Modeling the Time Duration Until the Adoption of Residential Rooftop Solar Photovoltaic Systems

This paper addresses two key decisions by households to adopt rooftop solar photovoltaic (PV) systems and the length of time until the adoption. It is hypothesized that these decisions are controlled by different mechanisms and should be modeled independently. This is the first attempt to formally estimate the length of time until the adoption to the authors’ knowledge. Two models are presented in this paper. The first is a mixed logit to model the respondents’ intention to adopt a solar PV system, and the second is a random parameters ordered probit to estimate the length of time until the adoption. Estimation results show that the number of electrical appliances, the households’ interest to harness economic benefits, and the type and characteristics of the dwelling motivate households to select a shorter duration until the adoption. Results also show that the majority (77.80%) of respondents with electric vehicles are highly likely to adopt a rooftop system and select a shorter time duration until adoption. In addition, a significant proportion (83.23%) of respondents with high monthly electricity bills is more likely to adopt a rooftop PV system and select a shorter time duration. Results show that the average monthly electricity bill for households with a PV system has decreased by 74.04%. Reducing monthly electricity bills is a key instigator for adopting a rooftop PV system. Our results confirm the hypothesis that even if there is an intent to adopt a rooftop solar PV system, the length of time until the adoption is controlled by another mechanism.