unexpected grid usage overnight

Hi ​@SolarSam , all inverters take time to process an increase in demand, increase battery supply and therefore remove the grid component. I agree that unless there’s a limit set for the switch over, it should be a minute or two at most.

If I read your graph correctly, the ‘pulsed’ slots are approx 200W and timed similarly to a fridge/freezer compressor switching on and off. During the day, solar PV is faster to take over so you are less likely to see this but it can still occur. 
Of course, it could also be something on the settings of your system which would need checking out but at 20p per day, I wonder if it’s worth the hassle 

The fridge freezer was my first assumption, and I understand that their maybe a spike of grid usage until the battery kicks in to meet the demand but I would expect that to be in the order of seconds, these pulsed slots are about an hour long, at a rate and quantity that should be easily covered by the inverter and battery, which has ample charge.

20p might not sound like a lot but it effectively increasing my standing charge from 60p a day to 80p a day. that a 30% increase. it equates to £73 a year.

What does your smart meter usage look like or your battery usage at those same points?

The smart meter usage shows a low load from the grid until sunrise and then it stops. It looks like the battery requires a kind of minimum load to switch on and the fridge freezer on it's own doesn't meet this threshold so just draws from the grid. I'm speculating, but if true that's pretty disappointing. If the smart meter is sensitive enough to register the load and charge me for it then I'd hope the battery would be sensitive enough to register it and supply it. Perhaps its some kind of battery protection software designed to extend the batteries life by preventing a large number of small discharges but in my view the point of the battery is to fill in the gaps when the array doesn't produce and so avoid using the grid altogether. If it doesn't do this then that's a big part of it's purpose not being fulfilled. 

In the graph below grey is grid, yellow array, green battery.

We don’t have the same system, but do see something similar although not as prominent. Just put it down to appliances myself, but haven’t checked in-depth. What is noticeable on ours is when we use the induction hob, which constantly switches on/off power. The inverter is not quick enough to smooth that out with battery supply, so we see spikey usage.

We don’t have Tesla unit so I’m not sure of the setup but if you look at your graph, it does give a clue along the lines you mention. 

On the far left hand side, one of the ‘pulses’ has an overshoot which is covered by the battery so there does appear to be a minimum level at which the battery will kick in. 
Surely there’s something to adjust that as I can’t imagine that to be fixed but you might need someone with good detail of the Tesla unit to get any further - unless your installer can help?

I do understand that the unit uses a ‘battery reserve’ setting but I believe that is more to prevent excessive draw when at low levels.