Drivers and diusion of residential photovoltaics in France

摘要

This paper analyses the diffusion of residential solar panels, and the impact of financial incentives (feed-in tariffs and local subsidies) on this dynamics. We use a unique database provided by Enedis, the main French DSO, giving the quarterly number of connection requests for 33,842 municipalities, from the end of 2008 to mid-2016. Using solar irradiance, panel system costs, and national and local subsidies, we compute an internal rate of return per municipality and per quarter. Due to the high number of zero-installation data points, we use a two-stage ("hurdle") specification. We first model the probability of having at least one installation, and then the (strictly positive) number of installations, the vast majority of which are 3-kW panels. Controlling for individual characteristics of the municipalities, we find that the financial incentives have a positive and significant effect on both the probability and the number of adoptions. Furthermore, we show that the diffusion process exhibits "epidemic" and "stock" effects, which are consistent with the "S"-shaped diffusion curve observed at the national and regional levels. In particular, an additional past installation in a city has the same effect as a one-point increase of the IRR: an increase of the odds of installing at least one solar panel by roughly 10%. This could help promote renewables at a lower cost for example through more information and local funding of PV projects.