The challenge of removing snow downfall on photovoltaic solar cell roofs in order to maximize solar energy efficiency-Research opportunities for the future

The challenge of removing snow downfall on photovoltaic solar cell roofs, also including solar thermal panels and walls, in order to maximize the solar energy efficiency, is investigated. A special emphasis is given on possible research opportunities for the future. As the application of building integrated photovoltaic (BIPV) products is increasing, it is becoming more important to solve this challenge in order to maximize the solar energy harvesting from buildings, e.g. when attempting to reach the goals of zero energy and zero emission buildings. In addition, a solution within this field, may also be utilized in other areas, e.g. for window roofs and traffic signs which are often concealed by snow and ice. Various ideas and possible steps toward a solution of the challenge are discussed, which may then in turn set in motion creative thinking and problem solving paths with new follow-up investigations. Several aspects with snow covering solar panels are treated and discussed, including possible paths toward a working solution, where different material surface solutions like e.g. self-cleaning surfaces with origin in photocatalytic hydrophilic surfaces, superhydrophobic or ultrahydrophobic surfaces and coarse microstructured or nanostructured surfaces are reviewed and treated in particular. Furthermore, this work presents the compilation and discussion of an experimental method for measuring friction between snow/ice and various building roof surfaces. Some results from these experimental investigations are discussed, including a slip angle and a friction coefficient classification system for roofing types and material surfaces with respect to snow and ice. (C) 2013 Elsevier B.V. All rights reserved.