Actually the rating's not for "Sahara at noon".
It's for 1Kw/m^2 at 25C with the panel facing the sun.
You can look up the insolence for your city, they even have annual insolence averages which accounts for latitude, hours of sunlight per day, average cloud cover and dust, and seasons.
Sunlight at southern latitudes, on clear days, can exceed 1Kw/m^2 easy.
However, there are many factors to degrade the output:
The sun being reduced early and late in the day
The sun being reduced in seasons other than summer
Cloud cover, or dust in the air
The angle of a fixed panel not adjusted for seasons
The angle of the panel not tracking the sun
The glare off of the clear panel material covering the cells
The panel being dirty
The panel being >25C. This is quite significant, and few panels make any meaningful provisions for cooling the cells in the sun.
Panel degradation (can be 10%-15% in a few yrs exposure to sun after mfg).