Resumen: The optimization of polygeneration systems considering hourly periods throughout one year is a computationally demanding task, and, therefore, methods for the selection of representative days are employed to reproduce reasonably the entire year. However, the suitability of a method strongly depends on the variability of the time series involved in the system. This work compares the methods Averaging, k-Medoids and OPT for the selection of representative days by carrying out the optimization of grid-connected and standalone polygeneration systems for a building in two different locations. The suitability of the representative days obtained with each method were assessed regarding the optimization of the polygeneration systems. Sizing errors under 5% were achieved by using 14 representative days, and the computational time, with respect to the entire year data, was reduced from hours to a few seconds. The results demonstrated that the Averaging method is suitable when there is low variability in the time series data; but, when the time series presents high stochastic variability (e.g., consideration of wind energy), the OPT method presented better performance. Also, a new method has been developed for the selection of representative days by combining the k-Medoids and OPT methods, although its implementation requires additional computational effort. Idioma: Inglés DOI: 10.1016/j.renene.2019.11.048 Año: 2020 Publicado en: Renewable Energy 151 (2020), 488-502 ISSN: 0960-1481 Factor impacto JCR: 8.001 (2020) Categ. JCR: GREEN & SUSTAINABLE SCIENCE & TECHNOLOGY rank: 7 / 44 = 0.159 (2020) - Q1 - T1 Categ. JCR: ENERGY & FUELS rank: 16 / 114 = 0.14 (2020) - Q1 - T1 Factor impacto SCIMAGO: 1.825 - Renewable Energy, Sustainability and the Environment (Q1)