Top image: Drone photo of the facility in Adventdalen. The season’s electricity production has just begun, but the snow drifts have grown large enough to partially bury a row of the plant. Photo: Iver Frimannslund/UNIS.
Field trials in Adventdalen outside Longyearbyen are investigating the potential and challenges of polar solar power plants.
21 April 2021
Text: Iver Frimannslund (NMBU/UNIS), Thomas Thiis (NMBU), Arne Aalberg (UNIS), Bjørn Thorud (Multiconsult).
Solar cell technology has in recent years undergone an incredible technological development and cost reduction and is already now the cheapest technology for power production many places in the world. But how does the technology work in polar regions? This is the subject of the doctoral work of Iver Frimannslund and supervisors at NMBU, UNIS and Multiconsult.
In polar regions, solar panels have long been used for power for off-grid technical installations such as weather stations, lighthouses, and telecommunication towers, and over time have proven to be a reliable solution. In addition, the dispersion of the technology has extended to building-mounted solar systems which cover both roofs and facades with solar panels. This use of solar power has required little adaptation from lower latitudes to polar climates and is a potential contributor to an increased share of renewable energy supply in Longyearbyen.
But building-mounted solar power plants have their limitations. The orientation and the tilt of the panels are dictated by the building’s orientation and architecture and not all places on a building have good irradiance conditions. There is also a natural size limitation for building-mounted solar power plants and the installation of such systems requires a degree of customization to the building’s surfaces. Avinor’s solar power plant at Svalbard Airport is an example of a solar power plant that is shaped by the building body where the size of the plant is limited by the available surfaces.
Therefore, it is desirable to explore the possibilities for larger ground-mounted solar power plants in Polar regions. Here, the orientation and tilt can be optimized for energy production, the size of the plant will not be limited by the available building surfaces, and the plant can be expanded over time. Large-scale ground-mounted solar power plants are increasingly common at lower latitudes, but what happens if you use the same design for solar power plants in Polar climates? What principles for the design of solar power plants can be transferred from solar power plant design theory and which new environmental stresses must be considered?
The field setup in Adventdalen
This was the research focus when NMBU (Norwegian University of Life Sciences) and UNIS joined forces to install a small ground-mounted solar power plant in Adventdalen by the old northern lights station. At the start of the project, it was clear that the climatic stresses would be different so that new knowledge must be developed for the correct design of such installations. One of the biggest questions was related to the establishment of snowdrifts in the plant and became a natural focus area for the study. Do we have to change the principles for the design of solar cell panel systems in Arctic regions, compared to the design principles we already know? How snowdrifts are formed depends mainly on the shape of the solar power plant rather than the material, and therefore it was decided to build a “mock-up” solar power plant from wood in Adventdalen. Simply explained, the plant consists of four rows of exposed surfaces facing the sun at a given angle.
In addition to researching the climate impact on solar power plants, the production potential was also of interest. There are no ground-mounted facilities at similar latitudes and a study of the system performance is new to the research field.
Of particular interest is the potential for the use of bifacial solar panels that produce electricity from both sides of the panel. Such panels can utilize the reflected radiation from the ground and are particularly beneficial for locations with a long-lasting snow cover. For this reason, solar panels were installed facing both the sky and the ground at the plant.
The plant was designed in line with traditional principles for the design of solar power plants and has an angle of 30 degrees and the panel surface is raised 1 meter above the ground.
Challenges and the potential of the polar climate
Shortly after the plant was installed in Adventdalen, it could be seen that snowdrifts began to form on the leeward side of the solar power plant. The snowdrifts gradually increased in size and became 1.8 m high and more than 50 m long at their largest. The snowdrifts grew not only away from, but also towards the facility where a row was finally partially buried. The results from the field measurements show that in order for ground-mounted solar power plants to be sustainable in areas with a lot of drifting snow, adaptations of the design are required.
The power production from the solar panels gave more uplifting results. The panel facing the sky produced 5% more than theoretical production calculations after normalizing to differences in irradiance. This may mean that the established calculation tools for solar power are not as accurate in Arctic regions as in southern regions. This may be due to errors in radiation measurements, radiation spectrum, temperature, or something else. Solar cells get hot when they produce electricity, which contributes to lower voltage and thus lower efficiency for the solar cells. In the experiment, we logged the temperature on the solar panel which turned out to stay very low throughout the experiment. This is of course a known phenomenon, but the experiment suggests that the cooling of the solar panel in the wind-exposed climate increase the performance and may be underestimated in the simulations.
The panel facing the ground produced as much as 37% of the panel facing the sky before the snow cover melted. After the snow cover melted, production dropped to 16% of the sky-facing panel, making clear the positive contribution snow cover has on the production for bifacial panels. In places where the snow cover lasts longer than it does in Adventdalen, the use of bifacial panels can be even more favourable. Another interesting phenomenon was that the solar cells facing the ground had a small production top due to the midnight sun in the summer. The polar summer can thus provide solar power around the clock.
The Polar climate has several advantageous characteristics for solar power production but presupposes that we can solve the new challenges that climate brings. To avoid snowdrifts, snow fences to deposit the snow before it enters the facility is a widely used solution. Another approach is to adapt the design of the plant itself so that either no snow accumulates, or that you use the design of the plant to deposit snow in designated areas. Solar power plants are flexible in design and there are many different ways to adapt the design where you reduce the risk of snow accumulation in unwanted places.
Exciting future for polar solar power plants
The possibilities for adapting ground-mounted solar power plants to the polar climate are many and that the snow drift challenge can be solved. From what we now know, polar solar power plants entail an extra risk associated with climate stress, but the results of solar power performance incentivise use of the technology.
The further work now lies in exploring what effect the design of solar power plants has on snow formation and what strategy is most appropriate to use to realize economically and environmentally sustainable solar power plants in Polar climates. The knowledge developed through the research project will hopefully contribute to the establishment of Polar, ground-mounted solar power plants with high performance, low costs, and with a low risk that the climate will reduce the plant’s operational lifetime. Polar solar power plants can be a relevant solution for Longyearbyen, and also for many other settlements in the Arctic and Antarctic.
The authors want to thank the Svalbard Environmental Protection Fund for support, goodwill from the Longyearbyen Local Community Council, help from Avinor and Power Controls AS.