How much extra output would a 200kW ballast mount system generate with a 10 degree tilt?

I have a 200kW flat roof, ballast-mount solar installation and I need to evaluate the cost-benefit analysis for using a 10-degree tilt versus a 5-degree tile (or even a 0-degree tilt).  How can I calculate the added output that my system would generate with an optimized tilt angle?  How would that benefit compare to the extra racking cost for going with a higher-degree tilt?


If you were in Phoenix, AZ, then you'd produce about 10 MWh more power per year with the 10 degree tilt. Not only that, but your system would stay cleaner at 10 degrees, than at 5 degrees. At 0 degrees, you'd have to do a lot of mopping to keep the system clean. I'm not sure what your actual latitude is, but you'd have to factor in your available roof space and inter-row spacing to get your extra racking costs. You can download an run NREL's SAM at with a variety of different racking angles to find out your best option. 


Send your location (address or lat / long) and I can tell you the best tilt angles (annual, adjustable for seasons), average solar insolation.
If you have shading data, I can include that too.
PS: This is not using SAM by NREL.