What power company are you with. My power company has stiffed me big time. My bill went up by $400 with a 5kw system. I think they added the solar instead of taking it away. My neibour with the same system and power company has the same problem. next step Ombudsman.

What was your average daily use ( is on your bill) and what is your average daily electricity amount generated??

We use on average 21KWH per day and are generating average of around 25KWH... we still have to think smart though and use as much as we can during the day when we are producing as we buy electricity at 28c per KWH and the excess we sell we get 18c per KWH.
So its important to have a nice wide margin between what we have imported and what we have exported in order to attempt to reduce our bills to close to zero