NREL Advancing Tandem Solar Technology

Increasing module efficiency and expanding manufacturing capacity are key factors in reducing the costs of metal halide perovskite/silicon tandem solar modules, according to researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). These cost levers can have similar impacts depending on a manufacturer’s ability to scale production and enhance module performance.In a journal article coauthored by Michael Woodhouse and Emily Warren, the authors highlighted that module efficiency is a critical yet dynamic factor in predicting the cost of tandem modules. This is because numerous other variables will continue to evolve to achieve the efficiency and durability required for commercially viable photovoltaic modules. To remain price-competitive with other solar technologies, tandem modules must reach an efficiency of at least 25%.

The next steps toward commercializing perovskite/silicon tandem modules include improving the technology’s reliability in real-world conditions and scaling up high-efficiency devices to full module sizes without compromising performance.

Most photovoltaic (PV) modules produced today rely on single-junction silicon solar cells. However, by combining silicon with metal halide perovskites (MHPs) in a tandem configuration, manufacturers can develop solar modules capable of converting more sunlight into electricity than silicon alone. While this tandem technology shows promise, it remains in the early stages of development, with various integration approaches and significant uncertainties surrounding cost and performance.“One of the questions that this paper answers is, what is the value of that efficiency,” said Jacob Cordell, lead author of the paper, “Technoeconomic analysis of perovskite/silicon tandem solar modules. One key takeaway is that a 2.5% absolute efficiency gain in a module provides the same reduction in cost per nameplate capacity as doubling the size of your factory.”

To address these challenges, NREL researchers created a manufacturing cost model that integrates laboratory processes with existing equipment and supply chains to analyze different large-scale manufacturing approaches. Their study evaluated various methods for constructing tandem modules and examined the cost sensitivities related to materials, production equipment, factory location, and other factors. The analysis revealed that factory throughput and module efficiency are the most critical drivers of manufacturing costs.