Comparative Study of Snow Loss Models for PV Systems in Nordic Conditions: Townsend and Marion‐Based Approaches

ABSTRACT Snow accumulation on photovoltaic (PV) systems can cause significant energy losses, especially in high‐latitude regions. To estimate these losses with high accuracy, snow loss models have been introduced and deployed on the energy production of PV modules. This study presents a comprehensive comparison of several snow loss models, including the widely used Marion model and its recent modifications, and the Townsend model, applied to four years of PV data from a high‐latitude PV site with a harsh snowy climate. By using ERA5 reanalysis data to model baseline PV power, this research demonstrates that snow loss estimation can be achieved without site‐specific irradiance or temperature measurements. This study provides the first standardised comparison of these models under identical conditions in a Nordic climate, offering practical guidance for snow loss modelling. The models are evaluated based on annual and monthly snow losses and detailed error metrics, with the focus on winter periods. The findings highlight the potential of ERA5‐based PV simulations combined with snow models for reliable forecasting in snowy regions around the world. The results indicate that models incorporating hourly snow coverage checks and snow‐depth‐dependent clearing coefficients significantly outperform the original Marion model by reducing errors by 32%.