Rooftop solar for all: Closing the gap between the technically possible and the achievable

Abstract

Estimating the technical potential of carbon-abatement options involves straightforward calculations, while estimating the achievable potential is more challenging. We illustrate this by examining solar photovoltaics (PV). We estimate that a 92% gap exists between the achievable and technical potential for rooftop solar in Georgia and it is shrinking slowly, while in contrast the state’s solar farms are rapidly expanding. Closing the gap between the technically possible and achievable levels of solar PV requires an understanding of why some electricity providers promote utility-scale solar and not solar rooftop systems. Our financial analysis suggests that rooftop PV on buildings in Georgia could deliver substantial economic benefits to host customers, if utilities offered favorable net metering rates and if host customers, in turn, curtailed their consumption. Comparing the slow diffusion of rooftop solar in Georgia with California and Massachusetts that are rapidly solarizing, underscores the need to develop methodologies that account for utility business models, policy interventions, and behavioral factors. A sensitivity analysis of alternative net metering policies, rebound and curtailment behaviors, a stakeholder analysis, and an assessment of barriers and accelerants documents that these factors are as important as techno-economic drivers in explaining solar technology transitions. Given the numerous barriers to adoption by low- and moderate-income households, an equitable solar transition requires business models and policies that foster participation by all.