Resumen: In recent years, new materials and absorber configurations have been proposed to improve the performance of hybrid photovoltaic-thermal (PV-T) collectors. This work analyses the fluid flow and the energy performance of an uncovered water-based PV-T collector with a roll-bond thermal absorber. A detailed CFD model was developed and the results were compared with the experimental performance features provided by the PV-T manufacturer. The fluid flow results show uneven flow distribution among the roll-bond microchannels which leads to areas with larger PV cell temperatures and thus a lower electricity generation. The PV-T collector layers were also modelled using the energy transfer equations layer-by-layer. The model was run for several water inlet temperatures and water flow-rates to obtain the thermal performance curve. The results show that the electrical efficiency of the PV-T collector is 14.5–10.3% larger than for a PV-only system for water inlet temperatures of 20–30 °C, respectively. The developed CFD model reproduces accurately the thermal performance of the PV-T collector, with a maximum error of 6.5% for inlet water temperatures of 20–60 °C. Therefore, this model can be used with confidence to propose alternative designs that achieve a homogeneous temperature distribution in the PV layer and improve the overall PV-T collector performance. Idioma: Inglés DOI: 10.1016/j.renene.2023.03.125 Año: 2023 Publicado en: Renewable Energy 209 (2023), 122-132 ISSN: 0960-1481 Factor impacto JCR: 9.0 (2023) Categ. JCR: GREEN & SUSTAINABLE SCIENCE & TECHNOLOGY rank: 16 / 91 = 0.176 (2023) - Q1 - T1 Categ. JCR: ENERGY & FUELS rank: 24 / 171 = 0.14 (2023) - Q1 - T1 Factor impacto CITESCORE: 18.4 - Renewable Energy, Sustainability and the Environment (Q1)