First demonstration prototype of floating photovoltaic system on slurry pond

Floating PV technology is already an alternative to the use of land or roofs for installing solar modules on water ponds. This type of installation has certain advantages, such as eliminating the need for land or roof space for the panels, or the extra cooling provided by the water surface. In a twist on these concepts, the research project “Alternatives in the use and control of slurry pond potential” has installed the first floating system to produce photovoltaic energy on the surface of a pig slurry pond.

Following on from previous posts in this news blog (“Intergia receives funding for collaboration in a technological innovation project for the energy use of slurry ponds” and “First test run of the project for the control and use of slurry ponds“), we now write about the latest developments.

The research project started in 2020 and consists of three key phases or tasks:

As part of the first phase, the possible technologies to be used were analysed (from the technical-economic point of view and the chemical resistance of the materials to the ammonia environment) and the components to form part of the pilot prototype were selected; the design of the prototype and the tests to be carried out were started and the measurements of ammonia emitted by the pond were begun.

Within the framework of the second phase, the design of the final prototype to be installed in the pond has been updated and completed. This includes engineering, list of materials, logistics and deciding how the assembly and maintenance will be carried out (health and safety aspects, etc.). In addition, measurements of the ammonia levels on the free surface of the basin have been continued and a first test of flotation and interaction between the floating cover elements that form part of the system has been carried out.

The final prototype is a 20.7 kWp PV system with 20 kW inverter power. It has 46 photovoltaic panels placed on support floats. The system will be capable of producing an annual PV generation of 34,378 kWh. According to calculations, this generation will cover approximately 38% of the farm’s electricity consumption. On the other hand, the proposed prototype, taking into account its combination with hexagonal plastic elements to cover free spaces between floats, manages to cover approximately 35% of the surface of the pond.

Therefore, the third phase is the last stage of the project: the assembly of the pilot prototype on the slurry pond at the selected farm and the evaluation of its performance under real operating conditions.

The assembly process has been similar to that of any other floating installation on a body of water: float units have been assembled with their corresponding panel; these units have been joined together to form rows of panels; and they have been dropped into the raft as these rows have been completed. As part of the research, different material components have been tested within the same prototype to assess their degradation in the adverse environment and to determine their suitability for this application.

The system has been set up with perimeter float walkways that can be walked over and an access platform. This facilitates access to the system, both for possible visits for information purposes and for maintenance and data collection.

Once the system is functionning, it will start operating to supply part of the farm’s electricity consumption (typically heating, lighting, automation, etc.). It is expected to be ready by the end of November. The last thing that remains to be done is to pour the hexagonal plastic elements that were already tested in the initial test in the water pool. These elements will be placed in the gaps between the floats, covering the free surfaces of the pool.

Measurements of ammonia levels will continue to be carried out periodically as before. The performance of the prototype in the pond will also be analysed, so that the following aspects will be evaluated:

• Existence of emission reductions due to the covered surface of the pond.
• Observable physical degradation of the materials of the floating PV system.
• Dirt and system cleaning and maintenance needs.
• Problems in the electrical operation of the system due to degradation by ammonia environment.

The results obtained from the project will be published and communicated at a dissemination event. It is intended, based on this project at regional level, to continue the line of the study by replicating the experiment on different farms, with a view to a possible commercialisation of the solution.

In addition, although the research project is scheduled to end in October 2023, the demonstration prototype will continue to be installed and operate in the pond, providing energy to the farm in the form of self-consumption with surpluses under compensation. Its correct performance will continue to be studied by the Intergia team, who will be responsible for timely preventive maintenance.