July 6, 2021
Glint spoke with Josefine Selj, a research scientist at the Institute for Energy Technology, Norway
It depends on the technology. Several recent results and publications indicate that the cooling effect on the typical pontoon-based floaters is modest. For FPV installed above the water surface without direct contact with the water, the operating temperature of the module will, as for land-based systems, predominantly be determined by the mounting structure (which greatly affects the U-value), wind and air temperature.
However, for FPV technologies which are in direct contact with water, or very close to direct contact with water, the water temperature will constitute the ambient medium on one side. As water absorbs heat more efficiently than air, the water temperature and water flow will greatly affect the PV module temperature of such systems. This can lead to a significant cooling effect. The cooling effect of FPV is therefore greatly dependent on the specific FPV technology.
For pontoon-based structures it is predominantly the mounting structure (which greatly affects the U-value), wind and air temperature. In addition, humidity may play a smaller role. For FPV technologies lying on or very close to the water surface, the water temperature and water flow is the most important parameters in addition to the details about the mounting structure itself.
The pontoon-based technologies do have several challenges, from logistics to wind/wave resilience. It is therefore natural to assume that it will be possible for some of the “new” FPV technologies to secure a significant share of the floating solar market. The most obvious first FPV markets for the technologies “lying” on the water surface are in windy places around the equator, but there is no obvious reason why they should not also be able to obtain large market shares globally.
IFE has been monitoring three different FPV systems over several years, with another two commercial systems and a couple of pilots coming online this year. The systems span a broad range of FPV technologies. One of the systems is a classical pontoon-based system from Ciel & Terre, while three of the systems are using the established and patented Ocean Sun technology. In addition, we will be analyzing data from three different new, Norwegian FPV technologies.
Generally, the performance ratio of the FPV systems we have analyzed is good. We have also established that the pontoon-based systems can be reasonably well modeled with existing modelling software such as PVsyst. To model the performance of the systems “sitting” on the water surface, water temperature and water flow must be included.
Although FPV has come a long way to establish itself as a new pillar of solar energy, there is still much work to be done. It will be important to collect and analyze more long-term data from various FPV technologies to assess degradation, reliability and life-time of the systems greatly. It will also be important to establish modelling tools and methods that are suited for all types of FPV systems. This is critical to accurately predict the yield of the system over the lifetime, and hence LCOE. There is also important work to be done regarding hybridization of FPV with hydro and to address O&M specifically for FPV. Just to mention a few…
The peculiarities of FPV power plant construction and operation are a remarkably good fit for a broader Norwegian industry, with its strong industrial experience and competence base in both PV, maritime technology and hydropower. Therefore, the competence of Norwegian companies and individuals provides us with a great possibility to contribute to an important development in this field. The FPV value chain also opens up for broader participation; Norwegian companies can contribute as developers and providers of components and structures, as service providers, developers and operators of FPV power plants world-wide.
Thank you for talking with us, Josefine!
Photo from Arnfinn Christensen, forskning.no