André Mermoud

See our FAQ Why sometimes the overload losses increases significantly without reasons ?

The shading calculation is a geometrical calculation as function of the sun's position. The program doesn't calculate the optimal distance between strings, as there is no optimal distance. This is a multi-variable and multi-criteria choice. It depends what you want to optimize. The warning you are talking about has nothing to do with these questions: after defining the 3D scene, PVsyst checks the compatibility between your specification of a number of modules (in the "System" part), and the area you have defined in the 3D scene. If you have defined a significantly too big area, or an insufficient area, PVsyst will warn you.

From version 6.60, the Degradation (year number for a simulation and degradation parameters) is indeed part of the parameters you can use/modify in the batchs.

The shading calculation is a geometrical calculation as function of the sun's position. The program doesn't calculate the optimal distance between strings, as there is no optimal distance. This is a multi-variable and multi-criteria choice. It depends what you want to optimize. The warning you are talking about has nothing to do with these questions: after defining the 3D scene, PVsyst checks the compatibility between your specification of a number of modules (in the "System" part), and the area you have defined in the 3D scene. If you have defined a significantly too big area, or an insufficient area, PVsyst will warn you.

Yes indeed, the irradiance on the PV module isw the GlobEff value. In the Help concerning the array temperature, this is a "simplification" just for explaining that this is the irradiance incident on the PV array, without referring to the details of the simulation (optical effects).

In PVsyst the cell's temperature is evaluated from the irradiance (and eventually the wind velocity) using a thermal balance, which is completely explained in the help "Project design > Array and system losses > Array Thermal losses". It involves namely a thermal loss factor U-value (expressed in W/m2K) which may be splitted into an constant Uc and a wind component Uv * wind velocity. The U-value should be adapted according to the installation conditions (free air circulation all around, or back insulated modules).

For a quick calculation, you can simply use "Unlimited Sheds" in the "orientation" part. Don't forget to define the electrical losses.

This is indeed on our ToDo list. But I don't know when this will be implemented.

Yes of course you can experiment all these features in PVsyst. For discovering the features of the software, you can download it from www.pvsyst.com, and use it with all its functionnalities during 30 days for evaluation.

Please see the FAQ Can I define a system with highly undersized inverter ?

There are almost 300 UPsolar modules in the database. I can't find any error in the number of cells. Please tell which module is in error.

To my knowing, this works quite well in the latest versions.

With Meteonorm within PVsyst, yu can get meteo data for anywhere on the earth. See our FAQ Which meteo data are available in PVsyst ?

For a Centrifugal pump, when specified as Head as function of Flowrate, PVsyst uses a model called "similarity laws" (see the help "Physical models used > Pump - Model description > Pump model from Head (and P) as f(FR), fixed U or speed". This definition also requires to know the efficiency (or Power) as function of the flowrate. For all other input parameter configurations, PVsyst doesn't use any model. It determines any operating conditions (I, U, H, F) or (P, H, F) by an interpolation between the specified operating conditions. This may represent a rather complex calculation. See the help "Physical models used > Pump - Model description". You have a detailed description of the pump model in a document available on our web site: "Technico-economical Optimization of Photovoltaic Pumping Systems Pedagogic and Simulation Tool Implementation in the PVsyst Software", André Mermoud, 2006 Research report of the Institute for Environmental Sciences, University of Geneva.

The transposition models take indeed the albedo of the terrain in front of the plane into account. If you have snow, you can increase the albedo factor (monthly values) in the Project's definition.

Yes, the light-soaking gain of CIS modules take place progressively with the sun irradiance, and becomes fully effective after some accumulated dozens or hundreds of kWh/m2. But sorry, the manufacturers don't give more information about this time.

Portrait, landscape and U-configuration are taken into account with the "Module layout" detailed calculation, applied to each module in the array. You can have a look on the "pedagogic" I/V curves shown with this tool (button "Calculate > page I/V curves").

As we cannot control the contents, we don't distribute any training certificates to third-party training organizations.

The ambient temperature may indeed be lower on the water surface. However I don't know any study evaluating this effect. Now for the albedo, if you have rows (sheds) arrangement only the first row will "see" the albedo. For all other rows, the water surface is not visible. Therefore there is a shading factor of (n -1)/n on the albedo factor (n = number of sheds, illimited sheds hypothesis). By the way, however surprising it can appear, the albedo contribution of a lake (during the full year) has been measured as very low (much lower than the 0.2 usual coefficient).

The main simulation variables are explained in the help "Project design > Results". However this may not be completely up to date, we may have added variables which are not listed.

I can't explain how you can get a positive value (gain) for the overpower loss. If so, please send your whole project to support@pvsyst.com, using "Files > Export projects" in the main menu.

At first sight ... When cells are shaded in one only sub-string, the module current will be limited to half the normal current. As soon as cells are shaded in both sub-strings of one submodule, the submodule will behave in the normal way. NB: we don't intend to implement such a specific case in PVsyst, unles this becomes a general layout adopted by a signigicant number of manufacturers.

There is indeed an error in versions 4.46 to 6.52: when defining a not-south azimuth for the Single axis tracking object in the 3D scene, this is not taken into account in the simulation. This was corrected in the V 6.53.

0.041667 = 1/24. This constant means one hour in units of days.

The calculation is done for the hourly step. If the sun is apparent during 20 minutes, and below the horizon during 40 minutes (theoretical sun position), then the simulation will account for 1/3 of the beam component for this hour.