Optimization

An optimization involves choosing an output metric that you would like to either maximize or minimize, and allowing Solar Advisor to find values of one or more input variables that result in the maximum or minimum output metric value. Examples of optimization include:

•	For photovoltaic systems, finding the array tilt and azimuth values that result in the lowest levelized cost of energy to optimize the array orientation for lowest cost of energy.

•	For a photovoltaic system modeled using the PVWatts performance model, optimize the storage capacity for minimum levelized cost of energy.

•	For a CSP trough system, find the optimal collector deploy and stow angle to maximize solar field thermal output.

Note. When you optimize an input variable, be careful to choose one that is not interdependent on other variables. For example, for a CSP trough system with storage, optimizing the solar multiple independent of storage capacity to minimize the levelized cost of energy could give misleading results. Similarly, for photovoltaic systems, optimizing the number of modules per string independently of the inverter might result in a system with an improperly sized inverter. To find optimal values of interdependent variables, you can use parametric analysis.

One application of Solar Advisor's optimization capability is to help you find values of input variables to use for your analysis. For example, for a photovoltaic system, you could use optimization to find the best array tilt and azimuth values to use on the Array page. Or, for a CSP trough system, you could use optimization to find the deploy and stow angle to use on the Solar Field page.

To display the optimization setup options:

1.	On the Main window, click Configure Simulations to view the Configure Simulation page.

2.	On the Configure Simulations page, click Optimization to display the optimization simulation setup options.

SS_ConfigureSimulations-OptimizationClick

3.	Click Add Optimization Simulation to add a set of optimization 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.

Contents

►	Page Reference describes the optimization simulation setup options.

►	Setting up an Optimization describes the steps for defining optimization variables.

►	Sample Optimization Results shows examples of results from an optimization analysis.

Page Reference

The Optimization Setup options allow you to select the output metric to maximize or minimize, add and remove variables from the list of optimization variables, and assign a range of values to optimization variables.

SS_Optimization-Overview

Optimization Setup

Minimize / Maximize	Choose whether to maximize or minimize the output metric.
Select an output metric	Choose the output metric to maximize or minimize.
Add	Choose one or more optimization variables from a list of available input variables.
Edit limits	Assign an upper and lower limit to the variable highlighted in the optimization variable list.
Remove	Remove the highlighted variable from the optimization variable list.
Advanced parameters	The advanced parameters affect the speed and resolution of the optimization. You can use the default values for most analyses, or experiment with the values for faster run times. You can also try adjusting the values if Solar Advisor does not find an optimal solution.

Setting up an Optimization

Once you have added an optimization simulation, you must choose an output metric to maximize or minimize, add one or more optimization variables to the simulation, and edit the limits of 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 an optimization:

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 an upper and lower limit to each variable.

4.	Check Enable this simulation to include the optimization in simulation runs. You can save the optimization 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.

SS_Parametrics-Enable

Sample Optimization Results

The following example illustrates the use of optimization for Solar Advisor analyses.

This example is for a CSP trough system, and finds the optimal collector deploy and stow angles defined on the Solar Field page. Those angles determine the collector angle at which heat transfer fluid begins circulating in the morning, and stops circulating in the evening, respectively. The system starts tracking the movement of the sun at sunrise, but deploying collectors too early results in wasted energy from operating fluid pumps before there is sufficient energy to generate electricity. Similarly, continuing to operate the fluid pumps in the evening when the sun is below a certain point above the horizon wastes energy. Optimizing the deploy and stow angles for maximum thermal energy delivered by the solar field ensures that the system does not waste energy by deploying the collectors too late or stowing them too early. In this example for a system in Dagget, California, Solar Advisor found an optimal deploy angle of 12 degrees, and an optimal stow angle of 167 degrees. The optimization found the maximum value of the annual thermal energy from solar field output metric for deploy angle limits of 0 and 20 degrees, and stow angle limits of 160 to 180 degrees:

SS_Optmization-StowDeployGraph