Lesson 2 of 8
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2. Defining Your Analysis Goal

Here’s a short exercise to help you focus your analysis on a specific question and think through how to use SAM to answer it.

Before you begin your work in SAM, write a question to focus your modeling work on a specific answer. You will use SAM to develop an answer based on your analysis and understanding of the inputs you provide and the simulation results. SAM is a tool you can use to answer the question, SAM itself does not provide answers.

Once you know the question you are trying to answer, choose the model configuration in SAM that best helps answer the question. For example, you might choose the Detailed PV / Residential configuration to answer the question “What string size should I use for a given inverter for a residential rooftop photovoltaic system?”

Use the question to prioritize inputs: Choose which inputs to modify and which ones to leave at default their value. For this question, you would focus on the module, inverter, and system layout inputs. You could use default values for shading and losses, costs, and financial inputs because they are not directly relevant to the question.

When you run a simulation, choose the simulation results that best help answer the question. In this case, system performance factor, the clipping loss, and array operating voltage outputs would be useful outputs.

Identify limitations of the model and determine what parts of the question may require other tools or resources: SAM’s simulation results may not be useful for some parts of the question. For example, because SAM does not have information about the size, shape, or position of pipes and other objects on the roof, you would have to use other resources such as measurements and photographs of the roof to determine how the roof’s design might affect the string size.

Finally, decide how best to present simulation results to illustrate the answer to your question. You might export images of graphs and tables from SAM, or export data from the simulation results to other software to create your own graphs and tables.

Here are some examples of analysis questions:

  • How much electricity can I expect a 6 kW PV system to generate in a given location?
  • Will a fixed array or array with trackers be most cost-effective for my ground-mounted PV array?
  • What power price should I negotiate to meet my project’s return-on-investment requirements?
  • What size of loan should I take out for my project?
  • How many modules and inverters will I need for a 10 MW system?


  • Think of and write down three analysis questions that you want to use SAM to help answer.
  • At the end of the course, for each question, decide whether SAM is the right tool to answer the question. If so, answer the following questions before starting your work in SAM:
    • What model configuration will best help answer the question?
    • What inputs will you need to modify from their default values for this analysis?
    • What input data will you need to collect?
    • What output data will you use to answer your question?
    • How will you present this data to support your answer?