Field thermal and energy performance of a closed-platform floating PV system on a tropical hydroelectric reservoir

Abstract

FPV systems are expected to outperform ground-mounted PV (GPV) through water cooling, unconfirmed for closed-platform FPV in tropical reservoirs, where water temperature can exceed ambient air temperature. Platform type was isolated using a co-located, identical-hardware GPV reference, monitored for 12 months at hourly resolution in a Colombian hydroelectric reservoir. The GPV system generated 1407 kWh/kWp per year, compared to 1382 kWh/kWp for the FPV system, representing a shortfall of 25 kWh/kWp (1.75%), of which 12.4% is due to resistive losses in the FPV system’s longer wiring and the remaining 87.6% to thermal loss. The FPV modules operated at higher temperatures than the GPV modules during 70.5% of the monitored hours, at a mean differential of +1.17 °C. Water beneath the platform averaged 30.98 °C, above ambient throughout. Wind speed showed no cooling effect on the temperature difference between the FPV and GPV modules (Spearman: 0.090); airflow beneath the floating platform was not measured directly, and it is possible that the irregular bathymetry (depth of 6 to 38 m) limited renewal of the surface layer. Closed-platform FPV over warm water can act as a net heat source. The 25 kWh/kWp gap equals 567 USD/year (171 kWp) or 82,725 USD/25 years (1 MW), useful for prefeasibility assessments.