The concept of spatial reliability across renewable energy systems—An application to decentralized solar PV energy

Decentralized planning of renewable energy systems aims to address the substantial spatiotemporal variability, and thus uncertainty, associated with their underlying hydrometeorological processes. For instance, solar photovoltaic (PV) energy is driven by two processes, namely solar radiation, which is the main input, and ambient temperature, with the latter affecting the panel efficiency under specific weather conditions. The objective of this work is to provide a comprehensive investigation of the role of spatial scale by assessing the theoretical advantages of the distributed production of renewable energy sources over those of centralized, in probabilistic means. Acknowledging previous efforts for the optimal spatial distribution of different power units across predetermined locations, often employing the Modern Portfolio Theory framework, this work introduces the generic concept of spatial reliability and highlights its practical use as a strategic planning tool for assessing the benefits of distributed generation at a large scale. The methodology is verified by considering the case of Greece, where PV solar energy is one of the predominant renewables. Following a Monte Carlo approach, thus randomly distributing PVs across well-distributed locations, scaling laws are derived in terms of the spatial probability of capacity factors.