Abstract
Snow-induced photovoltaic (PV)-energy losses (snow losses) in snowy and cold locations vary up to 100% monthly and 34% annually, according to literature. Levels that illustrate the need for snow loss estimation using validated models. However, to our knowledge, all these models build on limited numbers of sites and winter seasons, and with limited climate diversity. To overcome this limitation in underlying statistics, we investigate the estimation of snow losses using a PV system’s yield data together with freely available gridded weather datasets. To develop and illustrate this approach, 263 sites in northern Sweden are studied over multiple winters. Firstly, snow-free production is approximated by identifying snow-free days and using corresponding data to infer tilt and azimuth angles and a snow-free performance model incorporating shading effects, etc. This performance model approximates snow-free monthly yields with an average hourly standard deviation of 6.9%, indicating decent agreement. Secondly, snow losses are calculated as the difference between measured and modeled yield, showing annual snow losses up to 20% and means of 1.5–6.2% for winters with data for at least 89 sites. Thirdly, two existing snow loss estimation models are compared to our calculated snow losses, with the best match showing a correlation of 0.73 and less than 1% bias for annual snow losses. Based on these results, we argue that our approach enables studying snow losses for high numbers of PV systems and winter seasons using existing datasets.
Highlights
As costs for photovoltaic (PV) modules and systems continuously drop, PV is becoming increasingly mainstream and widespread
Best data cover was gained with the snow water equivalent (SWE) product from the Cryoland service
The results show that the new approach presented in this article can be used to estimate snow losses with satisfying accuracy from just PV yield data and publicly available weather datasets
Summary
As costs for photovoltaic (PV) modules and systems continuously drop, PV is becoming increasingly mainstream and widespread. In moderate climates, significant loss levels around 5–6% typically, and up to 9.3%, have been reported, whereas plants in mild climates show typical annual losses below 2–3% [3,8,9,10]. These studies and their reported levels indicate that snow losses can have a substantial impact on the energy yield, in addition to impacting the financial conditions for the site investor and owner. Snow impacts should reasonably be taken into account during the planning of PV sites and be included in quotations and financial return on investment (ROI) or lifecycle cost of energy (LCoE) calculations
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