From Installed Renewable Capacity to Effective Renewable Integration: A Decade of Transformation in the Electrically Isolated Island Power System of Gran Canaria, 2016–2025

Electrically isolated island power systems expose the limits of renewable expansion when installed capacity growth is not matched by sufficient flexibility and absorption capability. This study examines the transformation of Gran Canaria’s power system from 2016 to 2025 using hourly demand and technology-disaggregated generation data, together with reconstructed wind and photovoltaic capacity, to assess renewable penetration, residual load, ramping requirements, and potential renewable-surplus conditions. Wind capacity increased by 306.9% and photovoltaic capacity by 489.5%, while their combined generation rose by only 178.8% under relatively stable annual demand. Between 2016 and 2025, median wind-plus-photovoltaic penetration increased from 8.6% to 26.6%, the 95th percentile from 20.5% to 49.8%, and hours above 30% penetration increased from zero to 3857 h. Over the same period, residual load at 12:00 fell from 401.8 to 267.4 MW, while the maximum upward ramp increased from 81.1 to 163.4 MW/h. Using the fifth percentile of conventional thermal generation as reference, potential renewable surplus increased from 9.0 GWh in 2016 to 255.3 GWh in 2025, accelerating markedly from 2023 onward and totaling 543.1 GWh over the decade. These results show that effective renewable integration increasingly depends on flexibility, storage, demand response, and sector coupling rather than installed capacity alone.