KH10 Grid Import during ForceDischarge period after FD SoC% reached

[mccraigmccraig]

Hi,

I've got a Force Discharge rule which is set to trigger during our afternoon peak period 16:00-19:00 ... it's currently discharging the battery down to an FD SoC of 50%, with an FD Pwr of 10kW, while the inverter has a Max Discharge Pwr set to 6kW, so there's a few kW overhead for the house load

This is fine while the Force Discharge is happening, but once the FD SoC% has been reached and until the end of the configured Force Discharge period, any house load seems to be drawn from the grid

e.g. see the attached chart from this evening - FD SoC% was reached around 17:30, and we cooked dinner around 18:00 and all the house-load for cooking came from the grid, which has certainly reduced any profit from selling power during peak times!

I don't want it to work this way - once the FD SoC% has been reached, I would like the house load to be drawn from the battery, otherwise we are paying for power at the most expensive time of day

Is there any way to make this happen, given current inverter config options ?

I can see two less than ideal options:

* lower the Max Discharge Pwr so that we never quite achieve the desired depth of discharge - this isn't ideal because it reduces the profit we would make if there was a good solar day, and we are still generating while discharging. It's also a bit rubbish, because if I want house load to be sourced from the battery during FD, then the actual FD power must be controlled with the Max Discharge Pwr setting on the inverter console and can't be changed from the app
* shorten the Force Discharge period - but also reduces potential profit on good solar days

Am I missing something better ?

Thanks!

[jonmjones]

I have same issue so watching this thread.

[mccraigmccraig]

@jonnjones given the lack of responses here i'm thinking there is currently no better solution

but I think this is an inverter software issue - the Force Discharge schedule _could_ be modified to either:

- terminate when FD SoC is reached, or

- draw house-load from battery, not grid, after FD SoC is reached

so I guess I'll see what Fox have to say... any clues on how to contact Fox support are most welcome

[chubber]

Apologies if you know this, but if you have FD SoC is 50% make sure your Min SoC for that slot is be set lower than this then it should use the battery?

[mccraigmccraig]

Hey @chubber ,

It's always good to check assumptions!

Here's my FD schedule that ran yesterday evening: Min SoC is set to 15%, while FD SoC is 75%:

and here's the timeline:

where you can see shortly after the Force Discharge rule finished, when it hit its FDSoC, the house-load is being serviced from a Grid Import. Once the Force Discharge rule's time-period has elapsed, house-load goes back to being serviced from the battery

I'd be very happy to learn I've done something dim, and that there's an easy solution!

:craig

[chubber]

Yes I would have thought you have that set ok. Although you are producing solar at this point so I wouldn't have thought that it would use much battery. May just be a blip of grid usage. Sorry I can't help more than that.

[mccraigmccraig]

It's better now I've started shortening the Force Discharge period to roughly match the expected time the discharge will take... before I was doing that it was quite bad - here's a week or so ago - it was a terrible day for solar, but without the import at peak times we would probably have been quite close to break-even

[chubber]

I've just verified this issue. Did a force discharge to 80% and rather than using the battery it used grid power for the rest of the slot to keep it at 80%. Looks like it is an issue with the latest firmware as it didn't use to do this!