André Mermoud

Some people will perhaps like to have an average.

If this was the last error in PVsyst, we would be very happy. Would you be more rich when you get one Euro when your fortune is 449'000 euros ?

The only gains of yield in tracking systems are due to the plane orientation of course. These are correctly evaluated in the different tracking options of PVsyst. There isn't any reason that your PV module behaves differently in Tracking systems. This doesn't make sense to modify the PAN file parameters for such applications (nor for any other application).

Please read my previous post ! Here you have an inverter with VmppMin = 280V and VmppMax = 550V. And defined efficiency curves for 280, 480 and 600V !

This is not a bug. For normal sizing, PVsyst has opted for an hypothesis of limiting the overpower losses at 3%. However when you want to oversize the PV array, this limit is adjustable in the project's settings. See our FAQ Can I define a system with highly undersized inverter ?

In PVsyst you can define up to 8 different orientations. Some of your roofs with a same (or very simular) orientation may perhaps be grouped. Otherwise you should define several different variants, and add the results at the end.

In your first plot you have a "line of points" indicating that a string is not working. You should remove these points for the statistical evaluation. Now the scattering of the data may be due to a lot of different causes. The first one being the Measurement's quality (and especially the meteo).. You have several tools in the "Measured Data Analysis" for analyzing the discrepancies as function of different parameters, in relative or absolute values, as function of time, etc. This should allow to identify the phenomenons (or simulation parameters) causing these discrepancies.

This depends on the system you have defined of course. With tracking systems you will see the involved parameters. If you see "profile angle", you are probably in a sheds system.

Your explanations are correct. However the mismatch between the performances of each modules have nothing to do with the sahdings. For the mismatch due to modules: in the "Detailed parameters" dialog, please see the tool "Mismatch > Detailed computation". For the mismatch due to shadings, please see the graph in the "Module Layout" tool, page "Shading3D": press "calculate" and have a look on the I/V curves.

There may be several situations: - PVsyst doesn't treat hours with GlobInc < 10 W/m2 (remember that a very covered weather corresponds to 40-50 W/m2). - The inverter may be under its operating conditions. Please have a look on the inverter losses (IL_PMin, IL_VMin) for these particular hours.

The separators are not recognized. In EXCEL, you have a tool "Data > Convert" for importing data which are not recognized (select the whole column before using this tool).

You should choose the part which gives the higher losses in your system. By the way you can specify (add) an equivalent part corresponding to the other side if necessary.

This is not possible, and really not very common. We won't implement such a possibility in PVsyst. You should find another way of comparing your data (the total price instead of a specific one for example).

The help gives the list (and properties) of almost 20 popular data sources that you can directly import in PVsyst: See the help "Meteo Database > Notes on Meteo > Meteonote2_Meteorological data sources".

You can simply reinstall PVsyst. You should not "work" in the C:\program files\ area, which is pror^tected by Windows.

This percentage concerns the I/V curve calculation for one sub-module. It means that when 1 corner is shaded, 10% of the cells are shaded, 33% of the cells when 2 corners are shaded, etc. This affect the I/V shape of each shaded submodule. By the way this real shape has almost no impact on the full sub-array shaded I/V characteristics. Only the number of shaded sub-modules - whatever the number of cells shaded - is significant.

The calculation of the IAM loss on diffuse is based on the hypothesis that the Diffuse is isotropic. This means that the diffuse irradiance contribution is the same whatever the direction of the sky. Therefore we can calculate an integral of the IAM loss (function) over all the sky directions "seen" by the collector plane. This integral is independent on the sun position, as well as the goegraphic location. This is a constant value, only dependent on the system geometry.

There are 2 input current limitations in PVsyst: - At the sizing time: some manufacturers specify a maximum ISC current (or sometimes a maximum PV power) for the array to be connected on the inverter. To my understanding, this doesn't make much sense as the inverter is normally able to limit the input current (or power) by itself. The only cases where this should be respected are when this is a contractual condition, which affects the warranty. This will provide an error message, and the prohect cannot be created as such. - During operation, up to now there was a input parameter of the inverter "Minimum Voltage for getting Pnom". This corresponds indeed to an input current limiting, managed by the inverter. Since recent versions of PVsyst, this current limit may also be explicitly defined, alternatively to VminPnom. These 2 varialbes are closely related: Imax * VminPnom = Pnom !

If so this it is a bug. However there are so much possibilities with custom ASCII files... Please send us the original data file, the corresponding *.SIT file, as well as the *.MEF file you have used for this import. Please address them to support@pvsyst.com.

Yes, if you are using the tool "Databases > Import ASCII meteo data", you have the opportunity of importing Array temperatures in hourly values. And afterwards, to use these values during the simulation.

The clear day model is well established, and represents thre real data with an accuracy of 2 to 3% (depending on the Linke coefficient). If you have measured data far over these values (daily sums), either you are not using the correct solar geometry (the latitude or altitude is incorrect), or your data are not correct. I can't see any other possibility. This is physically impossible. NB: It is possible to measure temporarily high irradiances, up to 1300 or even 1500 W/m2 perpendicularly to the sun. This is due to a bright sun cumulated with a reflexion on a neighbour cloud. But these are transitory phenomenons, during some few seconds or minutes. Never a full day.

No sorry, we did not yet have time for developing this.

Importing "Plane of Array" (POA) data is not possible with daily values, because we don't have any model for creating a random distribution (synthetic hourly data model) from POA values. The error message is probably erroneous.

Yes, sorry. The import of ASCII measured data (for a system) don't work in the versions 6.60 to 6.68. This will be corrected in the version 6.69. NB: This concerns System data import (creation of *.DAM files). The import of Meteo data works correctly.

For the temperature evaluation at eac hour, PVsyst doesn't use EffArrC nor EffArrR, which are yearly averages, and for the whole system. It calculated a first evaluation of the Tarray with the STC efficiency. Then it recalculates the PV module output at Geff and evaluates the real efficiency at this temperature. Finally it will use this efficiency in the temperature evaluation (i.e: one iteration).