André Mermoud

This means that you have defined efficiency curves for 3 different input voltages (see the "Efficiency curves" page). But these input voltages are not well defined (they should lie between the Minimum and Maximum MPPT voltages, i.e betqween 888 and 1275 V in your case).

You can manage the IAM parameters in "Detailed Losses > IAM". You can change the bo factor, or define a customized IAM profile. Here you have also a detailed tool for the analysis and comprehension of this IAM loss. But sorry, we don't have reliable information about one or another product.

Yes in the present time the tree are considered as absolutely opaque. It would be very complex to define a semi-opaque shading in our calculation framework. And moreover changing along the year ...

The PHOTON database is indeed no more available. They have changed their site and the Database page is not accessible. However we are not managing this tool in any way. Nevertheless you can easily create your own components by yourself. The easiest way is to choose a similar existing device in the database, modify its parameters according to the manufacturer's datasheets, and save it under a new name, therefore creating a new file in your database. For Crystalline modules, except Isc, Vco, Impp and Vmpp, nb of cells in series and module sizes, you can let all the other parameters at their default value.

You should ask our administration admin@pvsyst.com.

In the "Orientation" part, you have to specify 2 orientations. And in the 3D shading scene, you can: - either define 2 array of sheds, and place them Back-to-back, - or since version 6.42, you can directly choose the object "Domes".

Thank you. It is indeed a mistake in this text, we will correct it.

For the initial year specification when importing ASCII data, I don't know. At first sight we didn't modify anything here. We will check. For the list of modification, it is indeed in the release notes when you download the new version. You can get all modifications in the "Readme.TXT" file, or on our web site, menu "Software > Software developments".

The "Active area" is the PV modules area. In PVsyst, it is the area of one module (LengthxWidth) times the number of modules. The "Ground area" is the area occupied by the PV array (not strictly well defined). The usual definition of the GCR (Ground Coverage Ratio) is the ratio of the Active area to the Ground area.

Defining each table-module as one "rectangle" is the correct way. If the tables are subject to shades from surrounding (not-regular), this will under-evaluate the real electrical shading losses. If the modules are in shed-like arrangement (regular shadings on each row), and you have more than one string per inverter input, this way will give correct results. Indeed, as as soon as 1/3 of the sub-modules are shaded in a string, the string will be completely inactive (for beam component). See the explanation on How to evaluate the effect of by-pass diodes in shaded arrays?

There was indeed a problem when manually defining the monthly values of a site. This has been corrected in the version 6.43.

This arises sometimes (rarely), but this doesn't prevent working with the 3D editor... This editor will be completely renewed in a next version.

The shading factor is the ratio of the shaded area, with respect to the full sensitive area. Therefore it is 0 when ther is no shading. Please tell me on which page of the tutorial the shading factor is one for no shadings. I checked and didn't see anything like that. (NB: This was the case in very old versions of PVsyst (perhap's in versions <=4, I don't remember). In the shading factor table, the height is defined as the angle between the concerned direction and the horizontal plane.

PVsyst only treats the mix of 2 orientations on a given MPPT input. If you have 3 orientations, you should define an average between two of them. The results will not be very different.

The parameters (tilt, azimuth) should match between the "Orientation" part and the 3D shading scene of course. Wanting to do otherwise doesn't make sense.

If you read the instructions on the dialog in "Preferences", you will read this: "This choice is for use outside of a project (tools, database and new projects). The model choice for actual simulations is now defined in the project's parameters". The project's parameters are defined under the button "Albedo & Settings" in the Project's dialog. Sometimes reading the instructions in PVsyst may avoid loosing time...

This publication is named "Measuring and Modelling Nominal Operating Cell Temperature (NOCT)" Matthew Muller, NREL, Sept 22-23, 2010. It is part of the presentations at a Workshop dealing with PV performance and Modelling, held at Sandia Laboratories (Albuquerque) in May 2010. I don't know if it is publicly available.

This depends on your maximum backtracking angle (depending on the pitch and tracker's width). If this angle is between 45° and 55°, the limit of 45° will arise before the backtracking limit.

The backtracking calculation is made analytically. It is a very complex calculation, I have not established the algorithms for special cases like tiltd slope between trackers. The only way for doing this in full generality would be to use a successive approximation process at each hour. Now if you have an irregular altitude distribution (for example on a hill), the backtracking has to be computed according to the "worst case" tracker's pair configuration. It cannot be optimal for the full array. If you want a "real" backtracking for the full array, you have to compute the orientation of each pair of trackers independently.

This is a difficult question. For Africa and Europe, the PVGIS data are rather good for recent climate. For the USA, there are several sources, I don't know which is the more reliable. For the rest of the world, if you have doubts, you can also buy paid data.

When creating a synthetic hourly data file (from external monthly data), PVsyst uses the algorithm which is included in the Meteonorm program (DLL used in PVsyst). During this process, the program Meteonorm establishes the Diffuse component (from global) using the Perez-Ineichen model (also named DirInt). Now if you specify Monthly values for the diffuse, PVsyst will renormalize the Diffuse computed from the model, in order to get the exact specified Monthly sum.

Your project file (and probably the associated calculation verions) is corrupted. This usually arises when you try to read a file which has been elaborated from a more recent version of PVsyst. In this case you have to remove the corrupted files from your workspace.

The site of the projects should contain Valid Monthly meteo data. Thes data will not be used in the simulation, but are involved in several sizing tools. If your imported data are not complete (as it is your case), you should define valid and complete monthly data, what you can import for example from Meteonorm.

The shading factor is the ratio of the shaded area, with respect to the total sensitive area. For a same collector tilt, if the pitch increases, the mutual shadings (shading factor) will decrease of course. I don't understand the rest of the question. In the 3D construction, you can have a look on the shading factor using the "Animation" (button on bottom left).

The number of MPPT's is a physical feature of each inverter. In PVsyst, you normally use the MPPT features of the inverter. But in a pre-study, you have the opportunity to get rid of this and consider the inverter "as a whole", i.e. one MPPT input (option "Uses MPPT" unchecked). Now in one sub-array, you have to specify the number of strings, and the number of MPPT inputs used for this sub-array. For example if you have 8 strings, you can distribute them on 4 MPPT inputs. If the inverters have 1 MPPT, this will mean 4 inverters; with 2 MPPT per inverter: 2 full inverters; with 3 MPPT per inverter, 1 inverter and a third. You can use other MPPT inputs in other sub-arrays.