The Uncertainties inputs allow you to specify uncertainty as a percentage of either mean wind speed or mean energy production for a range of different factors that contribute to uncertainty in the the wind resource or power output of a wind farm.

When you enable uncertainties, SAM calculates probability distributions of annual electricity production and displays them on the Uncertainties tab of the Results page. It also displays a p90 energy value in the Metrics table on the Summary tab.

The uncertainty model draws from the IEC 61400-15 uncertainty framework as described in Damiani, R. (2018). Uncertainty and Risk Assessment in the Design Process for Wind. National Renewable Energy Laboratory, NREL/TP-5000-67499 (PDF 8.9 MB).

Note. The uncertainty model requires a good understanding of the IEC framework described in Damiani (2018).

To use the uncertainty model:

1.Choose Enable Uncertainty Analysis.

2.Review the uncertainty inputs for wind resource and energy-related uncertainties and modify as appropriate for your analysis. Note the calculated total project uncertainties at the bottom of the page.

3.Review and modify as appropriate the inputs on the Losses page.

4.Run a simulation.

5.On the Results page, review the p90 value in the Metrics table on the Summary tab, and the distribution tables and graphs on the Uncertainties tab.