OP
FB.
I have had my system in for one week now and we have made over 20kw every day except Saturday. Total for one week is 136kwh. We made 26kw yesterday which I thought was pretty good. I am really interested to know what the highest generation that can be seen in a single day from a 4kw system? Its only mid spring so I am keen to know what we could reach. My system: 16 x 245watt Sharp panels, Sunny Boy inverter and system size of 3.92kw
I have a very rough "rule of thumb" which says that the average daily generation for a system will be a bit less than half on dull days and a bit more than double on sunny days.
So if your monthly target for June is 420kWh, that'd be an average of 14kWh per day, so half that woudl be a bit below 7kWh on the dull days and double would be a bit over 28kWh on the sunny days.
Note that monthly targets for spring/autumn are only averages, since the day length is changing rapidly. At the end of March, it might be prudent to average March and April numbers to see what you ought to be generating.
You don't mention your location, your roof facing or the roof slope.