Need weather input format for P50/P90 analysis

Is it possible to post the format definition for the .cbwfdb files used as input for the P50/P90 analysis? We need to analyze our own multi-year data sets.

Also can you describe how the annual degradation factor is used in the P50/P90 analysis? The time series of annual production does not appear to be diminished by the degradation factor input.

Hello,

The .cbwfdb file format is a proprietary format that we developed for SAM's P50/P90 capability to protect the NCDC's data. They allowed us to use the data under the condition that we not make the weather data available to the public, only results from SAM runs on the data.

To address your request, we have implemented a new feature that makes it possible to use the P50/P90 capability when you have a set of 15 or more weather files in one of the formats SAM can read (TMY2, TMY3, EPW, SMW). You will be able to test the capability in next month's Beta release, and it will be part of the Fall 2012 version.

As for degradation, SAM calculates the total annual electricity output for each year using the data in the weather file for that year without applying the degradation rate. That means that the "Net Annual Energy" P50 and P90 values do not include the effect of the degradation rate that you specify on the Annual Performance page.

On the other hand, the LCOE P50 and P90 values do include the effect of degradation, although not in the way you might expect. SAM calculates an LCOE value over the analysis period for each weather file year, and then sorts the resulting LCOE values to determine the P50 and P90 values.

Best regards,
Paul.

Excellent news Paul. Any idea when the Beta will be available?

The Beta version will be available around the end of September 2012. If your account notification settings are set to receive newsletters from the SAM website, then you will receive an announcement with instructions when it is ready.

Best regards,
Paul.