FoxESS Community - Owners & Installers Forum

Hi all, hoping someone is able to help. Have been chatting with the installer and can’t seem to work out what the issue is.
Our setup has a single phase inverter for our 6.6kw solar panel (even though we have 3 phase power). We’ve had our 3 phase foxess cq7 20kw battery installed with a 3 phase inverter installed for the battery. The solar panel inverter was not removed.
After the install I’ve been monitoring the usage and set time for forced charge and balance as Self Use mode. I’ve noticed on my electricity retailer app that during the night the battery will discharge and feeds back to the grid. It’s been happening since the install last week. I’ve currently had to set it to back up mode between 11pm-6am so that the system doesn’t discharge the battery completely back to the grid. I’ve been losing approximately 4-5kwh each day as I can read this from my electricity retailer app. Strangely the Foxess app is only showing less than 1kwh going back to grid.
Another strange thing that occurs is that during forced charge during the day, my home usage shows negative values occasionally which is weird.

Any help or anyone else experiencing this?

It sounds like the meter (or at least one of the CT's) have been fitted facing the wrong direction if the battery is dumping to the grid whilst set to Self Use, the negative load may be the same thing but it can also be if your installer has not fitted a 2nd CT clamp to monitor the output of your single phase solar inverter.

it would be helpful if you could post the home page of the app (with the image of the house) when solar is generating and also the app statistics graph, click on 'Daily Production' and screen shot the Statistics graph for a full 24 hour period.

Thanks for the reply Dave. I’ve attached some images from the foxess app for the 23 July. The app doesn’t appear to show much discharge back to the grid, I’ve had the battery to force charge up until 4pm at which it starts to discharge for self use.

I’ve attached a graph from our electricity retailer which shows the feed back to the grid from 4pm onwards, up until the battery runs out. It almost appears that when we’re using the battery part of it goes back to the grid as well. I’ve tested on setting the battery on back up mode during the night to stop the battery from discharging to the grid, and checking the electricity retailer app, that seems to stop discharging back to grid as the electricity retailer graph doesn’t show any power going back to the grid as soon as my battery is on back up mode.

The solar going back to the grid is through one of the phases, could it be that it somehow reads the battery as solar as takes the power back to the grid?

There is the image that you asked for during that same day on the 23rd July while we have solar charging, this shows the house being negative

It’s now during the day solar is charging the battery, I’ve swapped between the forced charge mode and self use mode and this is what I’m getting. See images