The sensitivity analysis option allows you to specify a range of values as a percentage for one or more input variables to investigate how sensitive an output metric is to variations in the input variables' values. Examples of sensitivity analyses include:

Configuring sensitivity analyses makes it possible to plot tornado graphs showing the range of an output metric values for one or more sensitivity variables.

Note. Solar Advisor calculates results for each sensitivity variable independently. In some analyses, this may cause misleading results. This is especially true when the sensitivity variable is a performance input variable rather than a cost or financial input variable. For example, for CSP trough systems with storage, varying the thermal storage capacity independently of the tank heat loss variable to examine how sensitive the system's electrical output is to storage capacity would not accurately account for the expected increase in heat loss for larger storage systems. Similarly, for photovoltaic systems, varying the number of modules per string independently of the inverter type or number of inverters might result in inaccurate system output calculations if the inverter is improperly sized for a number of modules within the range specified for the sensitivity analysis.

To display the sensitivity simulation setup options:

Click Remove Simulation to delete a simulation option.

Click Clear All to remove all simulation options from the case.

The Analysis Setup options allow you to choose an output metric, add and remove variables from the list of sensitivity variables, assign values to and edit sensitivity variables, and assign ranges to each sensitivity variable.

Analysis Setup

Select an output metric

Choose an output metric for the sensitivity analysis. This metric will appear on tornado graphs in the results.

Add

Add an input variable to the sensitivity variables list.

Edit

Assign a "custom" variation range to the variable highlighted in the sensitivity variables list. Solar Advisor assigns the default range to all sensitivity variables that do not have a different custom range. Solar Advisor indicates the custom range in parentheses next to the variable's name in the sensitivity variable list.

Remove

Remove a variable from the sensitivity variables list.

+/- Variation on inputs

The default range applied to all sensitivity variables that do not have a different custom range. For a range value of 10 %, Solar Advisor would calculate the range of values of an input variable between 10 % below and 10 % above the variable's value on the input page.

Once you have added a sensitivity simulation, you must add one or more sensitivity variables to the simulation.

After setting up the optimization, click the Run All Simulations button, or click Run All Simulations on the Case menu to run the optimization and any other enabled simulations.

To set up a sensitivity analysis:

The following tornado graphs were created by setting up sensitivity analyses. You can use these examples to better understand how to use parametric analysis to create useful graphs.

The following graph shows how sensitive a CSP trough project's levelized cost of energy is to four capital cost categories. To create the graph, the following four variables were defined as sensitivity variables using the default variation range of 10 %: Power plant cost, solar field cost, HTF system cost, and storage system cost:

The next graph shows shows how sensitive the levelized cost of energy is to selected capital cost categories compared to selected financial assumptions for a CSP trough system. The solar field cost, loan rate, and PPA escalation rate were defined as sensitivity variables with a 10 % variation range. how the first year annual electric output depends on both the array tilt and azimuth. The tilt variable was assigned the same values as the previous graph, and the azimuth variable was assigned values between -90 and 90 degrees west of south in increments of 15 degrees: