A parametric analysis involves assigning multiple values to one or more input variables to explore the relationship between the input variables and results metrics. Examples of parametric analyses include:
| • | For photovoltaic systems, exploring the effect of array orientation on system electricity output by assigning multiple values to the array tilt and orientation variables. |
| • | For CSP trough systems with thermal energy storage, exploring the effect of solar multiple and storage capacity on the levelized cost of energy. |
| • | For any technology, exploring the effect of annual degradation rates on the system's annual energy output over the life of a project. |
Configuring parametric variables makes it possible to plot graphs of performance or economic output metrics as a function of one or more input variables. For example, to plot a graph of the annual electric generation performance metric and the array tilt input variable, you would need to define the array tilt variable as a parametric variable. Parametric variables also appear on sliders, allowing you to dynamically change graphs and tables on the Results page.
Note. Input variables that are not involved in the performance simulation calculations, such as those on the financing, tax credit and payment incentives, and utility rate pages, are available as sliders without being defined as parametric variables.
To display the parametric simulation setup options:
| 1. | On the Main window, click Configure Simulations to view the Configure Simulation page. |
| 2. | On the Configure Simulations page, click Parametrics to display the Parametric simulation setup options. |
| 3. | Click Add Parametric Simulation to add a set of parametric simulation setup options. You can add as many parametric simulations as your analysis requires. |
Click Remove Simulation to delete a simulation option.
Click Clear All to remove all simulation options from the case.
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The Parametric Simulation Setup options allow you to add and remove variables from the list of parametric variables, assign values to and edit parametric variables, and to set up linkages between parametric variables that have interdependent values.
Parametric Simulation Setup
Add
Add an input variable to the parametric variables list. You must add a variable before you can assign it multiple values.
Remove
Remove a variable from the parametric variables list. When you remove a variable, Solar Advisor assigns the value from the variable's input page to the variable.
Setup Linkages
Create linkages between parametric variables when the values of one of the variables is dependent on those of the other.
Edit
Assign values to or edit values of the variable highlighted in the parametric variables list.
Up
Move the highlighted value in the variable values list up one row.
Down
Move the highlighted value in the variable values list down one row.
Remove Simulation
Remove the parametric simulation setup and delete all parametric values. You can also clear the Enable this simulation checkbox to keep the setup options but exclude the parametric analysis from simulations.
Enable this simulation
This box must be checked for the parametric simulation setup to be included in simulations when you run the model.
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Once you have added a parametric simulation, you must add one or more parametric variables to the simulation, and assign multiple values to each variable.
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 parametric analysis:
| 1. | Display the parametric simulation setup options as described above. |
| 2. | Click Add to choose variables to which you want to assign multiple values from a list of available input variables. Solar Advisor adds the variables to the parametric variables list. |
| 3. | Highlight each variable in the parametric variables list and click Edit to assign values to the variables. See Working with Numeric Ranges for details. |
| 4. | Check Enable this simulation to include the parametric analysis in simulation runs. You can save the parametric simulation setup options and exclude the analysis from simulations by clearing the checkbox. Clearing the checkbox allows you to shorten simulation run times without losing the setup configuration. |
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In some analyses, parametric variables may be interdependent. For example:
| • | Tilt depends on location when an analysis assumes that the photovoltaic array or CSP collector tilt angle is equal to the location's latitude. |
| • | Thermal storage capacity depends on the solar multiple for a CSP trough analysis that assumes that the storage system capacity scales with the solar field area. |
For these analyses, linking the interdependent parametric variables prevents Solar Advisor from simulating combinations of parametric variable values that are not relevant to the analysis. For example, linking the array or collector tilt variable to the location variable ensures that Solar Advisor only simulates systems that use a location's latitude as the tilt angle. Without linkages, Solar Advisor would simulate all combinations of locations and tilt values.
To setup a linkage between two parametric variables:
| 1. | Add the two variables to the parametric variables list as described above. The parametric variables list may include other variables. |
| 3. | In the Choose Linked Parametric Variables window, check the variable names for each of the two linked variables. |
| 4. | Click OK. Solar Advisor displays the word "Linked" in brackets next to the variable names in the parametric variables list indicating the linked variables |
| 5. | Click the first linked variable. Solar Advisor displays the variable's values in the variable values list, and shows the value of the other linked variable in brackets. |
| 7. | Click OK. Solar Advisor displays question marks in brackets next to the values of the second linked variable to which you have not yet assigned values. |
| 8. | In the parametric variables list, click the second linked variable. |
| 9. | Click Edit to assign multiple values to the variable. Note that you should assign the same number of values to this variable as you did to the first linked variable. |
| 10. | Click OK. Solar Advisor displays the values of both variables in the variable values list. Check the list to make sure that there are no question marks in brackets indicating a missing linked value and that the values are in correctly matched pairs. |
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The following graphs were created by setting up parametric analyses. You can use these examples to better understand how to use parametric analysis to create useful graphs.
The following graph shows how a photovoltaic system's first year annual electric output depends on the array tilt. The tilt variable on the Climate page was defined as a parametric variable with ten values: 0, 10, 20, 30, 40, 50, 60, 70, 80, and 90 degrees from horizontal:
The next graph shows 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:
The third graph shows the relationship between the first year annual electric output and array azimuth for three locations, assuming an array tilt equal to the location's latitude. The azimuth value was assigned ranges between -90 and 90 degrees as above, and the tilt and location variables were linked as follows: Location = Boulder : Tilt = 40 degrees, Location = Los Angeles : Tilt = 34 degrees, Location = New York City : Tilt = 41 degrees. Each cluster of bars in the graph shows the annual energy output for each azimuth value for Boulder, Los Angeles, and New York, respectively.
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