What Are Floating Solar Panels, and Can They Work?
Ground mounted solar PV and rooftops with solar panels are becoming ubiquitous. Now, imagine solar panels floating on water. Floating solar (or floating photovoltaic, FPV) is an emerging trend, and may become a relevant part of the technical toolbox for addressing climate change. The first FPV installation was commissioned in 2017 and, according to the International Finance Corporation, more than 300 floating solar parks were installed worldwide in 2020. The total installed capacity was estimated at 1.5GW at the end of 2019 and is predicted to reach 4.6GW by 2022.
How does it work?
The electrical configuration of a floating PV system is similar to the land-based PV system. The concept requires attention to many elements, as the installation of course involves the combination of electricity and water. In essence, solar panels are attached to a series of interconnected plastic rafts and the whole system is securely anchored to the bottom of the body of water. Because of this, they are usually located in calm waters such as ponds, lakes or man-made reservoirs, with floating walkways provided to enable access for any maintenance or servicing work. The solar electricity generated is transferred to a central inverter before reaching electrical equipment onshore via underwater cables. The inverter is used to convert the direct current (DC) produced by the solar panels into alternating current (AC) needed to power electrical devices through the power grid.
Floating solar can also be installed on the reservoirs created by dams. Transmissions systems already available in hydropower facilities can be used to store and distribute the electricity produced by the floating PV. The latter is floating next to the dam and can complement the hydropower plant since solar power has the most potential during dry seasons, while rainy seasons are more suitable for hydropower. Floating solar could therefore significantly increase the capacity of large hydropower plants while covering only 3 to 4% of the reservoir. Hydro plants reservoirs cover more than 250,000 km2 worldwide, meaning ample opportunity for floating solar. The area would in fact be enough to host sufficient floating solar capacity to generate 2.5 times the electricity produced by all the underlying hydropower.
FPV plus bifacial panels
Solar energy is a booming market. More and more innovations are developing and challenging previously dominant technologies. Bifacial solar panels are one of many examples that are becoming increasingly popular as the cost of solar cells continues to fall.
Bifacial solar panels are similar to traditional solar panels except they have their backsides covered with either transparent sheeting or a double glass panel, which makes it so that they can produce energy from both sides, increasing the total electricity output. These bifacial solar PVs are now being tested on water too. Bifacial modules in floating PV applications have been modeled by scientists led by the University of Ontario, and their findings suggest that the module could receive 55% more sunlight than a monofacial floating module. While other factors need to be taken into consideration, such as wind, the potential advantages are promising.
The Asia-Pacific region currently accounts for 87% of the global floating solar capacity. The rest of the world accounts for an estimated 350 operational floating PV systems, spread across more than 35 countries. The first installations were introduced in Japan in 2017. Since then, Japan has commissioned some 180 MW of floating solar projects. Korea, the United Kingdom and China – which has the largest number of plants installed – have been closely following the footsteps of Japan. Other Asian countries such as Bangladesh, Laos and Indonesia have also announced larger floating solar projects.
India is targeting 2022-23 to begin operating the world’s largest floating solar project, which is expected to overtake China. The floating panels will cover approximately 2,000 ha of water with a capacity of 600 MW. In Europe, the largest floating solar array is located in France. Installed in a lake in 2019, it produces enough power to meet the demand of over 4,700 homes.
Companies like Equinor (EQNR) – an oil and gas giant – are focusing R&D capital towards further innovations. Alongside with Moss Maritime, Equinor announced a new research project: the first floating solar pilot plant in rough water. The project construction is planned to start in late summer 2021 in Western Norway. The company is also currently testing other floating solar projects in Sri Lanka and the Netherlands to address, respectively, how to increase energy productivity and test the resilience of production under harsher conditions.
What makes floating solar promising?
This innovation is starting to attract global attention, because it has several advantages that could compete with more traditional solar installations. First, it has broader environmental benefits, as there is no loss of valuable land space. It also avoids vegetation and tree clearing sometimes required for larger installations. This is the reason why floating panels have been tested in countries currently coping with a lack of available arable land like China or Japan.
Second, its performance is 5 to 10% higher than ground-based solar arrays. Water and wind can help to cool the solar cells, improving their efficiency and productivity. The panels can also help to limit water evaporation during periods of drought and hinder the production of algae which threatens the quality of the water, especially in freshwater basins. Finally, the most obvious benefit is that the installations are a source of clean, renewable electricity that will help reduce greenhouse gas emissions.
As of now, engineering and construction costs are higher than land-based solutions due to specialized equipment needs, although the cost is expected to reduce with further developments and technologies. The majority of floating solar arrays are also bigger in scale, making them appropriate for municipalities, communities and companies but not suitable for individual households.
Despite these challenges, floating solar is showing promising growth, and could become one of the most exciting low carbon innovations around the world.
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