Singapore has positioned itself as knowledge hub for floating PV. The city-state’s Housing and Developing Board HDB), the leading agency spearheading solar initiatives and accelerating solar adoption in Singapore, is presently researching the sea as a potential space for floating photovoltaics.
Singapore has already launched the world’s largest floating PV testbed on Tengeh Reservoir in Tuas, with a total installed capacity of around 1 mwp. The testbed aims to study the technical, economic and environmental feasibility of deploying large-scale floating PV systems, usually mounted on a pontoon-based floating structure, on water bodies.
Now, the experts will look at how the HDB-designed floating modular system can hold solar panels in open-sea conditions. Dr Thomas Reindl, deputy chief executive of the Solar Energy Research Institute of Singapore (SERIS), says “off-shore,” in this context, refers to areas still within the territory of Singapore, which are not exposed to very rugged marine conditions. Nevertheless, challenges include corrosion from the salty sea water and other issues such as bird droppings. Another factor to consider is biofouling: Growth of barnacles and other marine lives on the floats has to be considered during design and operation, Reindl points out.
Advantages of floating PV include no or reduced land usage, which is attractive for regions where land is scarce or rather needed for agricultural use, but where sufficient water bodies are available.
Advantages of floating PV compared with land-based installations
The evaporative cooling effect from the water lowers the operating module temperatures, which could result in overall increases in the system’s annual energy yield of up to 25%, compared with land-based PV systems. Shading is virtually a non-issue on open water. What is more, floating PV offers itself to be combined with hydro-power stations, as electricity connections already exist and the reservoir could essentially be used as a “big battery.” A floating PV system can potentially reduce water evaporation losses from reservoirs for fresh water supply and irrigation, and algae growth could decrease because less sunlight reaches the water body. Lastly, aquaculture and fish farming could feasibly be integrated in floating PV installations.
Location: Balancing with competing maritime space uses
In Singapore, Reindl tells the media, the location for off-shore floating photovoltaics would need to compromise between the distance from the main island (to avoid too lengthy submarine cable connections) and uses competing for marine space, such as recreation, protected marine life areas, shipping routes and now a marine park.
In the testbed environment on Tengeh Reservoir, the performance ratio of the best floating PV systems (different types were deployed and measured) reached performance ratio (PR) values well above 80%, even in Singapore’s hot climate. The water-based systems were referenced against a rooftop reference system using the same modules.
Initial research results
SERIS reports the collected testbed data shows that the evaporative cooling effect depends on the type of floating structure and the way the PV panels are mounted. Higher values of the heat loss coefficient correspond to better cooling, and thus lower module temperatures, leading to a better electrical performance.
Written by Sandra Henderson, Research Editor, Solar Novus Today