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New energies 25/11/2020

Solar On Water: A Bright Future For Floatovoltaics

Growth forecast for floating photovoltaic (FPV) and the efficiency of this energy source make it very attractive but are there only benefits?

In the coming years as more large-scale floating farms are coming online around the world and research projects are being launched, here’s what we know today about the pros and cons of floatovoltaics

In 2008, the first commercial floating photovoltaic (PV) system went operational at a California vineyard. The goal was simple: to avoid digging up valuable vines by installing solar panels on an irrigation pond. Twelve years later, FPV — or, “floatovoltaics” — may still be considered a niche market, but is in full growth mode. Over the next five years, FPV’s are forecast to expand more than 20%.

So far, growth has mostly been driven by geographical considerations as FPV offers a way to ramp up solar power in countries with land scarcity that have sufficient bodies of water. For example, South Korea — where 70% of the land is covered by mountains — has been earmarked as the site for the world’s largest FPV installation coming online in 2025. 

But some of FPV’s benefits are still debated, especially in areas where longer-term research is still lacking. While we’ll learn a lot more in the coming years as more large-scale floating farms are coming online around the world and research projects are being launched, here’s what we know today about the pros and cons of floatovoltaics;

THE BENEFITS 


  • Reduced land impact Solar panels mounted on pontoons, on lakes or at sea, have no support foundation and don’t require excavation for the panel or cable. This also makes for reduced installation time.
  • Natural cooling system Due to the cooling effect of the water, a PVS system can reach a higher efficiency than its ground-mounted counterpart. While the level of added yield varies depending on season, water temperature and design, studies suggest that an FPV generates between 10% and 15% more power than a standard panel in the same area during summer. 
  • Waste usage Floatovoltaics can make use of otherwise idle wastewater bodies such as polluted industrial ponds. One such example can be found in China where a flooded area once used for coal mining has been turned into a floating solar farm. The 70-MW project covers 63 hectares and generates enough electricity to power 21,000 homes. 
  • Reduced evaporation Especially in countries where water resources are limited, an added benefit is the reduced surface area of the reservoir which limits heating and evaporation [1] . Some studies have suggested that FPVs can reduce water evaporation by up to 33% on natural lakes and ponds. 
  • Less algae photosynthesis allows for the growth of algae that often obstructs pumping and filtration systems. Floatovoltaics shades the water which reduces formation of algal blooms and thereby the need for recurring chemical treatments. 


THE CHALLENGES 


  • Ecosystem risks Despite some proven short-term benefits, we still don’t know enough about the longer-term impacts on marine environments. For example, algae may disrupt pumping systems, but reduced photosynthesis  [2]  could also alter the natural ecosystem of water bodies by killing organisms that provide valuable nutrients such as nitrogen compounds and other hydrocarbons  [3]. Shading and sediment resuspension are of particular concern for coral reefs and seagrass  [4]. The whole biodiversity of the aquatic system is likely to get affected.
  • Disrupted fishing More broadly, large-scale FPV installations could have a negative socioeconomic impact by impairing both fishing and navigation. While in the future, panels could be designed with gaps to let through light, or movable panels to avoid permanent sunblock, more research is needed to find the right solutions. 
  • Regulatory hurdles In most countries, regulation to license the construction and operation of renewable energy plants isn’t tailored to floating installations which can cause costly delays in the installation process. Water bodies are also subject to high scrutiny from authorities, and sometimes have complex regulatory frameworks of their own. Developers may also be required to regularly conduct comprehensive environmental impact assessments. 
  • Young technology Above all, what keeps Floatovoltaics a niche market is the lack of robust data on what is still a nascent technology. Compounding the potential long-term environmental issues are unanswered questions about economic viability and efficient deployment in more challenging locations, such as areas with heavy snowfalls or frequent storms. While large-scale projects have already proven commercially viable in some environments, we are still learning about the technical complexity — such as safety, mooring and maintenance — of designing and operating on water. 


[1] da Silva, G.D.P., Branco, D.A.C., 2018. Is floating photovoltaic better than conventional photovoltaic? Assessing environmental impacts.

[2] Sahu, A., Yadav, N., Sudhakar, K., 2016. Floating photovoltaic power plant: a review.
[3] Alona Armstrong, Trevor Page, Stephen J. Thackeray, Rebecca R. Hernandez & Ian D. Jones, 2020. Integrating environmental understanding into freshwater floatovoltaic deployment using an effects hierarchy and decision trees.
[4] Benham, C.F., Beavis, S.G., Hendry, R.A., Jackson, E.L., 2016. Growth effects of shading and sedimentation in two tropical seagrass species: implications for port management and impact assessment. 


RESEARCH & INNOVATION 


  • DIY Floatovoltaics A U.S.-Finnish research team has developed a way to adapt commercially available thin-film solar panels to floating projects. The special panel design, which can be applied to three different types of floating materials, is an open-source, after-market technique that would allow consumers to build their own Floatovoltaics. This might prove a good solution for summer home owners who can easily pull the system out of the water for the winter. 


  • Storm proofing In the Port of Rotterdam, two Dutch companies have finalized a three-year storm-testing pilot system for floating PV. The PVs — floating on a contaminated water basin — managed to sustain four severe storms throughout the testing period — one of which recorded wind gusts of 144 km/h. 




  • Durable design With the construction of a small FPV on a hydroelectric plant reservoir, Lithuanian company Ignitis Gamyba aims to overcome two technical hurdles. Firs, the design must be able to sustain the changing water levels — up to 10 metres when the hydropower plant is operating at full capacity — and secondly, the mooring and other equipment must be adapted to the reservoir freezing over during winters. The first stage of the 200-MW project is scheduled for completion by the end of 2021. 




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