How can I stop my Eddi from using the batteries to heat the hot water?

[risky_boy]

Hey all. I’ve recently discovered this forum and there are some brilliant people and solutions on here, so I’m hoping someone can help me… my solar installer was useless and didn’t really know what he was doing, so I’m learning all this as I try and figure out the system!

My question is "how can I stop my Eddi from using the batteries to heat the hot water"?

From the 3 images below you can see (at least I think that’s what it’s showing) that in images 1 and 2, you can see that the Eddi has changed it’s mode to “diverting”, but it’s clearly pulling electricity from the battery, and when the diverting stops, the battery state of charge remains level or increases again due to excess solar.








In image 3, it starts with what looks like the excess solar is heating the hot water, and then just after 5pm the batteries are taking over again.






All the data can be seen in the various apps, but I’ve used Home Assistant to pull all this data in so that I can see it all on one graph easily

I wondered if I could setup some sort of Home Assistant routine that if the battery is discharging quickly then change the Eddi mode to “stop” - I have a routine to stop diverting once the tank is about 80% full of hot water anyway, otherwise it just keeps on heating!

I’m sure there must be some sort of setting on either the Eddi or the Inverter to try and stop this happening.

If it helps, the bits that will probably be relevant to this question are:

• SolaX X3-Hybrid-G4 (10 kW) inverter (set to “self-use” mode)
• 4 x SolaX batteries (1 x SolaX MC0600 HV10230 V2 (3.1kWh) and 3 x SolaX HV10230 V2 (3.1kWh) = total 12.4kWh
• A MyEnergi Eddi is diverting power to the hot water tank (Mixergy)
• Hot water tank is a Mixergy, and there is a gas boiler attached to it also
• 3-phase power to the house (not sure if it makes a difference)

Thank you for any ideas!

 

[wattmatters]

https://support.myenergi.com/hc/en-gb/articles/6778001879569-Using-a-battery-with-your-myenergi-system

 

[risky_boy]

https://support.myenergi.com/hc/en-gb/articles/6778001879569-Using-a-battery-with-your-myenergi-system

Brilliant, thanks wattmatters! I'll give this a go!!!

 

[risky_boy]

Just as an update, this wasn't working for me on the recommended settings of 50W or 100W. I even found that the Zappi charged my electric car from the battery which drained it quickly. Then I did notice this in the documentation (which I missed last time)...

Please note - if zappi or eddi are "boosting", or zappi is FAST mode then power will always be taken from your battery, unless the battery is turned off.

Note: If you have the Export Margin set then, on zappi, the "Minimum Green Level" or "MGL" needs to be set at 100%.

I think I charged in FAST mode that day, and I hadn't set that setting on the Zappi (so that explains that). I've now changed that setting, plus found this solution which suggested that in some situations I might need to set the export margin to 150W...

https://support.myenergi.com/hc/en-gb/articles/4716922623633

Set the Export Margin to 50W and the battery should take priority over the zappi or eddi. (In some cases a setting of 100W or 150W is needed). Your myenergi devices will now wait until there is a small export before starting to divert power to the car.


I'll see how this goes the next few days!

 

[wattmatters]

I'll see how this goes the next few days!

Let us know.

Managing multiple controllable loads within the solar production curve along with home energy storage is an emerging challenge.

I use a PV diverter for our water heater and at some stage will have an EV for which I would also like to avoid importing grid energy. We have enough PV capacity to cover most of our expected charging demand, so it comes down to how smart the charging can be made to operate.

Myenergi is interesting in providing such solutions within the same ecosystem, but I guess even that doesn't always guarantee the desired outcome as they don't manage home battery storage solutions.

 

[risky_boy]

Interesting. Since making the above changes I think it's all working - so the Eddi doesn't seem to pull power from the batteries to heat the hot water anymore.

Here's some data from Home Assistant showing the battery level (purple line) and the hot water level (blue line). At the top of the screen you can just about see if the gas boiler was "on" or "off" and hence heating the hot water. The change was made sometime in the morning of the 1st.




As a side note, and perhaps as a result of having extra battery capacity (as it's not being used to heat the water), we seem to have pulled less electricity from the grid also since the change was made on the 1st (blue bars).





So hopefully that's all working now!

 

[wattmatters]

Glad to hear it's working better now.

and the hot water level (blue line)

What does "hot water level" represent? Hovering between ~5% and ~50% seems strange for a home's hot water supply, which typically would be fully re-heated 100% each day. Is this for a home heating system?

 

[risky_boy]

It's a Mixergy tank, so it shows how much hot water we have in the tank. Typically there is no need for us to heat it to more than about 60% of the hot water in the tank in the mornings for our house of 4. It's one of my favourite bits of tech in the house since we did a big re-fit, as before I had no idea how much hot water we had left... which was even more annoying if we had people staying with us and you want to make sure they don't have a cold shower.

 

[risky_boy]

Quick update. Looks like it's not quite solved, but working much better! Since making the change on the 1st August (setting the Export Margin to 150W) it looks good from the graph below that it's not used the battery (via the Eddi) to heat the water using the emersion heater. However today you can see (on the right hand side) that clearly the battery was being drained, yet the hot water level was increasing, even though the gas boiler was off - so it's only source of heat was the electric emersion element.

I've tweaked the export margin further to 200W and will monitor...