I seem to be getting weird constant interval power surges not necessarily at night but mainly at night and i also notice when looking at my solar app that it showes the house using ~4KW when the only thing turned on is my PC, fridge, security cameras. 

i would usually only see this usage if i was turning on a split system aircon or something.

I have attached an image for reference.  I have tried turning everything i can off in the house including the fridge overnight to see if this would solve the issue which it didnt, my house isnt that old and i dont have any old appliances.  My hot water system is an instant Gas system, there no timers for anything which turns things on or off, i dont have a pool, spa, water sprinkling system or climate control which would be on a timer or could self turn on.

I have a 6.7kw solar system with a 10.3KW battery and i'm still paying about $160AUD per month in Electricity. 

TIA

 

https://imgur.com/a/rh0IcDw

 

Any pressure control pumps perhaps? Any leaks in the pressure system would cause the pump to kick-in as the pressure drops.  Just a thought.