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Hello, solarguru Thanks for your comment, I will try to draw 3D shading scene to check out backtracking issue again. Have a good day!

Hello, solarguru 2. Doubt here. What would be the major difference between "Horiz. axis, unlimited trackers" vs "Tracking tilted or horiz. N-S axis" when using bifacial modules? (I already posted one question in the forum today). When to use each filed type for simulation? I've always used "Unlimited" one in fix and tracker when doing bifacial simulation without being critically considering the difference and now I would like to fully understand about it. Could you explain to me, please? 3. You are right, I totally got mistaken the way of calculation of loss. Thanks for your great help, it actually help a lot to improve my usage of PVsyst. Have a great day!

Hello guys, I find it a bit confusing when in comes to selecting "Field type" in "Orientation" box especially about the notion of "unlimited ~" In PVsyst help, the following explanation presents: (http://files.pvsyst.com/help/orientation.htm) Unlimited sheds: To be used when the sheds are very long with respect to their width. If the sheds are too short as one cannot neglect the edge effects, you should define sheds in the "Near shadings" CAO option instead. And, "Horiz. axis, unlimited trackers" is not explained in this chapter. Here are my questions: 1. How "unlimited sheds" in fixed and "Horiz. axis, unlimited trackers" hold the sun position? As an example, how am I supposed to know the rod of the tracker is aligned to N-S direction or W-S direction in "Horiz. axis, unlimite trackers" ? how to vary the simulation between the rod aligned to N-S or W-S using in "Horiz. axis, unlimited trackers"? 2. I tried to google and could not find the definition of "the edge effect" indicated above "Unlimited sheds". I just saw "cloudy edge effect" but it seems that the edge effect input by PVsyst sounds different. What is the meaning of "edge effect" in PVsyst simulation? 3. What would be the major difference the selection of "Horiz. axis, unlimited trackers" vs "Tracking tilted or horiz. N-S axis"? What I mean, which case would be the exact case of using each "Field type"? What I found is that it only difference comes from "the edge effect" seemingly. Thanks in advance,

Hello, Solarguru 1. What you meant by "~6%"corresponds to "Near shadings: irradiance loss", didn't you? What I found out a reply from PVsyst team regarding "Near shadings:irradiance loss" is the following: "The shading is accounted for the beam component (the shade what you see), but also on the diffuse and albedo components, which are integrals of the shading factor over all the directions "seen"by the PV module." So to clarify, with backtracking can decrease "Near shading:irradiance loss" and do not cause "Shadings: electrical loss". Is it reasonable think in this way? 2. Taking into account your suggestion, the selection of "using the 3D scene for calculations" - which I should turn on "Near Shadings" in "Optional tab", the PVsyst doesn't allow me to construct 3D scene with "Horiz. axis, unlimited sheds." in "Field type" in "Orientation"box. The thing is that I am doing a simulation with bifacial case then I cannot use another "Field Type" such as "Tracking horizontal axis E-W"and "Tracking tilted or horiz. N-S axis" which ALLOW me to construct 3D scene in "Near shadings" box. Can I ask you how and what setup you used to do a bifacial simulation with 3D shade scene? 3. I, manually, calculated the loss with your waterfall.Simply from "455193 MWh"(Backtracking, at the second stage of waterfall), total loss turn out -20.8% (-0.1-6.6+0.4-1.5-1.2-0.4-1.5-2.3-7.6 = -20.8). 455193 * (1-0.208) = 360512 MWh which is not equal to "366997 MWh" indicated value. Why does it happen like this? Thanks for your help, solarguru

Hello, Solarguru In the "Orientation" menu, I selected "Horiz. axis unlimited trackers" in "Field type". Due to this, I cannot opt for neither "Linear shading" nor "According to module strings" in "Near shadings" box. (As soon as I draw a construction in "Construction/Perspective", it changes the orientation setup in "Field type" automatically.) And I assume that the electrical loss get influenced only by "backtracking" option in my case since I did not change nothing but "backtracking" in orientation tab. I understood "It should be noted that the Backtracking doesn't increase the total irradiance received." can be translated into "Backtracking reduces POA" confirmed by the simulation report. Any suggestion to correct the shading setup in my simulation? ("Horiz. axis unlimited trackers"). The GCR value applied to all the reports was 41.7%. I tested the annual energy yield comparsions by the following and found out some interesting arguments: Unit: MWh/yr GCR /without backtracking/ with backtracking/ Diff. Mono 83,30%/ 29,6 / 29,5 / 0,1 41,70%/ 34,8 / 34,6 / 0,2 20,80%/ 36,3 / 36,4 / -0,1 13,90% /36,8 / 36,9 / -0,1 Bifacial 83,30%/ 34,5 / 32,2 / 2,3 41,70%/ 38 / 37,1 / 0,9 20,80%/ 39,2 / 38,9 / 0,3 13,90%/ 39,5 / 39,4 / 0,1 By this result, backtracking application depends on at least GCR and geo-dependent climate whether apply or not. In my case, bifacial with backtracking wouldn't be effective as other places, would it? And regarding to the location-dependency, I will check out further. Thanks for your help, Solarguru

Hello, guys I would like to ask you why backtracking give less yield than the one without backtracking in the simulation report of PVsyst 6.7.8. I selected "no shadings" in "Near shadings" box in "Optional" part. See below the attached pictures. My question are below with bold characters. [Monofacial case. Left:without backtracking / right: with backtracking] [bifacial case. Left:without backtracking / right: with backtracking] Some doubts cased by the statements below: 1. In PVsyst help says "It should be noted that the Backtracking doesn't increase the total irradiance received. It only improves the electrical loss effects of the shadings." -> But, the report (the pictures attached) say the opposite: the system without backtracking has higher "Global incident on collection plane". Am I mistaken some part here? 2. Backtracking's advantage "Though the angle of the panels is not optimal, the loss from the off-angle is typically less than the loss that would result from shading the panels, added John Williamson, director of engineering at Array Technologies." Link: https://www.solarpowerworldonline.com/2015/07/how-does-solar-backtracking-make-projects-more-productive/ -> "Global incident collector plane" is higher w/o backtracking. Although, it has higher shadings loss such as "irradiance loss" and "electrical loss" compared to the one with backtracking, total energy yield present that the backtracking system is not effective strategy to improve the energy yield. Is it reasonable conclusion according to the simulation report? Am I missing something here? Simply, I cannot understand why it happen like this. Could anyone can guide me to figure out this phenomenon, please? Thanks in advance

Agree with you. One doubt, What is the way to ask some topic or request directly to PVsyst team? since I am a new in PVsyst forum, I do not know how to approach to them. I saw some topics replied by PVsyst team while, other are not replied by PVsyst team. This cause me to have this doubt. Thanks Solarguru and have a good day!

Hello, Solarguru Thanks for your info. Accordingly, monofacial + backtraking: select backtracking only in orientation tab bifacial + backtracking: select backtracking both in orientation tab and in bifacial tab Then, backtracking selected only in bifacial tab would not any make sense. is it reasonable to think in this way?

Hello, guys I have a doubt on backtracking in PVsyst 6.7.8 The configuration I am using is below (bifacial + tracking system with backtracking) Input parameters - Main parameters - Orientation - Field type - Horiz. axis, unlimited trackers + backtracking selected Input parameters - Main parameters - System - Select the PV module - bifacial system - Unlimited Tracker 2D model - Orientation parameters - Uses backtracking selected I find it confusing what different between two options of backtracking. It is observed that both selected, either of two backtracking options selected, none of them selected give me different result. Could anyone give me an clear explanation of it, please? Thanks,