Charging off grid

We've recently noticed a usage of 20-30p on our smart meter when we've been out in the evening. Having switched most things off tonight it seems that the battery has been slowly charging from the grid at daytime rate during the evening. Why is this ? surely the battery should discharge to run things? Also the battery does discharge when using electricity to heat water/charge car overnight but the battery will never discharge below 50%. Why is this ,it doesn't seem efficient?
Gary Mudd

Mudd The inverter takes a short time to respond to changes in load. The inverter output ramps up quite quickly but could take 20 seconds to go from idle to maximum output from battery when you switch a kettle on. Similarly, when it boils, the inverter exports to grid while it ramps down to idle again. Each morning I check the current day electricity consumption on my Bright App (which is the same data as the smart meter display at home) and it is usually somewhere between 0.2 and 0.4kWh and the total import for the day is usually between 0.5kWh and 1kWh, depending on what's been going on. A small daily import/export to cater for high-energy appliances such as kettle or oven is to be expected. Our overnight usage is due to the fridges and freezer automatically cutting in and out.

Mudd will never discharge below 50%

Are you saying that the water heating/car charge always completes before the battery reaches 50%? If you are charging EV and house battery overnight, it sounds like you have your Charge to % set to 50. If not, then more information would help to identify if anything's wrong.

Thanks Tim, I understand that response times with items such as kettle can have a dwell time.
I'm talking about the actual discharge of the battery when charged up. It is not set to charge to50% and its minimum is set at 14%. It is set to charge from solar as is required. The force charge overnight on off peak is off at present.
The battery charges up to 100% with solar in the day ok. It will discharge when energy is used during the day or night but only as far as 50%. We have noticed in the evening that the battery is charging from the grid at full price and I don't understand why this is or why the battery will only discharge to 50% . It is fine that solar charge in the day helps charge the car at night but not when the battery has been charged using full price electricity in the evening! \then it is better to charge from off-peak grid!
I hope that's clear.
Gary

Mudd I take it you have one inverter and that it's a hybrid (PV and battery), and that you have one battery connected to the inverter?

If so, maybe put it back into a known state? Portal - Inverter - Settings - RESET TO DEFAULTS - Submit. You should get a small pop up to say that settings have been saved. Doing that should switch off all timed settings, set the inverter mode to ECO. Check that this is the case (ECO enabled, all other timed settings disabled), then check your Battery Options: (Reserve - set to your chosen 14%, Usable 96%, charge and discharge power set to max).

See if doing that restores sanity.

Obviously, if your EV charges overnight, given the above settings, your battery will likely discharge to supply it. If you want to prevent discharge to EV, set a timed charge for the same window as your EV is set to and a Charge to % set to whatever you need to get you through to the next charge period (PV or off-peak). Alternatively, if it's convenient, just don't charge the EV for a couple of nights and see if the defaults result in the plant performing as expected.

Finally, some people have an Octopus tariff which takes control of the EV charging and can also affect the Givenergy inverter. I'm not sure how to switch this on and off if this is your situation but if it's not, then ignore this bit and just go with the previous. If that doesn't restore the status quo, then a call to Givenergy for help is in order (unless anyone else has any suggestions).