Floating Solar Panels at High Altitudes Offer Quick Energy Payback of 2.8 Years

New research from Switzerland has demonstrated that alpine floating photovoltaic (PV) systems can surpass lowland or ground-mounted counterparts in energy yield and sustainability. Scientists identified that the primary potential for material reduction in these floating PV installations lies in the resource-intensive mounting system.

Researchers at the Zurich University of Applied Sciences analyzed the life cycle environmental impact of the world's first high-altitude floating PV system, discovering an energy payback time of just 2.8 years.

This 448 kW system, constructed in 2019 by Swiss energy provider Romande Energie, is located on the surface of Lac des Toules, a reservoir situated at an altitude of 1,810 meters in the Swiss Alps.

"The installation consists of 35 platforms equipped with bifacial PV panels, covering a total area of 2,240 square meters, which accounts for 2% of the lake's surface," the scientists noted. "The structure is anchored at the bottom of the reservoir. It floats between mid-June and mid-December and rests on a platform on the reservoir's ground for the remainder of the year."

Their life cycle assessment (LCA) encompassed all processes, from the extraction of raw materials for the system's construction to its end of life. They compared the environmental performance of the installation with lowland and conventional systems across four scenarios.

"Primary data was provided by the energy company involved and covers all life cycle stages of the high-altitude floating PV installation," they explained. "Secondary data was sourced from literature, focusing on methodology guidelines by the International Energy Agency (IEA) and Product Environmental Footprint Category Rules (PEFCR)."

The analysis revealed that the high-altitude floating array emits approximately 94 grams of CO2-equivalent per kWh of electricity produced throughout its life cycle. Additionally, the system exhibited lower environmental impacts compared to other system types, due to its higher energy yield and reduced land use.

However, the "environmentally intensive" mounting systems were identified as a significant factor increasing the installation's environmental impact. These systems require more complex foundations and are preferably dual-piled, resulting in a higher usage of aluminum—up to eight times more than ground-mounted PV facilities.

The researchers emphasized that reducing aluminum in the mounting system would not only yield environmental benefits but also reduce the costs of the floating PV installation. "This can be achieved by minimizing the overall use of aluminum, using recycled aluminum, or replacing aluminum with alternative materials," they suggested.

The analysis also showed that the alpine installation had lower impacts in six out of twelve analyzed categories and higher impacts in the remaining six. "The non-renewable primary energy demand is 10,810 kWh oil-equivalent per kWp, equating to an energy payback time of 2.8 years," the researchers stated.

Their findings are detailed in the paper "Are alpine floatovoltaics the way forward? Life-cycle environmental impacts and energy payback time of the world's first high-altitude floating solar power plant," published in Sustainable Energy Technologies and Assessments.

"The present study contributes to the limited knowledge regarding the environmental performance of floating PV systems and provides insight into the environmental impacts of such installations at high altitudes," the scientists concluded. "The study highlights key areas for improving environmental performance while emphasizing the potential of this technology.