/suggest two Henley blocks?

I'm trying to enable my EV Charger to function using Solar benefits (excess export etc), but not drain the house battery. A common task, asked in 11897 different ways, I know and appreciate.

I have Solar, with Fox 7kW HYBRID inverter and Fox EP11 10kWh battery.

[Dave Foster]

You should be able to use HA logic to do it but it helps a lot if you have a shelly CT clamp fitted to the live feed to the EV charger, that way you have an absolute real time indication that it is charging.

But back to your question, you would expect every single phase hybrid to have the first henley block where the inverter and house load are connected, that is usually just after the live feed from the smart meter.

To have the EV charger ‘upstream’ of the inverter / house load so that it is not seen by the inverter you need to fit another henley block between the first and second henley blocks and the EV charger splits off there. That way the EV charger is in front of the inverter/house and it will not discharge your home battery, but the EV charger will be able to see any excess solar and use it.

[Vini]

If I can do it with a Shelly EM CT Clamp, I can probably DIY this and it would be cheaper than the Henley approach etc. The question is, will it definitely work?

Currently, with HA logic, if the Ohme calls for charge during Solar Excess, or IOG rates drop during the day allowing cheap charge, the battery gets set to 0A discharge and my whole house load ends up coming from grid. This feels wrong/expensive way of doing it.

[MaterialBarracuda48]

I had Octopus IOG and HA, using bottlecap Dave's Octopus add-on it was simple.
You have an automation setup to charge the battery at the same time as your EV (very useful in Winter)

Can you not just use this?

[Vini]

I had Octopus IOG and HA, using bottlecap Dave's Octopus add-on it was simple.
You have an automation setup to charge the battery at the same time as your EV (very useful in Winter)

Can you not just use this?

I don’t get this? Maybe I’ve described my issue badly. The issue isnt charging, but discharging.

I don’t want the car to discharge my battery. I’ve got no issues charging as such.

[MaterialBarracuda48]

By forcing a change of your battery, it stops the system draining of course.
It's actually a benefit to charge it on the cheap rate.

Just depends on your PoV of course.

Import at 3.5p kWh (7-9p now) vs. export at 12p it is cheaper to run your system this way.

[Vini]

By forcing a change of your battery, it stops the system draining of course.
It's actually a benefit to charge it on the cheap rate.

Just depends on your PoV of course.

Import at 3.5p kWh (7-9p now) vs. export at 12p it is cheaper to run your system this way.

My issue isn't at all with charging. I'm fine with charging my battery (both EV and Fox).

My issue is that if I connect my EV during the day, it is seen as normal load, and quickly drains the Fox Battery, resulting in expensive grid import (if the battery fully drains/solar is poor).

My desire is to have the EV load not visible to the Solar Battery, at all.

[Dave Foster]

What @MB is alluding to is that most people charge the home battery to stop it discharging because the EV tariffs vs Export tariff make it the most commercially economic way to do it.

You don’t have to charge at high power, instead of setting the discharge current to 0A, you could set minsoc to 100% and the batteries will charge at 5A (depends on battery volts but typically ~1kW)

The Shelly CT is just a way of detecting EV charge instantaneously rather than waiting for the tariff to change which is not the quickest or most reliable method.

But from what you have said if your objective is to power the house from solar/batteries and the EV only from grid import/solar the only option for that is to move the EV charger connection in front of the inverter/house load as per your original diagram.

[Vini]

This’ll do it… yeah?

[Dave Foster]

The only grey area there is where the inverter isolator joins the consumer unit, the ideal approach is as your first drawing i.e the consumer unit feed would be split before the consumer unit and the inverter connected there.

The issue with inverters being connected within a consumer unit is that depending on how it is wired, you can have voltages present on the busbar and the house circuits even when the consumer unit isolator is open.
Clearly there would need to be ‘Dual Supply’ Solar PV labels that warn that both supplies have to be isolated before any work is carried out but a significant risk exists.

[Vini]

I bought and installed a second, identical FoxESS, CT with the hope of testing out some "theory" I'd read about running a CT on the Car Charger backwards.

I installed this CT onto pins 5/6 in my KH7, and enabled CT2 - like this scribble. This achieved the square root of diddly... the CT was around the armoured cable running from CU to Ohme, and not the Live feed specifically - this could be part of the issue?

But I've since read that the CT's should be wired in parallel. I take this to mean both CT's into 7/8 on the Inverter. Is this understanding correct?

[MaterialBarracuda48]

AFAIK both CT Clamps should be wired up to CT1 location on your Inverter.
Original clamp will read house load as 'Home' & 'EV' for example 1kW + 7kW for a total of 8kW.

2nd clamp is wired in reverse polarity to your CT1 location on inverter, and clamps goes around wire heading to EVCP.

This should blind the load, as it now reads 8kW on original clamp, and takes away 7kW of EV, so that Inverter only supplies the 1kW of house load demand.

[Vini]

Thanks to you both MaterialBarracuda48 and Dave Foster.

After "understanding" the term parallel binding of CT Clamps, I seem to be in a better (if less than preferred) position.

I made a CT splitter, fitting a new stretch of wiring from pins 7/8 (CT1) on the Inverter, to a couple of Wago's. To which I added the original CT, and a secondary CT. The location of the original CT remained "as is" on the Mains Live in from the meter, with the CT arrow pointing back towards the Grid, and the secondary CT clamp round the feed to the EV charger, pointing towards the EV Charger (away from the grid).

In doing so, this seems to have confirmed what you were both saying and resolved my "EV draining battery" issue.

My EV is, as we speak, happily consuming the excess solar being produced, whilst the battery remains topped up/charging.

Another question, relating to this setup. Is my Inverter throttling the import/export rate in this configuration? I seem to be only able to get ~7KW import at any given time. I have a 100A mains fuse. The EV Charger is 32A capable and the Inverter is also ~7.xKW (theorhetically 32A). On the basis my grid link is 100A, my heads saying I should be able to run both together each at ~7KW. However, I seem to be limited to ~7KW. This results in the EV charging at ~16A/3.5KW ish...

If this is a limitation of the current wiring situation, then my now resolved issue is I guess, somewhat futile. But a nice win all the same. The next question is, if I did split the Car and CU feeds out via Henley, would this provide me with the maximum capable import (for my situation)?

[Vini]

Might have spoken too soon on the CT "fix". Battery dropped to 80%, but consumption wasn't immediately reflected in either the Modbus monitoring, or that of FoxCloud dashboard.

Feels like it worked for a bit, then sufficient excess solar ~5KW, kick started the charge, but as this solar gain dropped, the battery ended up kicking in to share the load to sustain ~3/4KW car charge - Grrr.

The fact it shows a >4KW load, still feels like somethings wrong... as you said MB, it should be House Loads minus Car Load, if configured correctly, no?

[MaterialBarracuda48]

The issue I see before when the EV Charger was setup to use PV spare energy, is when the clouds roll in, the battery would take over the load, thus draining it.

I didn't have the reverse CT clamp setup, but this was just how things went.
This might not be what is happening, but sounds like the EVCP is demanding power, and the battery is happily supplying what it sees as a load.

[Vini]

Yeah, that's almost certainly what happened... I think, however, I had the secondary CT clamp around the entire 3 core EV charging feed, which I have since learned to be totally incorrect.

I have moved the CT so that it is ONLY around the LIVE feed of the charger now and will be having another play.