AE 868
Commercial Solar Electric Systems



Lesson 12 Scenario

You work at one of the utility companies that is analyzing a renewable rebate structure. The ultimate plan is to allow higher renewable penetration to meet the vision for the next decade of the company’s clean energy portfolio. You are in charge of analyzing the load profiles at certain electrical feeders to predict the impact of the additional capacity on the grid. After reviewing the data collected on these feeders, your task is to accurately determine the maximum allowable renewable capacity at each interconnection point that will result in minimal grid effect. What do you look for when deciding the system size in regards to the load demand profile? Is there an impact of massive grid-connected PV systems at each point on the grid? What are the main concerns that the utilities face when dealing with different levels of renewable penetration.

For many decades, the electricity demand has followed what can be considered as a predictable daily pattern. This pattern allows utilities to perfectly predict future demand so that they can prepare themselves for buying and selling the electricity as in the energy market.

As more electricity is being generated from renewable resources with the largest share of solar technologies, this addition to the utility grid introduces changes to the traditional daily profile of the electricity demand. These changes bring challenges with them to utilities to address reliability issues. In this lesson, we will introduce the electricity demand profile and the challenges to utilities after adding solar systems in large capacities. In addition, we will introduce this effect by what is referred to as the "Duck Curve," and later in the lesson we will talk about a proposed solution to that effect.

Ultimately, this lesson helps our solar professionals understand the back-end effect on PV and other renewable energy resources in the utility grid. Whether you work for an electric utility or you are a PV designer at an engineering firm, understanding the bigger picture on deploying PV technology helps in analyzing how the industry is driven and how to adapt to these changes. 

Let’s get started!

Learning Outcomes

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

  • Describe predicted load profile viewed from the utility side.
  • Discuss challenges of excessive PV interconnection on the utility grid.

What is due for Lesson 12?

Lesson 12 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:


If you have lesson specific questions, please feel free to post to the Lesson 12 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.