PV Module Wattage / Electrical Parameters Tolerance

Hello,

I would just like to get some insight into whether SAM is considering any variance or tolerance on the PV module STC electrical parameters, especially if the PV module datasheet says something like "Power tolerance 0~5W", or, like one datasheet I am working with currently, that indicates +/-3% tolerance to any STC electrical parameter. I do not see any way to specify this variance in the SAM PV module model, but this seems like it could make a significant difference in how VOC is calculated and reported.

Thank you,
Kyle Dean, P.E.

Hi Kyle,

When you run a simulation in SAM's Detailed PV or PVWatts model, it does not account for uncertainty in the module's STC rating or other factors.

When you have a set of ten or more weather files for a series of years, you can use the Uncertainty option (click Uncertainty under the Simulate button) to explore the impact on total annual energy production of ranges of uncertainty for different input variables.

For your analysis, you could use the "CEC Performance Model with User Entered Specification" option on the Module page to create a copy of the module parameters and then modify them to explore the effect of ranges in the module's parameters on the operating Voc and other output variables.

 

Click the Copy specifications from currently selected module in CEC database to copy the parameters.

If you are doing a lot of this kind of analysis, you could use LK script to write a program to automatically evaluate ranges of parameters:  sam.nrel.gov/lk-script.html

Best regards,
Paul.