Title

Passive Solar Tracking Using Shape Memory Alloys

Date of Award

2019

Document Type

Thesis

Department

Physics

First Advisor

Dr. Angela Douglass

Second Advisor

Dr. Kevin Cornelius

Third Advisor

Dr. Barbara Pemberton

Abstract

The world's energy demands are growing daily in conjunction with the global population and urbanization. In the modern era, the main source of energy has come from nonrenewable fossil fuels. While this source is one of the cheapest forms of energy, it is also one of the worst for the environment and will only last until the earth runs out of these fossil fuels. Solar energy, on the other hand, is both much better for the environment and an inexhaustible resource. The primary issue that arises with the accessibility of solar energy is that it is much more expensive per watt of power when compared to other sources like oil. However, solar power could become more affordable by increasing the efficiency with which it is generated, and one of the most promising methods of doing so is by solar tracking.

In this study, a novel passive tracker was designed and tested with the purpose of increasing solar panel efficiency. Intending to build a low maintenance, low cost, stand-alone system for powering a street light, the design was fabricated and tested against a fixed solar panel system for comparison.

Of specific interest in the project was the motor used to drive the solar tracker. The tracking mechanism designed in this research differed from other trackers because it was passive, inexpensive, utilized shape memory alloys, and increased overall power output and efficiency without requiring any extra power input. Other passive trackers have been designed using shape memory materials, photodiodes, bimetallic strips, and volatile gases. This design employed shape memory alloy springs and Fresnel lenses to drive the motor.

Efficiency was tested versus fixed panels by mimicking the angle a tracker would have set the panel to, and measuring the power output at both this angle and at a fixed solar panel's orientation. Analyses of the results showed an increased power output such that the percent difference relative to fixed solar panel systems was, on average, 62.77%. While this high percentage is indicative of the energy gain potential on sunny days, not overcast or rainy days, it does confirm quantitatively that solar tracking is beneficial in the geographical region of interest in the project, Arkadelphia, Arkansas.

In addition to detailing the design process and efficiency testing of the solar panel tracking mechanism, background investigation into shape memory alloys and solar panels will be discussed, and a brief inquiry into gear train mechanisms that were analyzed as being potentially beneficial to the motor design will be summarized.

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