Improved Efficiency and Longevity of Solar PV Systems Through Enhanced Passive Convection

Abstract

Solar PV technology is growing rapidly and becoming a crucial part of international and national energy infrastructure. Current commercially sold Si solar PV (Photovoltaic) panels, with ~21% efficiency and a projected lifespan of 25-30 years, face performance challenges influenced by operating climate. Efficiency losses arise from factors like potential induced degradation, thermal losses, low irradiance, reflection, and soiling. Over time, panel efficiency degrades due to mechanisms such as micro-cracking, contact diffusion, moisture ingress, and back sheet delamination, which are accelerated by high temperatures and temperature fluctuations. This project aims to reduce maximum temperatures and temperature variations at the module level. While heat sinks could address this, conventional aluminium heat exchangers are too costly and heavy. Additionally, as the industry shifts towards bifacial panels, opaque back-mounted solutions are incompatible with future PV technology. The solution under investigation is to create a heat exchanger design which can reduce the panel temperature while being cost effective and allowing light to the back of the panel. This work has found a natural convection correlation for turbulent conditions (1 m) for use in analytically describing cooling channel performance. This was found with experimental and simulation (CFD) methodology. This project has deployed two main categories of heatsink design in the field. A least material version and a system using more material, which have been able to decrease cell temperature by up to 5 C and 9 C in field tests of full-sized panels which cost approximately €8 and €50 per panel to modify. It is believed this can be increased further by optimizing fin length, area, and shape. More exotic fin geometries can help enhance fluid mixing and heat transfer through designs such as dimpling and twisting. These kinds of designs can disrupt boundary layers which can encourage increased fluid mixing and heat transfer. These lower temperatures would reflect a 1.5 - 2.9 % gain in output power. The following are the costs when using a 435Wp PV panel: €134,34 incl. VAT (~1.9 m2) can be used a rough guide which represent a ~6.7% increase in price (~1.5 % increased efficiency) or ~46.3% increase in price (~2.9 % increased efficiency).