Exploring the optimization of rooftop photovoltaic scale and spatial layout under curtailment constraints

Developing rooftop photovoltaics has become an important pathway towards carbon neutrality globally, but how to rationally implement rooftop photovoltaic development has not been investigated. This study presents a technical framework for optimizing the development scale and spatial layout of rooftop solar installations based on high-resolution generation simulation and load-oriented electricity dispatch. It is demonstrated that with the gradual expansion of rooftop development, its penetration in the electric grid grows at a decelerated speed, but the accompanying curtailment increases at an accelerated rate. Both regional sub-grid integration and improved grid flexibility marginally increase the development scale under curtailment constraint, while energy storage and trans-regional power transmission allow for significantly larger scales, thus elevating the penetration of photovoltaic generation to higher levels. The analysis reveals that the development scale should be optimized to account for regional differences in load characteristics. The optimal layout that maximizes photovoltaic penetration while minimizes photovoltaic curtailment varies with the grid flexibility and storage capacity. In China, at least 90% grid flexibility and 8-12 hours of storage capacity are required to realize 2/3 photovoltaic penetration and meet a 5% curtailment constraint. This study provides guidance for rooftop photovoltaic development in China and has implications for variable energy management in the community.