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André Mermoud

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Everything posted by André Mermoud

  1. There are indeed two MPP maxima. Here an operating point at the minimum voltage, the other one at secondary MPP. This could also be 2 different MPP in the allowed Voltage range. In these situations, the behaviour of the real inverter is not clearly determined. Sometimes it can stay "blocked" on the lower maximum. The PVsyst simulation always chooses the higher Pmpp available; this may be slightly optimistic. But the difference is usally extremely low over the year.
  2. The grid limitation is meant for big systems. Defining a value less than 1 kW doesn't make sense in practice. For the unavailability of the "Simulation" button when the message sais "Ready for simulation", it is indeed not normal. However this only arises when you define a grid limitation, and the Grid limit power is set to 0. We will correct this in a next version.
  3. These values in the hidden parameters ("Low/High Grid Power limitation Power Ratio") are only used for the verification of your definitions (warning messages). The PNom ratio mentioned on the dialog is the ratio of your grid limitation specification, and the PV installed power. It is shown just for information.
  4. The C1, C2, C05 values are battery definition parameters. These have nothing to do with the results you are waiting for. Here you have defined a charging power of 6.25 MW, for a battery pack of 27 MWh. This will indeed fill the batterty pack in about 4 hours if the PV system provides a sufficient Power for that. Which will probably be the case rather early in the morning, since your PV systerm has a nominal power of 52 MWp, i.e. almost 8 times the charging power !
  5. The C10 is the basic definition of a battery in PVsyst. This reference cannot be changed. You can have the correspondance with other Cxx values in the battery definition dialog: here a battery defined with a C2 capacity of 105 Ah will have an effective C10 capacity of 108.4 Ah. This is the value defining this battery within PVsyst. Now when using it, the simulation will permanently re-evaluate the capacity as a function of the Charging/Discharging rate along the simulation.
  6. With this configuration, the choice of grouping your strings on two MPPTs is not equivalent concerning the electrical shadings. The only way to evaluate this is to perform the simulation with different attributions. The electrical shadings loss (according to module layout) may be different. The differences will probably be very small (depending on your shading environment).
  7. The irradiance on the tilted plane is computed using the transposition model (Hay or Perez), as described in the help. This strongly depends on the beam component (i.e. the diffuse). Now when the GlobHor is modified, usually the diffuse is also affected (a higher GlobHor means a higher beam, therefore o lower diffuse fraction). This will affect the ration GlobInc/GlobHor.
  8. The shadings calculation "According to strings" is applied to an array connected to one MPPT. With optimizers, the MPPT input is one (or possibly 2) modules. Therefore each rectangle should represent the set of modules connected to one optimizer. NB: The ModuleLayout option is also useable for the calculation of the electrical shading loss with optimizers.
  9. There is no way in the present time for explicitly defining the tracker's position. Providing such a possibility (i.e. defining the tracker's position by an external file) is on our roadmap, but will not be realized before several months.
  10. The simulation works exacly in this way: the individual inverter limitations are applied first. And if the grid limit imposes an additional restriction, it will be accounted as "Unused loss" in the loss diagram (provided that you have specified "Accounted as separated loss" in the grid limiting dialog). If you uncheck "Accounted as separated loss", all the losses will be accounted as inverter losses.
  11. Yes, these are two different bugs. We will correct this for a next version, but I don't know when. NB: There is indeed no way of modifying the number of cycles within PVsyst in th present time. The only possibility is to directly edit the *.BTR file, for example in Notepad, and modify the parameters at the end of the file:
  12. Yes indeed. providing an hourly definition of the Grid limitation is on our roadmap. However I don't know when we will be able to develop this feature.
  13. This doesn't make much sense. The voltage mentioned here is a limit for operating conditions. The current is roughly proportional to the irradiance. The input current limit has not a "universal" definition, especially at the array level. It is not always well defined in the OND files.
  14. As it is implicitly involved in the post of DTarin, in the present time the AC losses (Line + transformers) don't take the impedance into account; the calculation is purely resistive. Implementing the lines impedances is on our roadmap, but we don't know when we will do that.
  15. I don't know. To our knowing, the "Peak shaving" feature works quite well. Please send your whole project to support@PVsyst.com, using "Files > Export projects" in the main menu, in order that we can analyse your problem.
  16. The Perez model calculation has not been changed. It is well-known that the Perez model has a higher gain that the Hay model. For fixed planes the difference may be of the order of 1%, depending on the tilt of course. Here you have probably a tracking system, perhaps with backtracking. This difference of 1.6% seems indeed high, but is probably reasonable. Please check that all other parameters of your simulation are quite identical.
  17. Basically, in the present time, PVsyst works in hourly steps. Therefore this is not possible. By the way, providing 10 min output data would require to avail of 10-minutes meteo data (irradiance and temperature).
  18. The classes are indeed of 50 kW (this is mentioned on the axis ... since the version 7.2.18! ). Now I don't have any explanation to this variability, this is a statistical variability.
  19. You should indeed simply redefine a HV transformer rescaled according to the nominal power for each system. For your system of 1/6 of the full power, you will simply take 1/6 of all Powers specified for this transformet (nominal, losses)
  20. This error has been very probably corrected in the latest versions, please update.
  21. Yes of course. Any inverter or PV module may be used in building installations, without restriction. Obviously some models are more specifically suited for this use (for example modules for façades, waterproof roofs, or semi-transparent), some inverters with storage management, etc). Many of these components may be present in the PVsyst database. But sorry, there is no filter for identifying them according to their specificities.
  22. I don't know. We don't use Helioscope. However to locate the problem, you should probably compare the results at different stages of the simulation: Meteo data inoput and Irradiance on the PV modules, shading losses, output of the PV array, output of the inverter, AC losses, etc. I don't remember any recent complaints from users about such comparisons and differences.
  23. Remember that the "Additional data => Measured data" page is a tool for analyzing the low-light data, usually recorded according to the IEC61853 norm. This tool allows to import measured data, but it is completely independent of the "edited" PV module. After importing, you can play with the parameters for adjusting at best the model to the measured data. When exiting this tool you can ask for adjusting the parameters of the "father" PV module, in order to get the same low-light behaviour at 25°C that you have chosen. This will not necessarily result in the same Rserie, as the STC values of the "father" model are not necessarily identical to the values measured at 1000 W/m2 and 25°C. In your case the Rserie is indeed identical (0.186 ohm). However the parameters chosen for the "measured" module are not saved on the file. When you reread the module, the Rserie/Rshunt values are set to an initial value defined by PVsyst (i.e. default rel. efficiency@200W/m2 = -3%). You can observe that on the second image, the mention "RSerie optimized" appears, when it is not present on the last image.
  24. Yes, this is a problem that we are studying. This will probably be improved in the next version 7.3.
  25. This bug has been fixed in the version 7.2.19. The value "produced energy" is not correct, the results E_Solar + E_Grid at the bottom of the loss diagram, or on the monthly "main" results, is the correct value. The error is 0.62%. This affect the PR shown on the Main results.
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