Norway-based Ocean Sun was founded three years ago with the aim of disrupting the status quo in the solar industry. Its vision is to provide the technology that rapidly makes clean energy production the cheapest alternative to large populations around the world.
To achieve this, it has developed technology that will enable large-scale solar developments on coastal seawater, lakes, and reservoirs. The products are dubbed floaters, the flagship product has a diameter of 72m with an area of approximately 4000m2. They are based on utility type, dual-glass, crystalline silicon modules with a customized junction box, cables, and attachment features.
The modules can be rapidly and securely attached to the membrane enabling good thermal contact with the waterbody. The membrane itself is non-permeable and is a barrier against the waterbody, designed to withstand mechanical stress and sun exposure.
Some like it hot
Because of the horizontal orientation of the modules and the solar elevation angle, the product is best suited within 45 degrees latitude. It is no surprise that the target areas are some of the hottest regions on the planet such as Australia, the Sahara Desert, and the Middle East, that blanket some of the most populated areas on the globe. “That was the starting point for Ocean Sun to have this in the back of our heads,” Arnt Emil Ingulstad, co-founder and CSO of Ocean Sun says. “According to data from the World Bank, there contain nearly 400,000 square kilometers of man-made reservoirs alone.
“If you utilize one percent of that area or we can maybe go as much as five percent, still a tiny portion of these vast areas of water surfaces, it adds up to a two-terawatt business. Two terawatts are approximately a $2 trillion business, assuming approximately one dollar per watt installed. We will probably see the prices dropping in the future, but as of today, it’s approximately 1:1, $1 dollar per watt.”
Replacing ineffective platoons
The technology that is currently serving this market is markedly different from Ocean ‘Sun’s approach in that it uses platoon-based cones. “These platoons are polyethylene plastic and crystalline solar modules, regular modules that you put on the rooftops,” Ingulstad says. “They are mounted on top of these to utilize the water surface. It is not really a robust solution for motion, and it’s also tough to install.”
For its solution, Ocean Sun turned to biomimicry. This is the imitation of the models, systems, and elements of nature to solve complex human problems. “We started looking at different ideas such as giant lilies, the Victoria amazonica,” Ingulstad explains. “They sit there performing photosynthesis. What we have come up with is something that looks similar. But we are conducting photovoltaics, which is basically the same principle. We have a thin membrane coating, and we try to collect the energy of the sunlight, not for photosynthesis, but for electricity production.
“Our floater consists of a ring of a reinforced, one-millimeter thick membrane that is hydroelastic. On top of this membrane, we fix crystalline PV modules, solar modules but with some small modifications.”
Before the system could be released commercially, it had to undergo a rigorous regime of test and qualification. It has been on trial for two years at a basin test site at the University of Trondheim, NTNU, where they have been examining simulations of the forces and the movements of all the elements of the system.
“It is important for us the stress test the system,” Ingulstad adds. “We needed to qualify the performance to make it bankable. There’s a long way to go, but looking at the extremes is very important to us to establish confidence in what we’re doing. Measuring the forces that occur across the membrane and then, with the waves. Another issue is wind, and we are now building a demonstration plant in the Philippines. That is in the typhoon belt with winds up to 275 kilometers per hour.
“We have carried out some computational analysis, state of the art, looking at wind, heating our structure, the ring, and the rain. The good thing about the design we have is that we are virtually sitting on the surface, so there is not much room for the wind to get underneath the structure. We fit our modules onto a membrane that is in direct contact with the body of water.”
A recent success came in Albania when Statkraft ordered a floating solar plant with a maximum capacity of 2 MW for the Banja reservoir in Albania. The solar park will consist of four floating units of 0.5 MW each, with a total investment cost of €2.3 million.
The contract is the first major commercial contract for the system, and the project will demonstrate the viability of the technology. If the technology is proven successful, and the potential for cost-competitiveness can be achieved, a broader application of floating solar may take place in other Statkraft locations.