NREL Researchers Outline Roadmap to Advance Tandem Solar Cell Commercialization

Researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL) have laid out a comprehensive roadmap aimed at advancing the commercialization of tandem solar cells, particularly those integrating different photovoltaic (PV) technologies.

In a recently published article in the journal Joule, the researchers emphasized the imperative for the expansion of solar power globally, projecting a need for 75 TW of PV capacity by 2050 to meet the demands of a growing population and increased electrification across all energy sectors.

Unlike traditional single-junction solar modules, tandem solar cells, which incorporate two or more junctions, offer the potential for significantly higher efficiencies. By stacking multiple junctions, tandem cells can absorb a broader spectrum of sunlight, thus increasing efficiency while potentially reducing overall system costs.

Lead author Kirstin Alberi, director of the Materials Science Center at NREL, highlighted the historical use of high-efficiency III-V multijunction solar cells primarily in space applications. However, she noted that newer hybrid tandem modules, leveraging more scalable PV technologies, are now under development by both major manufacturers and startups, albeit not yet at a mass-production stage.

Alberi and her coauthors outlined key advancements necessary to propel tandem solar cell technology towards commercialization. These include achieving record efficiencies at the cell level, addressing reliability and durability concerns, and streamlining the design of hybrid tandem PV modules and systems for rapid deployment.

“Metal halide perovskites are viewed as an initial enabler of hybrid tandems from a cost and efficiency perspective. They provide high enough efficiencies as a top cell and are also cost-effective enough to incorporate that the tandem would have much higher efficiencies than the single-junction cells of either technology,” Alberi said.

The concept of hybrid tandems combines different PV technologies to maximize efficiency. Materials such as metal halide perovskites are identified as potential enablers due to their high efficiency and cost-effectiveness.

“Existing consortia have proven to be immensely helpful in the development and commercialization of single-junction PV technologies because they can help in information sharing, advocating for cross-cutting research that will help the field as a whole, and focusing larger sets of stakeholders to work together to solve problems that impact the entire field,” Alberi said.

The roadmap highlights the need for collaborative efforts akin to existing consortia in the PV industry. Such collaborations, the researchers argue, are crucial for information sharing, advocating for cross-cutting research, and addressing common challenges to accelerate the commercialization of tandem solar cell technology.