Comment: 23 pages, 6 figures, 1 table, under review by Technological Forecasting and Social ChangeThe 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.