A flexible, flag-like wind energy harvester made from metallized PVDF material is introduced. A mathematical model for the piezoelectric flag excited by wind flow is developed. The model is validated with experimental results. The flag is modeled as an Euler-Bernoulli beam with a low bending rigidity. The wind excitation is modeled using the slender-wing theory. Among other modeling assumptions, the partial differential equation is considered separable and is subjected to two different sets of boundary conditions that are applied to find the mode shapes of the system. The temporal relationship for the electromechanical system is normalized with the resultant eigenfunction. The experimental investigations are performed with longitudinal flow along a PVDF flag in a wind tunnel. Experimental and analytical results match and represent the periodic system response of voltage, power and displacement over time. The two sets of boundary conditions applied to the model provide an envelope for predicting the outputs of the system. Results show that for both sets of boundary conditions, the frequency of the system has a nearly linear relationship to the wind velocity.