Thermal comparison of mono-facial and bi-facial photovoltaic cells considering the effect of TPT layer absorptivity

Abstract

With the widespread utilization of solar photovoltaics (PV), it is becoming increasingly important to understand its performance using various configurations to harvest solar energy at the most suitable efficiency, specifically in hot climates. Therefore, this paper compares mono-facial and bi-facial PV cells under the high-temperature desert climate of Sharjah (United Arab Emirates). The optimally tilted and vertical east-west configurations were compared to evaluate the annual energy production for these scenarios. In addition, new parameter, the effect of the rear side layer absorptivity of the mono-facial PV cell, was investigated. The comparative study considered solar radiation, ambient temperature, wind speed, and albedo. The results showed that considering the effect of absorptivity achieves better performance predictions. However, the effect of the absorptivity did not exhibit a significant influence compared to the case with neglected backsheet absorptivity. As such, the PV cell temperature increased by 0.4 °C and 1.4 °C at an albedo of 0.2 and 0.7, considering the actual absorptivity value of 0.2. On the other hand, it is worth mentioning that improper designs result in considerable temperature rises as the absorptivity value increases. Under the investigated conditions and based on the yearlong comparison, the tilted bi-facial performed better than the vertical bi-facial; as the albedo increased from 0.2 to 0.7, the power gain ratio of the tilted bi-facial increased from 7.18% to 20.88% and that of vertical bi-facial from -19.4% to 12.65%.

Keywords

• Photovoltaic
• Mono-facial
• Bi-facial
• Thermal modelling
• Efficiency