Max output questions

Newbie questions apologies, but today is probably the first day since my PV panels went up that I’ve had a constant 10/10ths blue sky from morning to evening. GE app chart snapshot looks like this:

I have 13x400W panels so 5.2kW theoretical max output (10 on a flat roof, 3 on a pitched roof) - and a GE gen3 5kW Hybrid inverter. My gateway and AIO are currently off as yet to be commissioned (fingers crossed for a successful GE site engineer visit booked for this week…)

The inverter today reported generating 3.9kW peak at 13:15, so 75% of that figure. There are also interesting discontinuities in the graph when generation steps up at 08:15 and 10:25 - perhaps spurious, or maybe due to panel location / orientation?

I would appreciate any input on

1) Does 75% peak generation sound right for early September?

2) The 5% difference between generation and consumption - is that due to inverter losses?

3) Is there a well regarded industry tool (that’s free?) for estimating theoretical generation given panel setup, location, time of year etc?

Thanks all - really grateful to this community for contributions thus far!

26Left Hot day, clear blue sky and no wind. Panels get hot which reduces efficiency and by quite a margin. I have 4kw panels and a 3.6kw inverter and I toppd out at 2.9kw generation. You will find you'll get the best performanc of the panels on sunny but windy days in spring and autumn. The wind helps keep the panls cool.

A lot depends on the panel orientation and tilt. Our west facing array (45 degree) hit about 75% of nameplate power at about 3.45pm.

The discontinuities are odd. Do you have a chimney or similar that's shading the panels at those times?

On a cold day I see 5.1kWp max from our array, today the highest was a tad over 4kwP. All down to the temperature.

Have a look on your solar panel spec at your NOCT output. 75% is a fairly typical noct figure. There's lots about STC and NOCT on google which might help give you a better understanding of how your panels are affected.

26Left The sudden changes at 8:15 and 10:25, if they happen every day, are probably caused by shading. I am not sure why there are two jumps but I certainly get the same behaviour at around 8:30 when the sun moves south of an oak tree and suddenly the whole array is irradiated. There's a lot about this on this forum in many threads but it seems to be to do with how GE's MPPT (maximum power point tracker) works and something about bypass diodes. I am still not entirely clear what the issue is, but it does mean you lose generation until the whole array is illuminated because the amount of current is clipped to whatever the minimum is across all the panels if the bypassing doesn't work properly. Some people fit optimisers to try to compensate, but others have different views and some criticise the GE algorithms.
Yesterday with a 10200W system peak generation never exceeded 50% but we still made 35kWh in total, and we've never managed more than 82% since installation three months ago.