Tracker vs fixed tilt systems in 3D scenes

[laurahin]

Hi,

Questions about 3D scenes seem to come up in multiple places in the forum, so I will ask a summary question here:

       Is it true that PVsyst's ability to handle 3D scenes is different for fixed tilt and tracker systems?

My understanding has been that PVsyst can only handle a limited number (8) of fixed tilt orientations in a single scene and that bifacial modeling cannot be included in this case, but we have had no problem treating PVcase scenes with 3D terrain and trackers, whether we use bifacial modules or not.  

We assume that the difference is caused by the potentially infinite number of "compound angles" produced when the terrain skews fixed tilt racking because PVsyst cannot model this many different geometries in a single scene.  

Thanks,

Laura

 

[dtarin]

I would answer yes to your question but with some fine print. For FT as you say, PVsyst can be set to use different averaging intervals to arrive at up to 8 distinct orientations for monofacial simulations. Maybe this could be lifted since we can have unlimited sub-arrays now? For bifacial systems, a single orientation is needed. This is true for both FT and SAT; however, SAT doesnt have the same checks that FT does. Placing two tracker arrays at different azimuths does not activate any errors when it should. 

When placing trackers on terrain, the Z coordinate does not matter for bifacial. The tilt is calculated as an average automatically, and trackers are placed at the same azimuth. If you place trackers at a different azimuth, the software will not detect and it will select the last change detected (or something to that effect). There are some things you can do to have PVsyst detect the orientation is incorrect, but it will always just select one of the arrays and then let you proceed, which that in itself is also incorrect. I have not tried multiple azimuth tracker systems from PVcase, though, so not sure how PVsyst handles it. We dont see those in designs though so probably not worth looking into. 

In any case, the different with SAT is that 1) tilt is calculated automatically as an average 2) they're always at the same azimuth, so bifacial has no problems. There is a single orientation used for the calculations. With FT and terrain, you can use bifacial, but you must average it out to a single orientation.