The surface of the vessels, as moving tiny islands, can be utilized to implement vehicle-integrated photovoltaics (VIPV). Herein, a methodology is reported to calculate the power generated by a fleet of urban vessels as a function of time. Then, the result is shown for the largest European shipping fleet, using sailing data of 2746 Dutch general cargo vessels. Results show that the studied fleet can produce ≈ 226 GWh of energy per year, which corresponds to ≈ 6.5% of the whole fleet's energy demand. Next, this research validates the model with three week experimental data gathered by a test vessel sailing through the Netherlands. The validation phase reveals that the model can predict within a 4% error range. Finally, as an interesting finding, it is experimentally shown that the energy production profile of a fleet of urban vessels follows a Weibull distribution, quantified by scale (λ) and shape (k) parameters: λ = 880 Wh Wp⁻¹ and k = 27 for the Dutch fleet. A sensitivity analysis shows that the parameters of the Weibull distribution are a function of urban fabric roughness and the climate. Such probability distribution can be extended to other urban fleets, such as solar cars, and help estimate the financial feasibility of integrating PV into vehicles.