Reimagining Dam Operations: An Assessment of Floating PV’s Impact on Water Management in Indonesian Multipurpose Dam.

Abstract

Floating photovoltaic (FPV) systems offer a dual advantage for water infrastructure by providing clean energy while reducing water loss through evaporation. In the context of Indonesia’s national Renewable Energy (RE) target, FPV deployment is gaining attention as a promising strategy to support sustainable energy goals. Given that most reservoirs in Indonesia are multipurpose, serving functions such as irrigation, raw water supply, flood control, and recreation, understanding the operational and environmental implications of FPV integration is becoming increasingly critical.

This study uses the Karian Dam in Banten Province as a case study to evaluate the impact of FPV at varying coverage levels. It examines how FPV affects evaporation reduction, reservoir storage performance, and water supply outcomes. The assessment is based on biweekly simulations under dry, normal, and wet hydrological conditions, complemented by an uncertainty analysis that explores the interactions between inflow variability, evaporation suppression, and reservoir characteristics.

Fully floated FPV systems reduced evaporation by up to 78%, while suspended systems achieved reductions of approximately 58%. Even partial coverage (20%–70%) produced significant water savings, especially beneficial during dry periods. These reductions directly translated into increased end-of-year reservoir storage, with high-coverage scenarios boosting dry-year storage by up to 12%. However, increased water retention in wet years can elevate the risk of High Water Level (HWL) exceedance. In the 70% coverage scenario, HWL exceedance frequency reached 13%, highlighting the need for better predictive tools, adaptive operating rules, and pre-flood release strategies. FPV-induced shading can also suppress algal blooms and may inhibit the growth of invasive floating vegetation such as water hyacinth, which reduces maintenance burdens.