Popular NREL cell efficiency chart now better presents tandem solar photovoltaics

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NREL Photovoltaics researchers create new version of iconic graph that tracks world record PV cells across many technologies and time

The Best Research Cell Efficiency Chart is one of the most visited pages on the National Renewable Energy Laboratory (NREL) website. It regularly appears in presentations at photovoltaic (PV) research conferences, tracking the emergence and maturation of new PV technologies.

Like the technologies it tracks, the graph continues to evolve. Recently, NREL has developed an interactive version of the chart and started publishing the underlying data table, allowing users to dive deeper.

Now, the NREL team responsible for maintaining the map is implementing an update to the map's technology categories.

Add a hybrid tandem category

Due to growing interest in tandem PV (cells composed of two separate absorbing layers to capture a larger portion of the solar spectrum), the NREL team has added a new category of 'Hybrid Tandems' to the chart . This category collects record tandem cells with layers composed of two different PV materials. Some subcategories of hybrid tandems (Perovskite/Si and Perovskite/CIGS) were already present in the previous format under “Emerging PV”, while others (III-V/Si and Perovskite/Organic) are new.

All of these subcategories have been moved to the new Hybrid Tandems category, with the exception of perovskite/perovskite tandems, which are listed under Emerging PV.

View the updated version below or as PDF. The new changes can also be seen in the interactive version of the Best Research-Cell Efficiency Chart.

A condensation of the III-V Multijunction category

This updated version also makes changes to the “III-V Multijunction Cells” category, which has long contained the highest efficiency cells on the board. To simplify the very busy map, all III-V concentrator cells are now combined into one subcategory, with the number of nodes listed on each point's label. Three and four junction non-concentrator cells are also combined in a subcategory “Three junctions or more”.

A new subcategory under emerging PV

With growing interest in and examples of independently verified efficiencies for all-perovskite two-terminal tandem cells, the NREL team has also added a new subcategory under the Emerging PV category on the map. The new subcategory “Perovskite tandem cells” will list the absolute record efficiency for all-perovskite tandems with two connections, regardless of the number of intersections.

Overall, these changes reflect recent developments in new cell types and make the chart a more complete reference for record cell efficiencies.

Call for community feedback

NREL is seeking input from the community of PV researchers and manufacturers on these changes to the Best Research-Cell Efficiency Chart. As a fixture in the PV community, NREL wants to ensure these changes are beneficial.

Send comments and feedback to [email protected].

Learn more about NREL's research on PV device performance.

Check out the related ones Efficiency chart for Champion photovoltaic modules.

For general questions about NREL's record efficiency charts and PV device performance research, Contact Nikos Kopidakis.

Thanks to NREL. By Harrison Dreves