Experimental and Numerical Investigation of Snow Removal From Photovoltaic Solar Panels

Abstract

A key challenge to the wide-scale implementation of photovoltaic solar panels (PV) in cold and remote areas, is dealing with the effects of snow and ice buildup on the panel surfaces. However there currently is no practical mechanism to remove snow-cover from PV surfaces and long shut-down periods occur for plant operators. The objective of this study is to evaluate different types of heating snow removal systems for PV modules and to present methodologies and tools to improve PV systems modelling and output prediction. A numerical model is presented to predict thermal snow removal from a PV panel. The model can predict snow melting or snow sliding from horizontal and inclined panels. A set of experiments was conducted using a small-scale PV panel in a freezer to provide a correlation for snow sliding from the panel. The correlation was implemented in the model to predict snow sliding situations. To validate the model and study thermal snow removal from a full scale PV panel, outdoor tests were conducted under natural conditions including different snowfall conditions. Two heating methods were investigated: embedding an electrical resistance heater to the back of the panel and imposing a reverse current through the solar cells. The results showed that ice dam and icicles formation at the bottom of the panel prevented the snow cover from sliding off the panel. In addition, the effect of heating the entire panel surface or partially heating the panel was investigated. An insulation equipped with a venting channel were proposed to use for the PV panels. This insulation improves the performance of snow removal from the panels, while having a minimum effect on the panel performance during a regular sunny day. To enhance the snow removal from the panel, the vents would be closed while opening the vents enhance the heat transfer from the panel during a sunny day. Radiation heat transfer between the panel and the insulation was also improved by coating the insulation. Outdoor tests were conducted under natural condition to study the performance of the proposed insulation during hot summer days. In terms of panel temperature and power output, the results showed promising improvement compared to using a single insulation without any modifications and especially without vents. Finally, it was proposed to remove snow from photovoltaic-thermal panels (PV/T) by circulating hot fluid through the back of a panel. Conducting outdoor tests revealed that this method can clean the panel from snow in a short period of time. The experimental results were compared with the results given by the numerical model presented in this study. To compare the required energy for snow removal with the amount of energy generated by the panel after snow removal during a day, a non-dimensional number was proposed. Using this number and conducting a case study showed that this snow removal method can be beneficial for the PV and PV/T systems.