SPECIAL POLICY BRIEF: New Options for Meeting Growing Energy Needs

One of the most exciting recent developments in solar power is the emergence of floating solar technology – the construction of photovoltaic (PV) arrays that float on top of a body of water. This technology, also known as ‘floatovoltaics,’ is still in a relatively early stage of development, but offers numerous advantages for countries across the Caspian region.

First, floating solar can be paired with pre-existing hydropower capacity by installing arrays on the accompanying reservoir. This arrangement eliminates the need to install long power transmission lines to new solar plants, since the neighboring hydroelectric station is already integrated into the grid. Furthermore, the pairing of floatovoltaics and hydro addresses the base-load problem for solar, since the production of hydropower can be adjusted based upon current output from the solar arrays. Thus, water is run through the system when the arrays are not producing but outflows are curtailed when the sun is shining, allowing the pair to generate consistent volumes of electricity regardless of the weather. Absent significant hydropower capacity, the variable output of solar power plants means there is a need for energy storage technologies or natural gas “peaker plants” which entail additional investment. Pairing solar and hydro generates more consistent power output that helps avoid these costs.

Second, proximity to the surface of the water boosts the system’s operational efficiency by modulating the temperature of the solar array. This is significant because, paradoxically, solar panel efficiency drops as temperatures increase. Thus, the water’s regulatory effect upon the temperature of the panels raises the power output of solar arrays. The efficiency gains attributable to temperature regulation depend on climatic conditions, with hot locations seeing the biggest improvement. A recent World Bank report on floating solar suggests that efficiency gains could be “conservatively estimated at 5 percent, but potentially as high as 10-15 percent in hot climates.”

Third, floating solar avoids the need to procure large areas of cleared land. The benefits of this feature are particularly pronounced for mountainous countries, which often lack large supplies of flat, sparsely populated territory suitable for solar power installations. While solar panels can be installed on inclined sites, this situation is not ideal. Panels located on a slope receive less sunlight throughout the course of the day, reducing electricity output.

Moreover, building on uneven terrain can substantially increase the cost of preparing the ground and installing mounts for solar panels. This has been a reason why mountainous Japan has been deeply involved in the development of floating solar, hosting the first floating PV installation, built in 2007 in Aichi. Japan also holds the distinction of having around 80 percent of all functioning floating solar installations, though admittedly many of these projects are small in scale.

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