We would describe that in kW. We don’t really use the term “kW peak” in normal parlance in the Australian residential solar industry, but you are correct, that it what we are referring to.
The 6.5kW and 10kW figures we refer to are “peak”, which is to say the cumulative nominal figure of all the panels installed on the roof, I.e an installation with 18 x 370W panels would be referred to as a 6.66kW system.
We have this post to explain the difference between kW and kWh