A new detailed transient model for PVT-water collectors is presented. The model uses a nodal approach based on the electrical thermal analogy using RC networks to model the thermal response of the PVT collector. Unlike models found in the literature, the RC network is directly used to simulate the PVT collector in an electronic circuit simulator. Heat flow is modelled in one dimension only and average temperatures are used for the fluid and absorber plate in order to calculate the transient thermal output of the collector. A discussion on the correct calculation of the average temperatures for the collector and possible approximations is presented. The model was used to simulate a PVT collector coupled to a domestic hot water load, in order to study the daily performance of a PVT-water system and its transient behaviour. Results show that the proposed solution can achieve extremely good agreement with experimental data, and that the model could be used for performance analysis and product design. (C) 2015 Elsevier Ltd. All rights reserved.