P50/P90 Analysis

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P90 sim using SSC/SDK

Need to run P90 simulations using a script. However, can't find a module in ssc.dll which will perform P90 simulations.
Have i missed something or is there a work around?


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Generate P90 "TMY" Files from Longterm Timeseries Data


Does SAM have the ability to generate TMY files to a set confidence interval? I suppose these wouldn't be typical (P50) anymore, but the point is to represent with a single 8760 hourly file the solar + weather resource to a particular level. It would have all of the same compromises and utility as a standard TMY file.

Data for P50/P90 Simulations

As of SAM 2017.9.5, you can download multiple weather files for P50/P90 simulations directly from SAM's Location and Resource input page. We made a short video showing how to do that.

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Change variables analyzed when running P50/P90

I am trying to modify the list of metrics that are calculated when running the P50/P90 simulation.

I´ve seen in HELP that this may be done under "Configure Simulations", but I´ve not been able to find this option in the latest SAM version.

How can I select different variable to appear when running the P50/P90 simulation?

I am attaching the default metrics the system is currently calculating.


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P50/P90 Net Annual Energy Production for PV System

How do you determine the P50/P90 Net Annual Energy Production for a PV System? The P50/P90 energy values are much greater than the net annual energy production values given in the simulation. How do you determine the energy produced that includes energy losses?

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I am looking to find the expected P50 net annual energy production for each year of a 25 year plan. SAM P50/P90 simulation only provides the net annual production for one year. I would like to know if anyone knows how I can obtain this data.

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Weather files not working P50/P90 run

Below is the error when i run the P50/P90 analysis and the log file shows this error in every year in the Chicago folder and also with all the files in the Rockford folder.

Line 1 has 7 columns with this data "94846 CHICAGO IL -6 41.783 -87.75 190" and all the .csv files are the same and the error msg says 10 are required.

\Historical NSRDB 1961-1990 Beta\IL ROCKFORD/94822_1962.csv error reading header (line 1). At least 10 columns required, 7 found.

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P50/P90 weather files


I am thinking of using the P50/P90 analysis in SAM, and wanted to test it out. Could you point me to the location of the sample files that are already downloaded? Note: I also tried going to the link that is given in the help pages, http://en.openei.org/datasets/node/872, but didn't find the data there.

Best regards,

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Recognizing Weather Data in P50/P90 Analysis


I am having issues with SAM recognizing weather files for P50/P90 analysis. I have 15 years of weather data for my particular project site in TMY format. (I have also converted it to SAM format using the macro functionality, but that did not seem to help.) I can run each of the files individually in a normal simulation run, but when I try to point to the file folder for P50/P90 analysis it does not recognize the files. SAM indicates that "it is not possible to empirically determine the P90 value with less than 10 years of weather data".

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P50/P90 File

I am trying to locate the P50/P90 Full Weather Database file sam-weather-data-ncdc_2011-11-10.cbwfdb. I have gone through the links on OpenEI but there is no link to download the file. Here is the link I found the file reference on.


I am trying to perform an analysis on a site located near the Imperial Valley in Southern California. Any help is appreciated.

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