Exporting to the grid in the evening. What is the reason?

Hi All

New to Solar PV so please excuse any daft questions I have!

Just had a 3.6kW Hybrid Inverter + 5.2Kw Battery (both givenergy) installed with 12 solar panels. Generally pleased with the whole setup but I have yet to wrap my head round the behaviour when it comes to importing/exporting to grid.

It is currently running in Eco setup but I noticed the house is running on the battery but also it is exporting a minute amount to the grid. Why would it do this given its night time?

You will see small amounts typically less that 20watts as the inverter switches between inputs.

Plus worth remembering that what you see on the app/web portal is a snapshot not real time.

Tolerances/errors in the system metering I suspect. Quite normal.

martinto8 there's a small "handshake" done with the grid periodically to check voltage & frequency, the inverter also takes a few seconds to adapt to load, so if your fridge comes on and then stops the inverter may take up to 30 seconds to respond to the lower demand and a small amount of energy will be exported for a few seconds.

Thanks all for the response! Makes sense!

I am also new to this and wondered about these characteristics. I came to the same conclusion as advised above.
I think that grid frequency and voltage also has a small impact on export/import. If you trend the grid parameters against home import/export when on full battery there is a correlation apparent. Not sure if it makes a big difference but I think there is an effect.

With these small little discrepancies as described above, I've been importing about 200 to 300 Wh per day. This equates to about 7p per day. Nothing major so I wouldn't worry about it as its perfectly normal.

My understanding is that the inverter polls the demand every 10 secs, and has to make a decision whether to make a change, increase or decrease to support the demand. The conversion from battery to ac, or any other change, is then carried out. It can't react instantly like the grid does. I've noticed that it can take 20 secs for the system to properly balance the load when my kettle is switched on, which represents an instantaneous increase in load of 3.3kW. I sometimes see the load fluctuating quickly by +- 150W, and the inverter does nothing, probably because it can't react in time. I hope this helps!

MF inverter polls the demand every 10 secs

I think the inverter is polling the import/export at a rate of many times per second. It does take several seconds for the inverter to respond to measured changes (ramp up/down) and the values stored in the inverter are posted to the portal every five minutes although the inverter does respond to local polling (from an app in local or GivTCP) as often as every 5 seconds. The inverter is responding to inputs really quite dynamically but the update times of 5+ seconds to 5 minutes to the cloud do interrupt it from its primary purpose of power control.