Long-Term Solar Resource Variability and Its Implications for Grid-Scale PV Plant Energy Yield Uncertainty in Nigeria: A Stochastic Climatological Investigation

This research conducts a stochastic climatological investigation of long-term solar resource variability across Nigeria and quantifies its implications for energy yield uncertainty in grid-scale photovoltaic power plants, providing original contributions to the bankable solar resource assessment science required to underpin renewable energy investment decisions in the Nigerian market. Nigeria's PV investment pipeline is increasingly attracting international capital, and project finance lenders require robust quantification of solar resource uncertainty across the plant lifetime to assess debt service coverage risk. However, existing solar resource assessment practices in Nigeria rely predominantly on satellite-derived irradiance datasets covering 10 to 22 years, which is insufficient to characterise multi-decadal climate variability cycles that affect long-term PV energy yield. This research develops an original statistical framework combining paleoclimatic proxy reconstructions, historical rainfall teleconnection analysis, and long-range climate model ensemble outputs to extend the effective solar resource record for Nigerian sites to 100 years, enabling robust extreme value statistics and P90 energy yield exceedance probability calculations that account for inter-decadal variability. The methodology is applied at eight candidate utility-scale PV plant sites distributed across all six geopolitical zones, covering the diverse climate regimes from the Sahel to the Niger Delta. Original contributions include derivation of a Nigeria-specific solar resource variability index that condenses multi-dimensional climate uncertainty into a single bankability risk parameter, and a Monte Carlo simulation engine that propagates resource uncertainty through a full PV plant performance model to produce probabilistic annual energy production estimates. Keywords: solar resource assessment, variability, energy yield uncertainty, grid-scale PV, Nigeria.