Session: ASME Undergraduate Student Design Expo

Paper Number: 175905

Theoretical and Experimental Investigation of a Bifacial Photovoltaic Module 

Solar panels are an inefficient method of energy conversion, with an average efficiency of around 15%. Bifacial modules can serve as one possible solution to these problems by having a secondary surface to collect additional incident flux using diffused solar energy. Bifacial solar technology has the potential to revolutionize renewable energy production through industrial implementations. The additional energy collected requires a reflective ground surface for maximum output. Understanding the albedo of the ground and the azimuth angles is key to optimizing the panel. To fully utilize the capabilities of the bifacial photovoltaic module, a theoretical and experimental analysis was conducted using multiple software, electrical, and mechanical components. In SolidWorks, a panel was modeled as a series of individual layers: aluminum frame, glass, polyvinyl fluoride, ethylene vinyl acetate, and photovoltaic cells, second ethylene vinyl acetate, and glass stacked on one another to reflect the inner workings of a solar panel. In Ansys Fluent, the model of the panel was imported, and to simulate the thermal properties, material values were assigned. Individual properties for each layer included thermal conductivity, specific heat, and density. A mesh size of 5mm was assigned, resulting in 233,200 elements and 80,000 nodes across the panel. Two different heat fluxes were assigned to the panel to simulate direct and indirect sunlight. The power of these fluxes would be changed to simulate indoor and outdoor conditions. Convection was applied to all surfaces to simulate real-world passive cooling with a heat transfer value of 5W/m2K for indoors and a variable rate based on temperature range. For indoors, the temperature was controlled at 21o Celsius, and for outdoors, there was a range of 15-27o Celsius. In order to determine the direct and indirect sunlight heat flux values, a Bird Clear Sky Model was utilized to estimate values for testing purposes. For indoor calculations, the incident flux on the upper surface of the panel was estimated at around 300 W/m2, whereas the back panel was about 26.5 W/m2. The corresponding values for the outdoor simulation were around 800 W/m2 and 70 W/m2. The monofacial and bifacial temperatures reached a maximum of 44.91o Celsius and 49.21o Celsius, respectively, in one hour. Higher surface temperature in the case of a bifacial panel does indicate an overall higher incident flux on both panel surfaces. The higher flux means high output power from the bifacial panel as compared to the monofacial panel. To validate further, experimental work was conducted with a bifacial solar panel [JJN-200W] with various ground reflective surfaces, including turf, sand, aluminum, gravel, concrete, and glass. 

 

To reference the power increase that results from the use of the bifacial panel, the panel’s IV characteristics are required. Using a variable resistor module, both values were obtained, and power was calculated. Indoor and Outdoor testing was conducted to understand both environments. The former implemented two halogen lamps to simulate the sun. In both scenarios, various materials with different reflective capabilities were used. Tests were run for one-hour periods. In addition to power measurements, results were also collected using 8 thermocouples and a TC-08 data logger. The variables collected included current, voltage, power, albedo, and temperature. Our results indicated a 39.9% increase in the max output power as the monofacial panel was replaced by a bifacial panel with aluminum as the ground reflecting surface. A similar trend was observed as the aluminum reflecting surface was replaced by turf and rock, though the power increase in both cases was marginal. This poster will provide detailed experimental and theoretical results and propose a practical method to improve the ground reflection by adding a layer underneath the solar panel. 

Presenting Author: Akhil Manikandan American High School

Presenting Author Biography: As a research intern at San Jose State University (Department of Mechanical Engineering), my research activities are related to the renewable energy resources. I am conducting research in the area of solar panels and would like to continue research in this field in coming years and want to cover both experimental and theoretical modeling for these projects.

Authors:

Sohail Zaidi San Jose State University
Akhil Manikandan American High School
Omkar Anand California High School