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Floating the idea of solar on the sea

September 23, 2024

Ocean-based floating solar PV systems present vast potential for untapped renewable energy growth, but research into marine environment deployment shows gaps and challenges in developing this nascent resource. Compiled by Theresa Smith.

Floating solar photovoltaic systems (FPV) are gaining traction thanks to their potential for higher energy yield and efficiency compared to conventional land-based solar PV systems.

FPV contributes to the efficiency gains of a power plant, because of the natural cooling effect provided by the proximity of water associated with the reflectivity of water increasing the irradiance of the PV array. Additionally, they can help reduce water evaporation by providing shading to the water underneath.

A recent study, Towards sustainable power generation: Recent advancements in floating photovoltaic technologies, found that there are significant gaps in knowledge and information in the technology and it examines some of the research and development that has been reported.

A critical review of a vailable information indicates that advances in this technology should focus on improving floating structure design, robust instrumentation, wireless monitoring and sensing capabilities.

Novel technology solutions such as programming algorithms for grid integration and artificial intelligence should also be explored.

Despite advances, hurdles remain and these must be addressed to leverage the technological innovations that can help the world transition towards sustainable energy production.

FPV gaining traction slowly

Worldwide installed capacity of FPV power plants reached more than 3GW in 2021, from just 100MW in 2016.

Projections indicate an expected growth rate of 22.5% by 2030.

Not all geographic conditions are suitable for FPV, but a very promising location is a hydropower dam. Integrating FPV on hydropower dams maximises RE generation while it capitalises on existing infrastructure, potentially revolutionising the energy landscape.

“Structural challenges regarding the durability of FPV systems in diverse water bodies need more investigation.”

While RE consumption is high in European countries, China has taken the lead in FPV energy production with a 320MW FPV plant in operation since 2021.

Singapore also installed a 60MW FPV plant in 2021 and east from there FPV is emerging as a valuable energy source for diverse communities with successful implementation in the fishing community that resides in Mainit Lake in the Phillipines. This community-specific application highlights FPV’s adaptability and effectiveness in addressing singular energy needs.

Recent policies favouring RE installations in Southeast Asia, coupled with growing environmental awareness, have boosted FPV system installation with continued growth expected in the near future.

Floating solar closer to home

A case study on six hydropower dams in Zambia that uses SAM software, says projects that cover just 10% of the country’s hydropower reservoirs with FPV, could increase present installed capacity of power generators by eightfold.

Historical data suggests that a hybrid system of FPV and wind power at the Kainji hydropower station in Nigeria could have produced a maximum combined power output of 608MW to 1,447MW between 2016 and 2019. FPV could offer an attractive solution to land acquisition challenges in Nigeria and make it a viable option for expanding RE infrastructure.

Studies also indicate that FPV systems have the potential to mitigate water evaporation, with an estimated 80% reduction in evaporation posited for South Africa’s Nqweba Dam. The City of Cape Town started a pilot in 2021 for a FPV system at a wastewater treatment plant to determine evaporation savings and relative energy generation performance.

As ESI Africa reported, KenGen at the beginning of 2024 issued an expression of interest for a feasibility study into FPV on the Kamburu Hydropower Plant Reservoir for a 40-MWp system in Kenya.

The Central Electricity Board of Mauritius in early 2023 invited bids for the design, supply, installation, testing and commissioning of a 2MWac floating solar power plant at Tamarind Falls Reservoir.

In April 2023, an IPP signed a PPA to construct a 5.8MWp floating solar plant to supply renewable energy to the Seychelles grid and the first ever FPV plant in the MENA region went live in mid-June 2022 – the 200kWp FPV plant on Lac 3 in Tunisia.

Ghana successfully inaugurated the Bui Hydro-Solar PV Hybrid (HSH) system at The Bui Generating Station with a 5MW FPV system that went online in 2021. The 404MW hydropower station is complemented by a 50-MWp groundmounted solar PV system, the FPV and a 20MWh battery energy storage system.

The dual benefit of electricity generation and water conservation positions FPV as a promising solution for African countries facing energy and water scarcity concerns. As such, FPV technology has also been proposed as an effective solution for address water crises in Egypt.

An MDPI report – Global Atlas of Marine Floating Solar PV Potential – shows FPV is viable in regions which rarely experience waves larger than six metres or winds stronger than 15m/s. FPV systems are extremely viable. This means there could be potential for FPV systems in the calm tropical maritime regions, specifically off the coast of West Africa.

Marine-based FPV

While adverse effects of FPV in inland water bodies need a thorough examination, exploration of FPV feasibility in marine environments has already begun. In late 2022, China installed a pilot-scale two-floater 0.5MWp marine FPV system in the Yellow Sea, outside Shandong, which integrates FPV with offshore wind.

But deploying FPV systems in marine environments presents unique challenges that include harsh waves, strong winds and the corrosive nature of seawater, among others.

Different technologies are being investigated to address these challenges such as pontoon-type floats made of HDPE material, fiber reinforced plastics, overcoatings and encapsulations for FPV in the marine environment.

Adaptive mooring and anchoring techniques similar to what ships use for FPV systems, have also been suggested. Other strategies include column-stabilised systems, while several researchers argue that pontoon structures are unsuitable for the environment and instead propose the use of thin film solar PV.

Research into low-weight, soft and circular, particularly submerged floats for FPV systems have demonstrated good performance against harsh waves which exceed 10 metres high. Further research is underway to develop stable structures tailored specifically for FPV deployment in marine environments.

Challenges and the way forward for floating solar

Lack of established policies, incentives and subsidies to support FPV development is a significant barrier. There is also the need for standardisation in the installation procedures and requirement guidelines for FPV technology.

Combining water and electricity presents safety risks tha t must be carefully addressed and installation and maintenance of transmission infrastructure near water bodies call for heightened vigilance.

Structural challenges regarding the durability of FPV systems in diverse water bodies need more investigation with concerns that include degradation, corrosion, friction and stress on moving parts. All these may lead to catastrophic failure, especially during weather-related events such as floods. The safety of large floating structures is of great concern as high wind forces could collapse the floating structures.

Also, the effectiveness of mooring and anchoring systems varies with water levels, which calls for a comprehensive understanding of water body topography and the suitability of anchorage for floats. Inappropriate tilt angles of existing solar panels currently on the market make FPV installation difficult in certain regions.

The higher energy yield provided by the cooling effect of FPV can only be achieved at high ambient temperatures which undermines the potential benefit of FPV installations in cold reg ions.

On the whole, development of FPV represents a significant advancement in RE technology and offers high energy output with minimal environmental impact. But, to fully realise this potential, FPV technology needs improvement.

Addressing challenges such as safety concerns, standardisation issues and policy considerations will be crucial to encourage widespread adoption. ESI

About the author

ESI Africa
Content Team
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