Homogenous Voltage-Matched Strings Using Three-Terminal Tandem Solar Cells: Fundamentals and End Losses

Journal Article · Wed May 12 04:00:00 EDT 2021 · IEEE Journal of Photovoltaics

DOI:https://doi.org/10.1109/jphotov.2021.3068325· OSTI ID:1785087

McMahon, William E. ^[1]; Schulte-Huxel, Henning ^[1]; Buencuerpo, Jeronimo ^[1]; Geisz, John F. ^[1]; Young, Michelle S. ^[1]; Klein, Talysa R. ^[1]; Tamboli, Adele C. ^[1]; Warren, Emily L. ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Strings constructed from three-terminal tandem (3TT) solar cells offer the performance benefits of voltage-matching (which reduces sensitivity to spectral variation), but without the subcell voltage isolation required by four-terminal cells. However, the circuitry for a 3TT string can become complex, making circuit analysis more challenging. Here, we illustrate the essential features of “homogenous” voltage-matched (VM) 3TT strings, for which all 3TT cells in the string are nominally identical (with the same design/doping sequence, such that they can be fabricated on the same manufacturing line). Several representative VM string configurations are explicitly considered, and used to describe the general construction of string I(V) curves. End losses intrinsic to these strings are discussed in detail, along with mitigation strategies to minimize their impact. Our analysis agrees with experimental results for eight-cell strings constructed from GaInP/GaAs 3TT devices.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1785087
• Report Number(s): NREL/JA-5900-78778; MainId:32695; UUID:e23a57d4-05ed-4616-ae40-c79e75ba1920; MainAdminID:21142
• Journal Information: IEEE Journal of Photovoltaics, Journal Name: IEEE Journal of Photovoltaics Journal Issue: 4 Vol. 11; ISSN 2156-3381
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
PV cells
photovoltaic
solar cells
solar stringing
tandem cells
three terminal
voltage matched