I'm from Latitutde: 31.52 and houses here have flat roofs. So we have to mount panels on angled structures on rooftop and obviously have to add row spacing to avoid shading. According to pvwatts the optimum solar panel tilt angle for my location is 24 degrees. 

The problem is that for 24 degree tilt, we have to add a lot of interrow spacing, which wastes space on roof. With 24 deg tilt, max I can get 10KW panels on the roof. So I tried with 0 degree tilt(i.e. installing panels flat on our flat roof), and obviously there is loss of total power generated. But, because of no shading issue, I can easily fit 15KW panels on the roof, meaning the total output of system is still significantly higher. 

Assuming price no issue. What do you guys recommend, have fewer panels at optimum angle and waste space OR install flat or maybe very low angle like 10 deg and install more panels?

Numbers:
10KW @ 24 deg = 14,554 kwh/yr
15KW @ 10 deg = 20,921 kwh/yr
15KW @ 0 deg = 19,678 kwh/yr

Edited June 11, 20224 yr by LionKing

I'd do 10° & 15kW, this should give you slightly  more in winter than the 0° 15kW variant, which is when your production will be at its minimum... I'm down to around 22kWh a day right now, as opposed to 33kWh a day in January, of course, this is when there are no clouds...

Yea, 10° makes better sense as the panels will clean themselves better after rain as well. How do I calculate min row spacing to avoid shading during winter months?

Found this: https://solar.sreda.gov.bd/irsc/

Reducing The Threat of Hail Damage to Solar Plants | Nextracker

Anybody know where to get raised frames? 

Late to this thread. I don't know South Africa suppliers, sorry.

But definitely don't mount panels flat on a flat roof; they need air under them for cooling. I inherited a set that was set up that way, and they fried. I actually attempted to repair them, they happened to be the very rate back contact type, but it was hopeless. They were totally ruined.