André Mermoud

The problem is perhaps what you are expecting... If the yield is higher, this doesn't mean that the PR is higher, as it is normalized to the installed PNom. If the PV modules have rigorously identical performances (same Low-light behavior, same temperature coefficient, same IAM), the PR should be identical. Now you don't tell us which level of differences you observe (in percentage). There may be a discrepancy: - If you have inverter overload: in this case the loss will be higher for the second system, and therefore the PR will be lower. - As explained in the FAQ Why is the Pmpp of my modules different from the specified value?, the Imp*Vmp at STC may be different from the PNom of the module. This will induce a distortion of the PR.

You can modify this limit in the Hidden parameters, topic "Miscellaneous: Meteo, Simulation, ... ", item "Minimun power for Module Layout Error" (almost at the end of the topic).

This is a worst case choice. Please carefully read the FAQ post How to adjust the design temperatures ?

Defining a Bi-facial module is obviously not sufficient. When you choose a bifacial module, in the "System" dialog you have a button "Bifacia system" for defining the full Bi-facial configuration. NB: The bi-facial option is only available with Grid-connected systems in the present time-.

I don't know what you are talking about. There are no attachments.

This path is the storage area of the program. PVsyst cannot write anything in this location, protected by Windows. You data are stored in your own workspace, located at C:\ Users \ YourSession \ PVsyst660_Data \ Now you can also use the tool "Files / Export components" in the main menu of PVsyst for directly export your files.

I don't know. Nobody has never reported such a problem. The export of projects works quite well, using "Files > Export projects" in the main menu. Please contact support@pvsyst.com and explain exactly what you are doing.

You cannot export Meteonorm data. Meteonorm is also a software, sold as such. By contract with the Meteonorm team, the use of the Meteonorm data implemented in PVsyst is reserved to the internal use within PVsyst. If you need data for other uses you should buy the Meteonorm software.

There is no specified limit here. The Temperature loss is related to the muPmpp temperature coefficient of your modules, and the array temperature TArray. It is evaluated using the one-diode model and the thermal model described in the help "Project design > Array and system losses > Array Thermal losses"

A monthly clearness index of 0.85 is considered as irrealistic by PVsyst. The limit is fixed to 0.82, however you can change it in the "Hidden parameters", topic "Miscellaneous: Meteo, Simulation,...". Now I have just tried to define the GlobHor in Kt units, and this works quite well: you can save your SIT file with these values. NB: In the "Import Meteo data" section, you have the opportunity of creating a file of all Clear days for any location.

You cannot export Meteonorm data. Meteonorm is also a software, sold as such. By contract with the Meteonorm team, the use of the Meteonorm data implemented in PVsyst is reserved to the internal use within PVsyst. If you need data for other uses you should buy the Meteonorm software.

In previous versions, it was possible to activate the backtracking even without defining the 3D scene, which lead to neglecting the mjutual shadin losses on diffuse. Now you have to define the system in the 3D scene. The pitch is specified in this 3D scene.

There is indeed a little limitation/error in the model of PVsyst. When the diode Saturation current goes below 0.02 pA, it is limited to this very low value, for numerical reasons in the model calculation. This may arise with modules of high serie resistance (close to the RSerei limit), i.e. low diode ideality factors (<0.95). It appears with very low temperatures (< -10°C). This inverses the muVoc coefficient below a limit temperature, ,but has a very low effect on the model results.

Basically the TArray corresponds to the cell temperature. If some people make a difference between Cell and Module temperature, this is mainly related to the way of measuring it. Please remember that a thermometer always measures its own temperature. If you put a sensor behind the PV module without insulating it, there will be a thermal flux between the cell temperature and the sensor, and from the sensor to the ambient, so that the sensor measures an intermediate value (not well determined). If you put some insulation, you block this flux and the sensor will measure the "real" cell's temperature (thermal equillibrium conditions). For such a measurement, after some optimizations at the University of Geneva (using a special module with an integrated sensor directly on the cell within the encapsulation), we propose to cover the sensor with a piece of polystyrene of about 7 x 7 x 1 cm3. This size ensures a compromize, i.e. a sufficient insulation, without perturbating too much the local Cell's temperature.

The definition of the SOC (State of Charge) is 0 for a completely empty battery, and 1 (100%) for a fully charged battery. A SOC of 50% means a half-charged battery.

In your comparison, the second option certainly gives a higher yield (E_Grid). Please check. However if you have identical PV model behaviors, the PR should be identical, as you have different Nominal powers, compensated by different efficiencies. Except if you have overload losses. In this case, you will have higher overload losses with the second option, and therefore lower PR. NB: Please remember that the PR doesn't depend on the Efficiency. A higher efficiency means a lower area for the same nominal STC power, and therefore a lower Gincid. This result may be biased: - If the low-light performance of both modules is not identical (essentially depending on Rserie) - If the PNom of both modules (370 and 365) are not rigourously equal to the Imp * Vmp product at STC. Please see the FAQ Why is the Pmpp of my module different of the specified value ?

We update the database using the requests of the manufacturers, and publish it with each new issue of PVsyst. We can't of course follow all the new products of all manufacturers. It would be a very big task, and we don't want to include data without the acknowledgement of the manufacturer. Therefore, please ask your provider/manufacturer to take contact with us for updating the database. The database of PVsyst holds now about 15'000 PV modules and 5'000 inverters. 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 (mainly Rserie, Rshunt, Rsh(0) and RshExp) at their default value. You have a checkbox near to each parameter for retrieving the values proposed by PVsyst.

In PVsyst the Voc(temp) is calculated by the one-diode model. The expression given here is a direct result of the "pure" one-diode model: you can easily get it by simply writing the one-diode model equation for I = 0 PVsyst adds some corrections to this "pure" model, so that the result may be slightly different.

Before defining the Bi-facial tool, please make sure that your system is really compatible with a tracking array, horizontal axis orientated at -9°: - In the orientation part "Horizontal axis, unlimited trackers", or: - In the orientation part "Tracking, tilted or horizontal axis", - And in the 3D part you have to define an array with Azimuth = 0 in the tracking parameters, and rotate this whole "rectangular" object by -9° in the scene.

This information is now part of the project: in the project's definition dialog, button "Project's settings". The value in the hidden parameters is just an initialization for new projects.

The agreement between the simulated data and measured ones highly depends on the meteo data. And as a second cause, on the parameters you have chosen for the simulation. They may also be due to an erroneous measurement. In good measurements and simulation conditions, the accuracy of the simulation is usually below some few percents. Please see the FAQ What is the accuracy of the simulation results ?

You can simply save the whole workspace \PVsyst660_Data\. You will find its location in the main menu "Files > Workspace" dialog. NB: Remember that at each new installation (update), PVsyst automatically saves a full copy of your present workspace.

Please send the following files to support@pvsyst.com: - your original data CSV file, - the *.SIT file of the location of your data (that you are using for the import), in the directory \sit\ - the MEF file (formatting file) you have defined for this import, that you will find in the directory \Meteo\ - the MET file you have created.

When you open the dialog "Import ASCII Meteo files", in the first frame "Ascii Source file", make sure that you have correctly defined the site of your data.

Yes, when you have a tilted base on your PV tables, the plane orientation changes (tilt and awimuth). See our FAQ With sheds on a tilted roof, PVsyst changes my orientation.