Sun-tracking Photovoltaics: A Revolutionary Solution for Stadiums

In a significant stride towards sustainable energy solutions for sports facilities, researchers from the University of Salerno and the University of Naples Federico II in Italy have engineered an innovative photovoltaic (PV) system tailored specifically for small-to-medium-sized sports stadiums. This groundbreaking design presents a novel approach to harnessing solar energy within the context of stadium architecture.

The newly developed PV system is a harmonious blend of metal roofing modules and lightweight, flexible PV panels. One of its most notable features is its lightweight construction, coupled with “exceptional” stiffness properties. According to Fernando Fraternali, the corresponding author of the research, the deployable structure designed to activate the sun-tracking mechanism has been meticulously crafted. “The sun-tracking mechanism's deployable structure has been designed in a manner that allows for effortless application to existing stadiums,” he informed pv magazine. “It can be seamlessly integrated into any stadium roof by appropriately connecting the bus cable to a supporting structure that is placed on top of the existing roof.”

In their paper titled “A tensegrity structure for a solar stadium roof with sun-tracking capability,” published in the esteemed journal Thin-Walled Structures, the research team delved into the details of their proposed design. They categorized it as a class-4 tensegrity system, where the structural integrity hinges on the equilibrium of the tension members.

The researchers further elaborated on the roof structure, which is identified as the V-expander. This term refers to the incorporation of a v-shaped rigid strut within the tensegrity structure. “The original V-Expander, as introduced by René Motro in his renowned textbook, is a V-shaped system comprising eight bars arranged in two distinct groups of four bars each, all of equal length,” they explained. “Our variation is a class-4 tensegrity structure that consists of eight bars and seven cables.”

The proposed PV roof cover is founded on triangular metal roofing modules, each equipped with sun-tracking PV panels. The motion that drives the tilting mechanism is initiated by a winch strategically positioned at an appropriate location. By adjusting the rest length of the bus cable, the system can achieve movement with an impressively low energy consumption rate.

“The sun-tracking strategy employs a tensegrity actuation technique, which is regulated by adjusting the rest length of a bus cable linked to the struts,” the researchers noted. “This mechanism enables the lightweight roof plates, which are covered with PV strips, to tilt in an optimal manner for maximum solar energy absorption. The PV strips can be fabricated from amorphous thin-film cells, organic PV cells, or flexible PV panels. Additionally, more conventional PV panels can be utilized, as long as their weight is carefully considered during the structural analysis.”

The proposed approach is said to offer a substantial boost to the annual electrical energy production capacity of the solar roof. Compared to a fixed-slope solar roof, it can increase the energy production by up to 54%. “The locally variable sun-tracking strategy proves to be particularly advantageous during the winter months, resulting in power production increases of up to 80%,” the academics highlighted. “When at rest, the lifting structure functions as a lightweight tensegrity system.”

The research group believes that the system holds significant potential for further optimization. They suggest that deploying its sub-units with varying tilting angles or utilizing two-axis solar trackers could enhance its performance. “Additional enhancements to the solar stadium design strategy might involve the adoption of high-efficiency silicon solar cells, which can achieve efficiencies of up to 27% – 28%, as well as the integration of bifacial cells,” they concluded. “Moreover, the concept of the tensegrity-stadium can be scaled up to accommodate large-scale stadiums, opening up new possibilities for sustainable energy solutions in the sports industry.”