An investigation into harvesting solar energy using thermoelectric generator coupled IBR sheeting

Abstract

There is a current global impending need for clean and renewable energy sources. Fossil fuels are non-renewable finite resources, which are dwindling because of high cost, and environmentally damaging retrieval techniques. South Africa’s coal resources may soon reach their end, which further stresses the need for green energy. An efficient and more feasible alternative is solar energy. Thermoelectric generators (TEGs) may use the energy from the sun to generate power and are an innovative means to harvest electricity. The proposed study intends to validate whether TEGs are a potential method to harvesting solar power. The study herein is a preliminary experimental investigation into a development in a TEG modular prototype. Relevant tests are run, and the performance characteristics obtained from experiments are discussed. The TEG system developed and tested in this study consists of 2 equally sized pieces of Inverted Box Rib (IBR) sheeting with one side exposed to a light source, while the other side remains shaded. An Arduino, connected and coded to read and display resulting temperatures, Peltier tiles, magnets, simple heatsinks and Multimeters are connected to measure open circuit voltage and closed-circuit current generated from the temperature difference between the two sides of the IBR sheeting. The system aims to harvest energy whilst keeping the assembly and construction simple, practical, and minimalistic. Outdoor experiments were conducted to determine the temperatures and the resultant temperature gradients the configuration may experience in operation. The data collected established parameters for the laboratory experimental setup. The laboratory experiments characterized the power output of the units. For comparative purposes, some variables were removed, such that the testing variable was isolated. Some environmental variables were removed by testing in a laboratory. The TEG was tested in the vertical position to allow for maximum natural convection, and hence may not reflect results that would be obtained in all applications. The TEG system is exposed to the light source at different distances, perpendicular to the sheets. The study intends to investigate the effect that the 2 variables have on the amount of solar power generated i.e., the colour of metal IBR sheeting, and the ideal electrical arrangement for scalability of Peltier tiles for maximum power output (𝑃𝑚𝑎𝑥). The IV curve generation method (later explained in chapter 2.4.1) is used to read the parameters required to calculate 𝑃𝑚𝑎𝑥. The results show a strong influence of the black coated sheets on the power output of the TEGs. It is deduced from solar experiments, that the aluminium rods used as the heatsink fulfilled its purpose of regulating a ∆T of 1-2°𝐶. Furthermore, the TEG in series configuration, generated the highest 𝑃𝑚𝑎𝑥 when located 300mm from the heat source, followed by 600mm and lastly, 900mm. The same pattern is found for the unit and parallel configurations. It may be concluded from the proposed TEG system that TEGs are a potential method of harvesting solar energy on IBR sheeting, specifically in a vertical position. However, applications of different orientations and geographical locations require further investigation. The results merit further investigation and refinement into the use of TEGs on IBR sheeting where the herein designed TEG system is set-up in a user friendly, simple, cost effective and practical manner for solar energy harvesting. While the power output per TEG tile is small in magnitude, the proposed configuration has potential in the coupling of multiple units to increase power output. The current work shows potential for the use of TEGs in this application. Through further investigation, refinement and cost analysis, the system may prove to be a practical method of solar energy harvesting.