Dear Fred,
Are you asking how to determine the maximum number of panels that avoids self-shading for an array with one-axis tracking in SAM, or for a general equation that you can use outside of SAM?
In SAM, you can use the "Self-shaded" mode with one-axis tracking (on the PV Subarrays page), and adjust the ground coverage ratio for the area you have available for the array. Then you can adjust the number of modules (and inverter) on the Array page until you have a system with the cost and generation profile you want. The process in SAM is iterative: You can systematically try different layout options. In SAM, you can see the effect of array layout on self-shading and DC voltages and power at the inverter input to help you choose the best design for your application. See the help topic for the PV Subarrays page, particularly the section on Shading for one-axis trackers and ground coverage ratio for more details: [url=http://file:///C:/SAM/2014.1.14/exelib/help/html/index.html?pvfp_subarrays.htm t=_self]SAM Help - PV Subarrays[/url].
Note that in SAM the packing factor input is only used to calculate the number of acres for land cost calculations. The packing factor input is independent of the ground coverage ratio even though in an actual system the two values would be related.
Best regards,
Paul.
