Techno-economic assessment of integrated floating photovoltaic and small-scale pumped hydro storage systems: A case study of the Te Mārua reservoirs in Wellington

Abstract

The integration of floating photovoltaic (FPV) and pumped hydro storage (PHS) systems offers a promising hybrid renewable energy solution, particularly when co-located on water reservoirs. This study investigates the technical, economic, and environmental feasibility of deploying a 10 MW FPV array with a small-scale 10 MW PHS system at the Te Mārua reservoirs in Wellington, Aotearoa New Zealand. Using a multidisciplinary techno-economic framework, the analysis combined site-specific solar and hydrological data, system modelling, simulation, and financial assessment over a 60-year horizon. The results indicate annual FPV generation of 14.4 GWh and PHS storage of 100 MWh per cycle, with complementary seasonal profiles enhancing grid stability and renewable dispatch. Financial metrics show FPV offers low Levelised Cost of Energy (NZ$150/MWh) and short payback, while PHS delivers a higher Net Present Value (NZ$47.7 million) through energy arbitrage. Environmental and social considerations are addressed through conservative array coverage and stakeholder engagement. The study provides a replicable framework for hybrid FPV-PHS deployment on similar reservoirs, supporting energy resilience and decarbonisation objectives.