In this paper, thermal modeling of a hybrid photovoltaic/thermal (PV/T) system has been developed under combined (front and back) water surface cooling. An analytical expression has been derived for solar cell temperature (T-cs), back surface temperature (T-bs), and overall efficiency (eta(OE)) of the hybrid PV/T system for the winter condition. Statistical analysis has been performed in the cold climate of MNIT, Jaipur (India), for determining performance parameters of the hybrid PV/T system. An experimental validation has been carried out for the developed thermal model, and fair agreement between the numerical and experimental observations has been observed. We have also calculated the electrical (eta(ele)), thermal (eta(th)), and overall efficiency (eta(OE)) as 18.83%, 43.8%, and 64.56%, respectively, and output power as 57.39 mW in the winter condition. We have also noticed that better performance is given by 1.5 LPM out of the four (1, 1.5, 2, and 2.5 LPM) flow rates.