On optimal PZT patch disposition for energy harvesting from statistically modelled rainfalls

We investigate rain-induced energy harvesting by exploiting the oscillatory response of piezoelectric devices in cantilever configuration subjected to raindrop impacts. The kinetic energy transferred by rainfall events is modelled basing on a statistical distribution implemented here, inspired by established formulations from meteorological literature. The coupled electromechanical governing equations of the piezoelectric energy harvester (PEH) are derived via Hamilton’s principle, modelling the system as a purely flexible Euler–Bernoulli beam. While such a model is standard in the literature, this work focuses on configurations in which the piezoelectric patches partially cover the supporting cantilever. The exact governing equations are obtained for this case, so that a subsequent configuration optimisation relevant to the rainfall distribution can be performed. The resulting system is solved numerically to capture the transient response induced by raindrop impacts. A parametric optimisation of the device geometry and patch placement is then performed, showing that, for suitable configurations, rain-induced excitation may yield energetically favourable operating conditions. These results represent a first step towards the development of small-scale piezoelectric harvesters for rainfall-driven energy conversion.