A friend showed me a quotation (well, he had several and the one was way more optimistic than the others)

He is getting 10 x 600 watt PV panels, a Deye 10kW inverter and 3 batteries

The spec states that the panels will supply 7kW of power all the time during the day.   It did not say whether this was the daily total of incoming power or what you get all the time

I thought that a 600 watt panel would perhaps deliver 550 watts on a good day but 10 x 550 watts is not 7kW

I spoke to the gent who issued the quotation and he started to get annoyed with my question, saying he has X number of years on the job and has installed Y number of solar systems, so who am I to question his expertise

This gent seemingly has information that the manufacturer of the panel doesn't even know of 🙃

Output peaks during cloud edge do sometimes spike above the panel specs, but definitely not all the time.
Just stick with the manufacturer's specs. That's what can be expected under ideal conditions. 

3 hours ago, chrisc said:

The spec states that the panels will supply 7kW of power all the time during the day.   It did not say whether this was the daily total of incoming power or what you get all the time

No way this is true.

PV production is usually shaped like a bell curve. So the statement that 'the panels will produce 7kW all the time during the day' will never be true. Then also factors like direction of the panels have an impact on production.

I am also based in CPT and here is the production data from my strings from this morning. Yellow is 6x 580W (=3.5kW) panels facing the morning sun and blue 8x 490W (=3.9kW) panels facing the day sun (main direction).

You can see the ramp-up on both string. The yellow one makes a steep jump around 07h30 as the sun comes over the mountain. And you can see the drops due to cloud cover on both strings.

By almost 11h30 neither string produces the nameplate capacity. So getting a constant production 'all the time' is just plain wrong.