PERC and beyond – next generation modules, what can we expect?
Webinar: 09.05.2019
Cells and modules with
passivating contacts -
POLO technology
F. Haase, R. Peibst
Institute for Solar Energy Research Hamelin (ISFH)
Am Ohrberg 1, 31860 Emmerthal, Germany
www.isfh.de
ISFH
• Founded in 1987
• 10.2 Mio € turn over (2017)
• 145 employees
• R&D in photovoltaics and solar systems
• R&D in cooperation with industrial
partners
• Focus on applied research in c-Si PV
09.05.2019Webinar: PERC and beyond
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PERC+ solar cell
• PERC cell with local contacts at
the rear but full area aluminum
• PERC+ cell with Al fingers for
bifaciality and less aluminum
consumption and bow [1]
[1] T. Dullweber et al., Proc. of the 31st EUPVSEC, p.341 (2015).
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PERC+ solar cell - limitations
• Current industrial PERC+ cells are
limited by emitter and contact
recombination[1]
• Are there less limiting contacts?
[1] C. Kruse et al., IEEE Journal of Photovoltaics 8 (3), 683-688, (2018).
e-selective contact
h-selective contact (Al-BSF)
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Poly-Si on oxide (POLO) is a nano-PERC
• Efficiency limitation by contacts:
25 %[1,2]
PERC POLO
P-doping 1020 cm-3
1 µm
5 nm2 nm
Al-doping 5x1018 cm-3
1 mm
100 nm
50 µm
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• Efficiency limitation by contacts:
29 %[1]
• Less contact fraction but still less
contact resistance
[1] R. Brendel et al., Proc. of the 35th EUPVSEC, p. 39 (2018)
[2] J. Zhao et al., Appl. Phys. Lett. 73 (14), p. 1991-1993 (1998)
POLO – double side contacted industrial
solar cell concepts
• Various cell concepts / process sequences / poly-Si depositions under
investigation[1]
• Benefit of POLO: high-temperature stable, compatible with high-T. screen-print
→ Possible “add-on” for PERC mainstream
• Using mostly same process equipment could be interesting for upgrading
existing PERC lines
• Metal layout same as for PERC → Module integration similar as for PERC
609.05.2019Webinar: PERC and beyond
F. Haase
[1] R. Peibst et al., accepted as presentation at 36th EUPVSEC (2019)
POLO – double side contacted industrial
solar cells
• Efficiency gain over PERC (simulated with measured input parameter):
+0.2-0.4 % +0.2-0.4 % +0.8-1.2 % +1.4-1.8 % +0.6-0.9 %
• Costs depend on number of process steps (can be more or less than PERC)
709.05.2019Webinar: PERC and beyond
F. Haase
PERC+ POLO-RS PERC+POLO POLO2-FJ POLO2-BJ TOPCon
p+ and n+ POLO junctions: POLO-IBC cell
• POLO-IBC solar cell
• P-type Si world record
• h = 26.1 %[1] independently confirmed
at ISO17025-accredited Calibration
and Test Center, ISFH-CalTeC
[1] F. Haase et al., Solar Energy Materials and Solar Cells 186,184 (2018)
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Industrial POLO-IBC cell[1]
• Same process equipment as PERC+
except poly-Si deposition tool
• 25 % efficiency potential simulated
[1] F. Haase et al., accepted as presentation at 46th IEEE PVSC 2019
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POLO-IBC module
• Ribbon or Multiwire cell
interconnection possible
• Same process equipment for
module manufacturing as PERC+
Multiwire
• High robustness against efficiency
losses by cell cracks
• High efficiency modules for vehicle
integrated PV
[1] M. Hendrichs et al., Proc. of the 42nd IEEE PVSC (2015), DOI: 10.1109/PVSC.2015.7355645
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Wire cell interconnection without busbars[1]
POLO cells – degradation mechanisms
Known from PERC and also relevant for
POLO
• Light Induced Degradation (LID)
• Light and elevated Temperature
Induced Degradation (LeTID)
• Potential Induced Degradation (PID)
of bifacial cells
Degradation of POLO contacts
under investigation
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LeTID on multicrystalline PERC cells [1]
[1] K. Ramspeck et al., Proc. of the 27th EUPVSC, 861 (2012)
Conclusion and Outlook
• PERC will stay mainstream and keep on improving
• Pioneer work of ISFH to working principle and potential of POLO contacts
• POLO contacts do not limit the cell anymore
• 26.1 % record efficiency with POLO-IBC
• Various cell concepts / process sequences / poly-Si depositions under
investigation
• First production lines built for passivating contacts
Webinar: PERC and beyond
F. Haase09.05.2019 12
Acknowledgments
13
Many thanks to
• … director Prof. R. Brendel and the whole team @ ISFH and MBE
• … industrial partners
• … the federal state of Lower Saxony, the German Ministry for Economic Affairs and Energy,
and the European Commission for funding
• … you for your kind attention!
For further questions please contact:
Dr. Felix Haase
www.isfh.de
09.05.2019Webinar: PERC and beyond
F. Haase
