Interactions of rooftop PV deployment with the capacity expansion of the bulk power system

Abstract

Distribution-sited solar photovoltaics (PV) economics (including rooftop PV) have improved significantly during the past several years, spurring increased installations, with over 2.2GW installed in 2014 in the United States. This increased deployment is largely projected to continue and has prompted additional interest in the interactions of rooftop PV deployment with the greater electricity system. In this paper we focus on one piece of this interface, namely the interaction between rooftop PV deployment and the evolution of the bulk power system. We develop a novel linkage between NREL’s bulk power capacity expansion model (the Renewable Energy Deployment System [ReEDS] model) and NREL’s rooftop PV adoption model (the dSolar model). We use these linked models to gain insights into the interactions of rooftop PV deployment with the bulk power system. We explore two sets of scenarios. In the first set we examine how different levels of rooftop PV deployment impact the generation mix on the bulk power system. In the second set we examine how the generation mix of the bulk power system impacts the deployment of rooftop PV by applying grid-wide curtailment rates to rooftop PV systems. In these sets of scenarios, we find that rooftop PV generation and utility PV generation have a nearly 1:1 substitution effect. We also find that curtailment rate feedback can have dramatic impacts on rooftop PV adoption, though the range of impacts is strongly dependent on the generation mix of the bulk power system and the amount of total PV generation in the system. For example, scenarios with more natural gas generation tended to have lower curtailment rates and thus more rooftop PV deployment.