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The bifacial model presently available in PVsyst is based on a simplified 2-dimensional representation, with similar assumptions as the "unlimited sheds" or “unlimited Trackers” PVsyst simplified calculation. This approximate calculation may be extended to a 3D scene, provided that this 3D scene is sufficiently well represented by the "Unlimited sheds or trackers". You can read more about the bifacial model conditions in the following help page: https://www.pvsyst.com/help/project-design/bifacial-systems/2d-bifacial-model-conditions.html With multiple orientations and sub-systems with different table width, you can in version 8 create new "orientations" in the orientations window and group all the tables with similar characteristics in a sub-system/orientation, and apply the bifacial model to each sub-system in the system window

As you can see in the frames above what you have highlighted ("Number of rectangle-strings"), on your table there is a non-integer number of partitions. This means that either your tables are not consistent with the string length (can be an integer multiple or a simple fraction), or the length 31.75 is not exactly correct as a string length. The difference in length you are seeing is probably just the 0.54 and 0.34 remainder of the partitions that has shifted the partitions on the table. If your tables are just a multiple of a string length, the easiest is to use "Number of rectanlge-strings" on the tables to simply divide the string in the correct number of partitions.

Recently, we encountered a mountain-based PV project using bifacial modules with layouts involving multiple tilt angles and various azimuth orientations. When attempting to simulate this system in PVSYST, persistent errors occur. Could you clarify whether PVSYST currently supports simulating bifacial PV systems on complex terrain, particularly regarding the modeling of rear-side gain? If not, are there alternative solutions available? Thank you.

Hi, our team often get blank reports after we update to a new version. this does not go away on a restart and it happens to at least 4 users on our team. see below

Thanks! I used method 3, but there is an issue I explained in the picture below: although I have defined same rectangle sizes for rectangle string the final rectangles are not the same and I think it shouldn't be like that because 28 modules in series is valid for the whole scene.

I see ! I just remembered that in this version (7.2) there is a bug for trackers. In the object management window, the number of partitions is not affected to the right variable. It is connected to the size of the partitions instead which in turn makes it not work. Please use option 3 or update the PVsyst version.

You are right, it was a typo, my version 7.2. Do you have any idea why my shading scene in method one does not show proper shading animation? I don't even see the dotted lines that show partitioning is done, but the shading factor table looks good for a backtracking which is 0 everywhere. I afraid that it produces zero because shading is not working at all and not because of correct partitioning.

Hi, There is no object management window in PVsyst 6, so I assume you are using a more recent version. Which version are you using ? I have tried to see if solution 1 had a bug in version 8.0.19, but everything works fine. You are probably correct that solution 2 may have an issue sometimes. The zone tool is rather old and sometimes misbehaves. Solutions 1 and 3 should be equivalent.

PVsyst V6.2.16 I have a 2P project, half cell with 28 modules in series (string length). I can define partitioning in 3 different ways but the results of shading animation is not the same and also the iso diagram is not the same. I included the screen shots below for all there methods. Please advise on which method is the best method to use for partitioning.

Dear Jianguo Chen, Thank you for your feedback. I share your understanding : both dialogues, with those parameters, should lead to the same results. For me the correct plot is your top screenshot, from the menu "One shaded Module". I noted that this problem seems to happen only with "Twin-half-Cut" module: If I select a "In length" module, both dialoguess give me the same results I think therefore there is a problem with the calculation of the electrical layout in this specific dialog. I will create an issue to investigate it further and fix this problem in a future version.

For a TMEIC inverter we are using, the enhanced power you mention doesn't show up in the plot unless we check "Allows overpower." Is that usually the case?

In both versions an issue may happen for systems using the power shifting strategy with transformers losses. The issue happens when most of the PV production is diverted to the battery or most of the grid injection comes from the battery. In these cases the AC losses computation may lead to unrealistic values. This issue will be corrected in the next release. In the meantime, users are strongly advised to use PVsyst 8.0.17 for projects using power shifting.

Hello, You find a full explanation and a summery of common cases in the following PVsyst help page: https://www.pvsyst.com/help/project-design/shadings/electrical-shadings-module-strings/partition-in-strings-of-modules.html?h=partitio#up-to-748

Can anyone explain how to define the partitioning (nb. of rectangles in height and nb. of rectangles in width and also the height and width) if I have a 4 string tracker, 3 string tracker and 2 string tracker (Single axis E-W tracking) and modules in 1 portrait in a table? How will it change for landscape orientation or if I have 2 portrait orientation? How does it affect the shading scene?

Has this already been implemented?

I am not sure I understand your question. If you are looking for PVGIS 5.3 data using the SAHARA3 model, you can just download it from here: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html

No the tracker angles are the same. The interpolation profile is only a profile Shading factor = f(tracker angle). Therefore the only changes are in shading factors (for diffuse and albedo).

Dear Prof.André Mermoud： Recently, I have utilized PVsyst 8.0.19 for simulating the IV curves of BC modules under module-level and string-level shading scenarios. Given some inconsistencies identified in the string-level results, I wish to arrange a discussion with you on this matter. I increased the Arev factor of BC module to over 1000, and first simulated cell shading at the module level with 1 cell shaded. The results showed a 35% power reduction. When I used the string simulation tool to replicate the same number of shaded cells—i.e., a string configuration with one module per string and 1 cell shaded—the results displayed a significant discrepancy. Does it a bug? Does the Arev factor of BC modules fail to take effect at the string level? thanks! Best regards!

Thanks Michele, With different interpolation limits, would this mean that the tracker angles should be slightly different across the day, even at the same time stamp? The average tracker angles are the same across the middle of the day - is the difference being lost in a rounding error? Cheers

For a instalation i need to adapt my Weather data to PVGIS SARAH3: Sandia method last 10 years. i once dit it with PVGIS 5.2 sarah2 but idont find how to re create it?

Hello, You can find an article in our help that discuss the PR calculations: https://www.pvsyst.com/help/project-design/results/performance-ratio-pr.html?h=pr Kind regards

Hello, In the new version, an additional PR column was added for bifacial panels. My question is how the PR is calculated, and whether the simulation takes into account irradiation on both the front and rear sides of the panel. In addition, in your opinion, which PR value is the most accurate and correct one to use?

When creating your site, you can simply write or copy your values in the "Monthly weather data" tab

Hi the reason is in the calculation of diffuse and albedo shadings. For more information you can see here: https://www.pvsyst.com/help/project-design/shadings/calculation-and-model/diffuse-losses-with-tracking-systems.html This calculation creates an interpolation profile based on the available tracker positions. By changing the tracker limit, the support pointss of the interpolation profile are shifted, thus leading to (in principle slightly) different shading values.

I have monthly weather data for TMY data (Meteonorm 7.3). Could you please advise how to input this data into PVsyst and how to display it in the simulation report? The available data includes monthly ambient temperature and global horizontal irradiation, as shown below: Month Ambient Temperature (°C) Global Horizontal Irradiation (kWh/m²) January 7.5 92 February 8.8 106.5 March 12.7 159.7 April 16.6 187.7 May 21.2 230 June 24.5 242 July 26.8 245.3 August 26.2 225.1 September 23.5 182.9 October 20.5 144.6 November 13.7 104.7 December 9.5 87.2 Year 17.6 2007.7