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PVSyst & PVSol Discrepancy


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Hello Support, 

I have created a design on a site with the same system size on PVSol & PVSyst but it gives me the difference of  50kWhrs/kWp/year. As per my understanding, in PVSyst there is much more flexibility as compared to PVSol of the loss consideration and they are set up differently in both software so it's obvious the result will come differently. 

How I can consider the following losses in PVSol in order to get the same results?

- LID - Light-Induced Degradation
- Module Quality Loss
- Thermal Loss factor
- Module mismatch losses
- Strings Mismatch loss
- IAM loss factor

Looking forward for your response. 


Kind Regards,

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  • 1 month later...

Dear OAM,

sorry for the late reply, your question must have slipped through. In fact, there are a lot of differences between PV*SOL and PVsyst, a lot more than you mentioned. The most important probably being the climate data used and the models to calculate the irradiance on the tilted plane, especially if you have a 3D environment with shadows. Also the time step causes huge differences - in PV*SOL you can simulate with 1min as well as 1h resolution. In 1min resolution you can also simulate effects like irradiance enhancements and the like.

To your questions:

  • LID: The light induced degradation goes into the module degradation, which you can enter for each module area separately.
  • Module Quality Loss: If you refer to a degradation of the overall module performance over time here, you would enter this in the module degradation as well
  • Thermal Loss Factor: This is a parameter of the PV module that you use. You can either just use a PV module from the database, or you can enter your own. There are three temperature coefficients: for the short circuit current in mA/K (or %/K), the open circuit voltage in mV/K (or %/K) and the MPP power in %/K.
  • Module mismatch losses/string mismatch losses:
    • There is a overall module mismatch loss factor that you can enter in the project options, usually set to 2%. This will cope for the losses to expect from module sorting (i.e. the fact that modules usually don't have the exact power output that is written on the datasheet)
    • The real losses in the modules and strings that you have due to shading are simulated with the help of a very detailed algorithm. For each time step we determine where the shadows are, how many substrings of the module are shaded, calculate the resulting IV characteristics and finally overlay them to string IV curves. From these (and the chosen working point) the losses are calculated
  • IAM loss factor: This is also a factor that is entered in the module data.

If you have further questions, please feel free to ask.

Kind regards,


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