The objective of this study is to estimate the yearly thermal and electrical enhancement of a hybrid PV operating with nanofluids. The examined nanofluid is Cu/water and it is compared with water as working fluid for various operating conditions. An integrated solar thermal system with a hybrid PV and a storage tank is examined for twelve typical days in order its yearly performance to be determined. Different storage tank volumes are investigated because of the storage capacity influence on the thermal and the exergetic performance of the system. According to the final results, the storage tank of 150 L is found to be the most suitable solution for the hybrid PV of 2 m(2) collecting area, using exergetic criteria. For this case, the yearly thermal performance enhancement is about 4.35%, while the electrical and exergetic enhancements are 1.49% and 3.19% respectively. Moreover, it is found that the yearly enhancement is higher in the cases with greater storage tanks. The study is performed with a developed thermal model in EES (Engineering Equation Solver) which is validated with experimental literature results. The climate data has been taken from the literature for Athens, Greece. (C) 2017 Elsevier Ltd. All rights reserved.