In this paper, a polynomial model is developed for determining the winter season optimal tilt angle for fixed-tilt PV installations in Uyo metropolis, Akwa state of Nigeria. Satellite-derived NASA SSE solar radiation data was used in the study and the simulation was done using PVSyst software. The polynomial model is given as WTF(β)= -0.00013(β^2 ) + 0.00643(β) + 0.99991; where WTF(β) is the winter average transposition factor and β is the tilt angle in degrees. The model has prediction accuracy of 99.92% with root mean square error of 0.001267 and optimal winter season tilt angle of 24.73°. Furthermore, the study also did the comparison of the effect of using seasonal or yearly fixed tilt and seasonally adjusted tilt angle for the PV panel. The results show that the greatest yearly average transposition factor is obtained when the tilt angle is optimally adjusted to suit the Winter months during the Winter and to suit the Summer months during the Summer seasons.