Floating solar cost-competitive with ground-mounted PV in southern Europe


Researchers from Italy and Spain have estimated the energy yield and cost potential of floating PV (FPV) across suitable bodies of water in Europe and have compared them to optimally tilted, land-based photovoltaics (LPV).

“We also show that in Mediterranean countries, FPV can already economically compete with traditional LPV, because of the sun’s higher position and the higher temperatures in these locations,” researcher Leonardo Micheli told pv magazine. “However, FPV becomes cost competitive in all the modeled scenarios and countries if capital costs are reduced by less than 12%.”

The scientists estimated Europe's potential FPV capacity by using the water surface data available for Europe in the Global Reservoir and Dam Database (GRanD). They only considered reservoirs used for hydroelectricity, water supplies, irrigation, and flood control. They simulated the energy yields of monofacial modules by using the PVWatts DC power model, with data on hourly irradiance from CAMS Radiation Service.

For the FPV applications, the model considered scenarios with 10-degree and 20-degree tilt angles and an albedo of 0.06. The tilt angle on LPV was assumed to be optimal, and the albedo 0.25. Both simulations used Trina Solar modules with 21.4% efficiency, inverters with an efficiency of 96%, and DC to AC losses of 14%. All modules were south oriented, and the PV system lifetime was set at 25 years. The scientists sourced data from the IRENA Renewable Cost Database to calculate the capex and yearly operation and maintenance expenditure (omex) for different locations across Europe.

The study looked at the performance of FPV and LPV in four thermal scenarios. The results showed that FPV systems can produce a yield of between 640 and 1688 kWh/kW/year, corresponding to capacity factors of 7.3% to 19.3%.

“The higher yields are found, unexpectedly, in the Southernmost countries, where the solar potential is higher and the angular and reflection losses due to the lower tilt angles are limited,” the researchers said.

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The worst performances are found in the Scandinavia and the alpine regions of Switzerland, Austria, and Italy. In the most optimistic thermal exchange scenario, FPV electrical performance is highest and returns yields up to 2% higher than LPV.

“In this scenario, 20-degree tilt FPV grants higher yields than optimally tilted LPV in several countries. In other configurations and scenarios, however, the yields of FPV are typically lower than those of LPV, especially at 10- degree tilt,” the researchers said. “These results highlight that the effect of the tilt angles on the energy conversion is significant.”

The study estimates that each additional degree of tilt angle in FPV installations is worth between €2.50 ($2.62)/kW and €7.50/kW.

Given these differences in energy yield, FPV's competitiveness on levelized cost of energy (LCOE) depends on allowances for capex and omex. In general, results show that LPV’s LCOE would be competitive in most European countries across all scenarios if racking and mounting costs are eliminated. If grid-connection costs are also eliminated – for example, via the hybridization with hydropower – FPV could be cost-competitive in all countries, in all modeled scenarios.

The research group shared its findings in “Techno-economic potential and perspectives of floating photovoltaics in Europe,” which was recently published in Solar Energy. The group includes researchers from the University of Jaén in Spain and the University of Catania in Italy.

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