Worldwide diffusion of solar photovoltaic panels and the role of state incentive: perspectives based on diffusion models

The main goal of this thesis is to use the diffusion models to improve our understanding of SPP markets, with special focus on (a) identifying the main determinants of the diffusion of solar photovoltaic panels worldwide, particularly the role played so far by public incentives, (b) characterising the scale and temporal profiles of the major domestic shocks in SPP markets which mostly occurred after 2007, (c) discussing the resulting perspectives, and the involved role of public policies, for the future development of the market. Chapter 1 is introductory and preparatory for subsequent ones and pinpoints that (a) the presence of shocks is an intrinsic and often dominating feature of energy markets, thereby motivating the use of tools as the GBM, (b) only a few countries have developed long-term energy plans towards which to manage consistently their short-medium term policies, (c) the concept of energy framework was useful to indicated a number of commonalities among countries. The main findings of Chapter 2 were the following: i) essentially everywhere the effectiveness of media communication proved negligible, ii) the early phase where the growth of the market was completely sustained by internal communication only, iii) major changes in the market adoption curves have occurred in the form of massive positive shocks which took place between 2006 and 2016 possibly following incentive measures in the various states, iv) inspection of the parameter estimates describing the temporal pattern of the shocks showed a lack of temporal persistence of the effects of incentive as well as a sharp trade-off between intensity and persistence of the actions. The results of Chapter 3 show that the SPP residential market in UK suffers not only the structural difficulties of this sector, but also the possible perception of relative penalisation suffered by late cohorts of adopters compared to the past cohorts who benefited higher rates of FIT. In the commercial and utility sectors the imitation rate is higher which might be explained by the fact that firms make more rational decisions based on economic factors rather than being led by perceptions.