Researchers Uncover Major Water Savings Potential In Solar Cell Manufacturing

Researchers from the Technical University of Berlin, Rena Technologies GmbH, and the Fraunhofer Institutes for Building Physics IBP and Solar Energy Systems ISE have developed a comprehensive model of water flows in a solar cell factory with a production capacity of 5 gigawatts (5 GWp) per year. This groundbreaking study, published in the latest issue of Solar Energy, explores the potential of circular water use strategies in solar cell manufacturing to significantly reduce water consumption and wastewater production.

Using their detailed model as a foundation, the researchers tested two distinct strategies for reusing water within the production process. The findings revealed that it is technically feasible to achieve up to a 79 percent reduction in water consumption and up to an 84 percent reduction in wastewater with current production technologies. These savings are substantial, suggesting that new solar cell factories could be built in regions with limited water resources without compromising efficiency or sustainability.

The study focused on analyzing the water consumption, wastewater, and material flows in a PERC (Passivated Emitter Rear Cell) solar cell production factory with an annual output of 5GWp. The insights gained from this analysis are also applicable to factories producing heterojunction or TOPCon (Tunnel Oxide Passivated Contact) solar cells, as these cell types have similar wastewater profiles.

Peter Brailovsky, a researcher at Fraunhofer ISE and one of the study’s main authors, explained that the team investigated various methods for conserving and recycling water in the production process. They identified two primary approaches: the reuse of low-contaminated wastewater (LCR) and the “Minimal Liquid Discharge” (MLD) approach, which involves recycling certain residual materials for use in other applications. For instance, etching solutions left over from solar cell production can be repurposed in cement production, reducing waste and conserving resources.

The results of the MLD scenario were particularly impressive, demonstrating that savings of up to 80 percent in both freshwater demand and wastewater production could be achieved in the modeled solar cell factory. The LCR approach also showed significant potential, with savings of up to 40 percent. Importantly, implementing these water-saving measures would not add to production costs; in fact, they would slightly reduce overall costs. Additionally, adopting a circular water strategy minimizes the risk of factory shutdowns due to water shortages, which can be costly during extreme weather events like heat waves.

Solar cells are inherently sustainable products, especially when integrated into photovoltaic modules. The energy required to produce them is quickly offset, typically within 1.3 years for photovoltaic systems in Central Europe. However, as Dr. Jochen Rentsch, head of Technology Transfer in the Division of Photovoltaics at Fraunhofer ISE, emphasized, the industry should not become complacent. Like all sectors of manufacturing, photovoltaics must strive to be part of a circular economy, continuously seeking ways to reduce environmental impact and resource consumption.

In conclusion, the study underscores the significant potential for water savings in solar cell manufacturing through the adoption of circular water strategies. These methods not only enhance sustainability but also offer economic benefits and reduce the vulnerability of production facilities to water shortages. As the solar industry continues to grow, integrating these innovative approaches will be crucial for ensuring that the production of solar cells remains environmentally responsible and economically viable.