FPV requires a special arrangement to keep it floating on water. A typical FPV system consists of a floating bed that houses the components of the PV system. In order to keep the platform intact with restricted movement, it is anchored and moored. The floating platform is an assembly of floaters mounted with modules, and other electrical components of the PV systems such as combiner boxes, inverters, transformers and walkways for maintenance. There are also special floats for the cables that connect to nearest loads.
As the platform is subjected to movements within a predefined range, the cables require special care regarding stability and safety. While the solar modules are always mounted on floats, combiner boxes, inverters and transformers might be placed on land, in case of small FPV systems close to shore. Naturally, floaters are the key component of an FPV system. The floating material must be lightweight so that it can stay afloat. It must also be resistant to corrosion from water and other chemicals, as well as environmental stress cracking from wind, waves, and frost. Finally, the material must be resistant to ultraviolet radiation and must not pollute the water environment. High-density polyethylene (HDPE) is a commonly used material for floating PV systems because it meets all the above required characteristics (see Power On Water) .
While there are several floater technologies available, they can be broadly categorized into 3 types:
Next to the floaters, anchoring and mooring systems are the key ingredients of the FPV system. They keep the floating PV array in place and prevent it from drifting away. They also help the system to be intact with changing water levels and highspeed winds. The anchoring and mooring system is typically composed of anchors, mooring lines, and buoys. The anchors are typically secured to the waterbed, and the mooring lines, typically nylon polyester ropes, connect the anchors to the floating PV array. The buoys help keep the mooring lines afloat and prevent them from dragging at the bottom.
Anchoring can be done in many ways. Bank anchoring is the simplest and economical, as the FPV system is anchored to the bank of the water body using cables and chains. However, itis typically used for smaller FPV systems in areas with calm waters. Bottom anchoring, being robust and flexible, is the most popular; however, it also has several variations. Gravity anchoring is a common one and is also relatively simple. It uses heavy weights, such as concrete blocks, to anchor the floating PV system to the bottom of the waterbody. Pile anchoring is more secure than gravity anchoring, but it is also more expensive given the cost of long metal tubes that are driven into the waterbed. This approach has high tolerances for water level variations and is typically used for larger FPV systems or in areas with strong currents or waves.
Suction anchoring is a relatively new technology, used in other marine applications with a potential application in FPV. It uses anchors that stick to the bottom of the water body through suction but requires suitable soil conditions. Drag anchoring is yet another variant, in which the anchors are dragged along the waterbed and are typically used in temporary setups. The type of mooring system mainly varies depending on the number of mooring lines and respective anchors, which could be single-point, 4or multi, and are prefixed respectively. The mooring system that is best for a particular FPV array will depend on a number of factors, including the size of the array, the environmental conditions such as windspeed, waves, currents and tides, and also the budget.
Survey participants
Like other applications of PV, FPV also requires several specific components. However, when breaking it down to products, floaters are what really differentiate this PV application from others. On top, the suppliers of these floaters, at least the leading ones, are also offering complete FPV solutions including design, planning, engineering, installations, commissioning, operation and maintenance, either on their own or through certified partners. This is also the rationale behind considering floaters only as a product-level subject in this first TaiyangNews Market Survey on FPV, which lists 13 products from9 suppliers including market leader.
Leaders are in: A total of 9 companies, including the market leaders of the segment, have provided input for TaiyangNews' 1st FPV market survey. (Source: TaiyangNews)
As mentioned above, these floaters can be divided into 3 categories. The most popular are the pontoon type, which are offered by the top 2 players –Sungrow and Ciel & Terre – as well as Fost and Isigenere. Metal-based mounting structures supported by floating bodies are offered by 4companies – Zimmermann, SolarisFloat, Swimsol and SolarDuck. The membrane-based solution has only one representation in the survey from OceanSun. The majority of the survey participants are focusing on inland waters and are often ready to install "near shore." In this context, SolarDuck earns a special mention, as the company exclusively focuses on offshore installations. SolarisFloat is also unique in that it offers a floating solution with sun tracking ability.
The text is an excerpt from the TaiyangNews Floating PV 2024 Report, which can be downloaded for free here.