From my perspective, I would like to have confidence that pitch is maintained between rows as I adjust the ground slope. During construction, rows will be installed with the specified spacing, as measured over the ground regardless of slope.
From a little playing around in PVSyst (v6.48), it appears that the shed-to-shed slope method DOES maintain pitch
However, if you use the Ground object and Zone method, be sure to define the pitch as 'cosine(slope angle)'. It seems that this may be because the Zone is defined and filled out in the x-y plane, so the pitch value that you enter to fill out the zone is actually the projection
of the sloped pitch onto the x-y plane.
See attached images.
In my exercise, I created a ground object with coordinates (0,0,0), (0,20,0), (20,0,20), (20,20,20) (a -45 deg slope), and used the Fill Zone tool to create a field of 2 tables.
Next, I created a PV shed object, defined a -45 deg shed-to-shed slope, and positioned it on top of the tables in the ground zone.
PV modules for both the ground zone tables and the sheds have the same length-width dimensions and the same plane tilt.
Image 1: x-y view of the shed (pink) and zone tables (blue), with the measuring tool showing 10.0m between zone tables in the x-y plane.
Image 2: x-z view of the shed (pink) and zone tables (blue), with the measuring tool showing 14.15m between zone tables along the ground plane. cos^-1(10/14.15) = 45 deg
Image 3: x-z view of the shed (pink) and zone tables with new pitch defined as 10*cos(45 deg) = 7.07m (blue), with measuring tool showing 10.0m between BOTH sheds and zone tables.
Maybe this is obvious to everyone, but it took me a test simulation to figure it out.