AE 868
Commercial Solar Electric Systems



Lesson 5 Scenario

Finishing the scenario we started, after choosing the PV Module, Inverter, and/or Storage devices for your PV system, your last stop at the solar trade show should be for the complementary components needed to put the system mechanically together and to allow the system to be electrically connected to an application such as grid or load. These electrical and mechanical components are referred to as Balance of System, or (BOS) for short.

Suppose your company is a small company that deals with residential installations. What type of mounting systems would you be looking for? Is it a roof mount or a ground mount system?

The representative asks you about the territory that you work mostly within to help you with the structural and mechanical loads calculations based on the recommended manufacturer specification. As a PV designer, what do you provide to him? Is it wind speed, snow load, roof pitch, or system layout to help run his calculations?

Suppose your company installs rural and large PV systems. In this case, what mounting type will you be interested in? What factors play a role when selecting the module racking? Is it the module mounting type? Or dimensions of your modules?

The representative gives you an idea about what they carry for these installation types. He offers you other solutions that complement the mounting structure. What are these Mechanical Balances of Systems that can be combined with the racking structure to help fasten the PV modules to the structure?

Since the PV system is an electrical system that generates power to loads/ grid, what are these components that help deliver energy to loads, and how do these Electrical BOSs relate to the mechanical BOS components? Since you are a company operating in the U.S., can any BOS be installed, or should it meet some kind of test standards and certifications?

In this lesson, we will discuss topics that lead to answers to all the questions in the scenario above. We will teach PV designers basic BOS components they should look for to fit their applications. Learning the topics taught in this lesson will help a variety of audiences, ranging from system designers or installers to business owners.

Learning Outcomes

At the successful completion of this lesson, students should be able to:

  • Identify main electrical and mechanical BOS.
  • Identify main types of racking systems including rooftop, ground mount, and pole mount PV systems.
  • Indicate factors that affect the decision to choose types of mounting systems and their requirements.
  • Differentiate between various types of attachment methods.

What is due for Lesson 5?

Lesson 5 will take us one week to complete. Please refer to the Calendar in Canvas for specific time frames and due dates. Specific directions for the assignments below can be found within this lesson and/or in Canvas.

Complete the following Lesson Assignments:

  • Read through the Lesson Content
  • Complete the Required Reading Assignments:
    • Chapters 10 and 11, Photovoltaic Systems by James P. Dunlop (text) (Note: We will revisit Chapter 11 again in Lesson 8.)
  • Complete the Lesson 5 Activity
  • Complete the Procurement Report/Peer Review
  • Take the Lesson 5 Quiz in Canvas


If you have lesson specific questions, please feel free to post to the Lesson 5 Questions discussion forum in Canvas. While you are there, feel free to post your own responses if you, too, are able to help a classmate with a question. If you have questions about the overall course or wish to share and discuss any "extra" course related commentary (interesting articles, etc.), please feel free to post to the General Questions and Discussion forum.