Floating Photovoltaics Opportunities and challenges

Floating PV systems (FPV) are slightly different than the conventional PV where FPV systems are mounted on a structure that floats on water surface, such as dams and ponds, and can be associated with existing grid connections for instance in the case of dam vicinity. The development of the floating PV on man-made waterbodies is a solution to land scarcity in high population density areas. There are different concepts in FPV for example, tracking, concentrated FPV, Membranes and mats type and finally Submerged FPV.

The FPV technology is still in the development stage. Since 2016, it started growing very fast reaching a 1.6 GW total installed capacity at the end of 2019, and a forecast of 4.8 GW by 2026. It can go beyond that if the technology development and the energy demand continued growing very fast. It is not only about seas and rivers, however, as for example, the USA have over 24 thousand of manmade water bodies that are applicable for FPV. Those are in different areas which can directly be connected to end-user to minimize the losses.

Studies showed that the evaporation savings from FPV is around 15,000 – 25,000 cubic meters of water for every MWp, which normally covers between 7-10 Hectares. However, this can easily vary depending on the weather conditions . Although the FPV utility-scale plants costs vary depending on multi factors such as water level variation, depth of waterbody and the project location, the LCOE of FPV is still 20% higher than the mounted-based plants, 35% of its total cost is for the floating platform.  Improvement in manufacturing process will boost the price down. Moreover, further development in the field will make the LCOE more competitive, this includes the improvement of the water effect on the structure that will affect the capital cost.  By installing PV on water reservoirs, it has been shown that PV limits evaporation and algae grow. Since wind speeds over open water tends to be higher than over land, thus facilitating module cooling, plants on water bodies are rarely shaded by nearby objects or buildings, water bodies tend to be less dusty than the arid desert locations. The PV operating temperature for FPV is 5-10 °C less than the conventional ones, which increases both the system efficiency and the performance ratio of the FPV by about 10%, 10%, respectively, compared to the onshore PVs. The latest mentioned fact is the only thing that will be needed to be considered during the FPV design stage compared to the onshore solar plants. A plus point in the offshore PVs is that in most cases there are no shading, which makes the production more optimum compared to the onshore PVs.

A main advantage for the FPV application is that since the land is scare in many countries, certainly close to consumption hubs, where it matters even more to install PV massively and largescale installation could play an important role, but the potential is limited. Moreover, easier installation and deployment simpler than for ground-mounted PV as no civil work is needed to prepare the site

A major challenge to the application of FPV is the capital expenses. As the capital costs of FPV are currently still slightly higher than or at best comparable to those of ground-mounted PV, owing chiefly to the expenses for the floats, mooring and anchoring, and more stringent requirements for electrical components. In addition, operation & maintenance activities are generally more difficult to perform on water than on land. Boats are usually required to access PV arrays, even for installations with maintenance pathways, and the anchoring must withstand wind load, waves, and potential currents, with the assurance of the electrical safety and long-term reliability of the system components.

In addition, most floats are bulky and have a very low weight-to volume ratio, making them difficult to ship. The cost of transporting them to remote locations may be prohibitively high. Moreover, the birds’ droppings are negatively affecting the system production. This shall be considered during the design stage and the operation and maintenance plan.