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Title: Simplified module assembly using back-contact crystalline-silicon solar cells

Abstract

The authors are developing new module concepts that encapsulate and electrically connect all the crystalline-silicon (c-Si) photovoltaic (PV) cells in a module in a single step. The new assembly process (1) uses back-contact c-Si cells, (2) uses a module backplane that has both the electrical circuit, encapsulant, and backsheet in a single piece, and (3) uses a single-step process for assembly of these components into a module. This new process reduces module assembly cost by using planar processes that are easy to automate, by reducing the number of steps, and by eliminating low-throughput (e.g., individual cell tabbing, cell stringing, etc.) steps. The authors refer to this process as monolithic module assembly since it translates many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Preliminary development of the new module assembly process, and some estimations of the cost potential of the new process, are presented.

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
OSTI Identifier:
548684
Report Number(s):
SAND-97-1228C; CONF-970953-
ON: DE98001179; BR: EB2202000; TRN: AHC29724%%85
DOE Contract Number:
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: 26. IEEE photovoltaic specialists conference, Anaheim, CA (United States), 29 Sep - 3 Oct 1997; Other Information: PBD: [1997]
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; SILICON SOLAR CELLS; BACK CONTACT SOLAR CELLS; FABRICATION; COST; PRODUCTION; AUGMENTATION

Citation Formats

Gee, J.M., Garrett, S.E., and Morgan, W.P. Simplified module assembly using back-contact crystalline-silicon solar cells. United States: N. p., 1997. Web.
Gee, J.M., Garrett, S.E., & Morgan, W.P. Simplified module assembly using back-contact crystalline-silicon solar cells. United States.
Gee, J.M., Garrett, S.E., and Morgan, W.P. Sat . "Simplified module assembly using back-contact crystalline-silicon solar cells". United States. doi:. https://www.osti.gov/servlets/purl/548684.
@article{osti_548684,
title = {Simplified module assembly using back-contact crystalline-silicon solar cells},
author = {Gee, J.M. and Garrett, S.E. and Morgan, W.P.},
abstractNote = {The authors are developing new module concepts that encapsulate and electrically connect all the crystalline-silicon (c-Si) photovoltaic (PV) cells in a module in a single step. The new assembly process (1) uses back-contact c-Si cells, (2) uses a module backplane that has both the electrical circuit, encapsulant, and backsheet in a single piece, and (3) uses a single-step process for assembly of these components into a module. This new process reduces module assembly cost by using planar processes that are easy to automate, by reducing the number of steps, and by eliminating low-throughput (e.g., individual cell tabbing, cell stringing, etc.) steps. The authors refer to this process as monolithic module assembly since it translates many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Preliminary development of the new module assembly process, and some estimations of the cost potential of the new process, are presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Nov 01 00:00:00 EST 1997},
month = {Sat Nov 01 00:00:00 EST 1997}
}

Conference:
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  • This paper summarizes recent progress in the development of back-contact crystalline-silicon (c-Si) solar cells and modules at Sandia National Laboratories. Back-contact cells have potentially improved efficiencies through the elimination of grid obscuration and allow for significant simplifications in the module assembly process. Optimization of the process sequence has improved the efficiency of our back-contact cell (emitter wrap through) from around 12% to near 17% in the past 12 months. In addition, recent theoretical work has elucidated the device physics of emitter wrap-through cells. Finally, improvements in the assembly processing back-contact cells are described.
  • We study an amorphous/crystalline silicon heterojunction (Si HJ) as a back contact in industrial standard p-type five-inch pseudo-square wafer to replace Al back surface field (BSF) contact. The best efficiency in this study is over 17% with open-circuit (Voc) of 0.623 V, which is very similar to the control cell with Al BSF. We found that Voc has not been improved with the heterojunction structure in the back. The typical minority carrier lifetime of these wafers is on the order of 10 us. We also found that the doping levels of p-layer affect the FF due to conductivity and bandmore » gap shifting, and an optimized layer is identified. We conclude that an amorphous/crystalline silicon heterojunction can be a very promising structure to replace Al BSF back contact.« less
  • This paper summarizes recent progress in the development of back-contact crystalline-silicon (c-Si) solar cells and modules at Sandia National Laboratories. Back-contact cells have potentially improved efficiencies through the elimination of grid obscuration and allow for significant simplifications in the module assembly process. Optimization of the process sequence has improved the efficiency of our back-contact cell ({open_quotes}emitter wrap through{close_quotes}) from around 12{percent} to near 17{percent} in the past 12 months. In addition, recent theoretical work has elucidated the device physics of emitter wrap-through cells. Finally, improvements in the assembly process using back-contact cells are described. {copyright} {ital 1999 American Institute ofmore » Physics.}« less
  • Thin hydrogenated amorphous silicon (a-Si:H) layers deposited by hot-wire chemical vapor deposition (HWCVD) are investigated as emitters and back-surface-field (BSF) contacts to make silicon heterojunction solar cells on p-type crystalline silicon wafers. A common requirement for excellent emitter and BSF quality is minimization of interface recombination. Best results require immediate a Si:H deposition and an abrupt and flat interface to the c-Si substrate. We obtain record 16.9% and 14.8% efficiencies on p-type planar float-zone (FZ) and Czochralski (CZ) silicon substrates, respectively, with HWCVD a-Si:H(n) emitters and Al-BSF contacts. Initial efforts with p-type HWCVD Si thin films as the BSF havemore » yielded 12.5% efficiency on p type CZ-Si.« less