Jump in house demand when forced discharging

Hi folks, wondering if anyone else has had this, or might know a cause...

I kept having bms under voltage notifications, pretty much every day.
I got in touch with givenergy and they updated the inverter (HY3.6) to D0.307-A0.307 (which has reduced it down to around one a week).

Since the update I've notice the following issue...

I'm on octopus flux, so I charge the battery fully in the early hours of the morning, then discharge it back to the grid between 1600 - 1700 hours.

I've noticed the amount of energy the house is using is artificially high whilst the battery is discharging.

For example, whilst the battery was discharging the other day, the house was using 886 watts.
When I stopped discharging, the wattage the house immediately dropped to 486 watts.
The instant I put it back to discharging, the house immediately went up to using 908 watts.
Nothing electrical has been switched on over that period to account for the extra wattage.

I have tried this several times over the last few days, making sure no additional electrical appliances are switched on, and had the same result each time...the house demand goes up around 300w when discharging the battery.

I've been in touch with givenergy but the service desk engineer couldn't figure it out, I'm waiting for another engineer to try and work out it.

I see the same, I put it down to overheads int he conversion process - as we're always taking more from teh battery than we're using. We know the conversion process isn't 100% efficient, so I guess the harder you push it, the more those losses show.

TimI

I know what you mean. The bit that concerns me is the service engineer didn't think it would be happening and Beirut did his colleagues when he asked them.
Strange!

One of the settings in the app is to show calculated load - I think what this does is just lump any differences between the various power readings into "house demand", just to make the numbers add up.

As above, I think it's probably inverter load - assuming you're discharging at full power, losses are possibly around 10% which would be of the order of 300W.

DD
Makes sense.
I reckon you should apply for a service engineer job at givenergy! 😂

@DD is correct. If you turn on ‘show calculated load’ in the app, the inverter will add any conversion losses to the house load so the “numbers all add up”.
If you turn this off you’ll still see the same discharge rate, export rate, etc, but the numbers won’t align as the conversion losses are ignored. Your house load won’t jump though

geoffreycoan
Thanks mate, much obliged