  The paper uses diffusion models to understand the main determinants of
diffusion of solar photovoltaic panels (SPP) worldwide, focusing on the role of
public incentives. We applied the generalized Bass model (GBM) to adoption data
of 26 countries between 1992-2016. The SPP market appears as a frail and
complicate one, lacking public media support. Even the major shocks in adoption
curves, following state incentive implemented after 2006, failed to go beyond
short-term effects and therefore were unable to provide sustained momentum to
the market. This suggests that further barriers to adoption should be removed.
