Snow adhesion mitigation on building integrated photovoltaics
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Solar energy is one of the main environmentally responsible forms of energy production and one that is very interesting for private citizens to invest in. The cost for private citizens to invest in solar energy, however, has still not reached parity with fossil fuels such as natural gas. Integration of photovoltaic cells in building skin elements such as roofing or wall cladding, however, makes it possible to co-invest in both simultaneously. This may allow for a dramatic energy price reduction while maintaining the original aesthetics of the architecture. In the cold regions of the world, where snow and ice are common occurrences, these present another challenge by accreting on the solar panels. The winter months, when snow and ice is most prevalent, is also the time when the energy is most needed. Though it is the least productive time of the year, between 1-20% of the annual production may be lost due to accumulation of ice and snow covering the solar panels. Based on a thorough state-of-the-art analysis, resulting in two review articles, it was determined that snow adhesion differs fundamentally from ice adhesion. Snow adhesion is a less explored area, often conflated with ice adhesion. The scope of this thesis was therefore narrowed from including both ice and snow adhesion mitigation, to focus specifically the mitigation of snow adhesion. In order to explicitly test the similarities and differences between ice adhesion and snow adhesion, a controlled method for snow adhesion measurement was developed. This method was then applied to known ice adhesion mitigating surfaces to ascertain the extent of the difference in behavioural trends. It was found that the level of ice adhesion mitigation has no apparent bearing on the level of snow adhesion. The method was further applied to glass surfaces of varying roughness to begin the process of accumulating quantitative adhesion data specific to snow, and to test the limitations of the method. Results indicate that increased surface roughness on glass in the micrometre scale will have a drastic negative impact on snow adhesion mitigating efforts. All analyses of snow adhesion were performed using synthetic snow. The use of synthetic snow allows for repeated production of snow with identical properties, something that cannot be attained with in-situ measurements using natural snow. This ensures the reproducibility of the experiments such that results may be independently verified. After having determined that snow adhesion should indeed be studied separately from ice adhesion, a suggestion for a redefined terminology was presented, along with a framework for classification of performance.
Består avPaper 1: Passive Snow Repulsion: A State-of the-art Review Illuminating Research Gaps and Possibilities. https://doi.org/10.1016/j.egypro.2017.09.650 Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Paper 2: Borrebæk, Per-Olof; Jelle, Bjørn Petter; Zhang, Zhiliang. Avoiding snow and ice accretion on building integrated photovoltaics - challenges, strategies, and opportunities. Solar Energy Materials and Solar Cells 2020 ;Volum 206. s. 1-12 https://doi.org/10.1016/j.solmat.2019.110306
Paper 3: Borrebæk, Per-Olof; Jelle, Bjørn Petter; Klein-Paste, Alex; Zhang, Zhiliang; Selj, Josefine; Marstein, Erik Stensrud. A Gravity-based Method for Measuring Snow Adhesion
Paper 4: Borrebæk, Per-Olof A.; Rønneberg, Sigrid; Li Tong; Jelle, Bjørn Petter; Klein-Paste, Alex; Zhang, Zhiliang. Snow adhesion on icephobic surfaces
Paper 5: Borrebæk, Per-Olof A.; Jelle, Bjørn Petter; Klein-Paste, Alex; Zhang, Zhiliang. Influence of glass surface roughness in the microstructure range on snow adhesion.
Paper 6: Borrebæk, Per-Olof; Rønneberg, Sigrid; Jelle, Bjørn Petter; Klein-Paste, Alex; Zhang, Zhiliang; He,Jianying. A framework for classification of snow- and icephobicity.