EME 812
Utility Solar Power and Concentration




This lesson will introduce the concept of sun tracking and will discuss how it can improve the performance of solar energy systems. The sun is a light source that is not fixed, but rather is constantly moving relative to a solar receiver. This leads to significant variability of the available radiation and, as a result, variability of power output and efficiency of a solar energy conversion system. The idea of sun tracking was developed in attempt to mitigate that variability to some extent and in pursuit of higher efficiency and extending the solar power production over the course of the day. Tracking technology is more often associated with utility scale solar plants rather than small residential systems. Some examples of tracking include single-axis and two-axis tracking of PV panels, moving heliostats in solar tower thermal plants, variable tilt parabolic trough systems, and Stirling dish concentrators - systems whose operation heavily relies on the accuracy of tracking. In this lesson, we will first discuss when tracking is a viable idea, and what systems can benefit from it. Then, we will study the geometry of the solar motion through the sky and define the parameters that characterize the position of the sun relative to a solar receiver at a certain location and time. This background would be important in understanding any tracking algorithms. Some examples and activities within this lesson will involve geometric calculations that will help you to better understand how this technology works.

Learning Objectives

By the end of this lesson, you should be able to:

  1. define the main parameters of the solar motion;
  2. explain the types of tracking systems and principles of their operation;
  3. calculate the position of the sun relative to the receiving surface at a locale at a particular time.


Kaligirou, A, Solar Energy Engineering, Chapter 2: Environmental Characteristics.

Brownson, J.R.S., Solar Energy Conversion Systems, Chapter 7. Applying the Angles to Shadows and Tracking, pp. 192-196.

Both books are available for reading online through the Penn State Library system. See the "Library Resources" / E-Reserves tab in Canvas.