Content uploaded by Stefan Wendlandt
Author content
All content in this area was uploaded by Stefan Wendlandt on Jul 15, 2021
Content may be subject to copyright.
Solyco Technology GmbH
IEEE PVSC 2021 June 20 – 25, 2021
TECC-Wire for the Interconnection of
Temperature-Sensitive Solar Cells
1Y. Zemen, 1L. Podlowski, 2S. Wendlandt and 2,3J. Stegmann
1Solyco Technology GmbH, Baseler Str. 60, Berlin, Germany
2Photovoltaik-Institut Berlin AG, Wrangelstr. 100, Berlin, Germany
2,3Beuth University of Applied Sciences Berlin, Luxemburger Str. 10, 13353 Berlin, Germany
Content
•Introduction
•of the Team
•Techniques for the interconnection of temperature-sensitive solar cells
•TECC-Wire Technology
•Status of R&D and test results
•Outlook
•Summary
IEEE PVSC 2021 June 20 – 25, 2021
•1996 – 1999 PV module manufacturing startup “SolarWerk GmbH”
•1999 – 2014 Part of SOLON´s technology division (for PV module
manufacturing and PV products R&D)
•2007 – 2011 Strategic partner of a manufacturer of flexible CIGS solar cells
and modules
•2015 – 2016 Part of First Solar´s „Tetrasun“ department (developed
the first commercial n-TOPCon cell and module)
•since 2017 Technology consulting firm and PV products R&D
Strategic partner of PI-Berlin for module QA projects
Introduction of the Team
IEEE PVSC 2021 June 20 – 25, 2021
Silicon heterojunction (SHJ) solar cells
•Low-temperature multi-wire soldering based on 9-12 wires which are
coated with a low-temp. alloy ( Risen)
•“SmartWire” by Meyer Burger – a low-temperature In- or Bi-based
soldering with 13 – 22 wires (REC; MB; HEVEL)
•Conductive adhesive paste-based interconnection (Enel; HEVEL)
•Conductive tape-based interconnection (Panasonic)
Techniques for the interconnection of temperature-sensitive
solar cells
IEEE PVSC 2021 June 20 – 25, 2021
Silver. Indium. Bismuth: Three key metals of concern for the PV industry
•Silver and indium are critical to Terawatt production level and need to be replaced
This is consensus
•New in focus is bismuth used as a low-temperature solder alloy more in SHJ
•It is important to assess the sustainability aspect of using bismuth before
scaling the Terawatt production level [1]
•The use of bismuth as a lead substitute in solder alloy as part of the
restriction of hazardous substances (RoHS) is generally not recommended [2]
Rare elements consumption in the PV industry
IEEE PVSC 2021 June 20 – 25, 2021
[1] M. Kim et al. “Towards Sustainable Silicon PV Manufacturing at the Terawatt Level”, UNSW, Sydney. 2052 Australia, 11th International
Conference on Silicon Photovoltaics – SiliconPV 2021, Hamelin. Germany
[2] European Copper Institute, “Recommendation on the non-use of bismuth for lead substitution”, September 2007,
https://copperalliance.eu/resources/recommendation-non-use-
TECC = Thermoplastically and Electrically Conductive Coating
- Very similar to multi-wire approach
- Wires are coated with an electrically conductive
thermoplastic (instead of a solder alloy)
TECC-Wire Technology
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D and test results
STC power and EL imaging analysis of TECC-Wire compared to other
means of electrical connection
•Busbar-less SHJ solar cells
Reliability testing
•Temperature cycling test (TC600)
•Damp heat test (DH500)
Industrial manufacturing with automated stringing machine
IEEE PVSC 2021 June 20 – 25, 2021
TECC-Wire Technology
IEEE PVSC 2021 June 20 – 25, 2021
•The wire has a core of Cu with a typical
thickness of 280 µm
•Then there is a thin coating of Ag in order
to prevent from oxidation of the Cu
•The outer layer of the wire is an
electrically conductive thermoplastic
material
•Melting temperature can be adjusted
between 130°C – 180°C
Ag coating
Cu core
TECC
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – STC Power – SHJ
•Slightly higher FF is achieved for TECC-Wire due to
thicker copper cross section used
•Loss in power for TECC-Wire is only due to lower
current which results from not back reflection of black
colored TECC-Wire in glass/glass modules
Interconnection
technology
Voc
[V]
Isc
[A]
Pmpp
[Wp]
FF
[%]
Vmpp
[V]
Impp
[A]
SmartWire, 22 wires 0.73 8.73 4.95 77.26 0.59 8.45
TECC-Wire, 22 wires 0.73 8.48 4.88 78.53 0.59 8.33
%diff. -0.08 -2.91 -1.40 1.64 0.07 -1.47
TECC-Wire SmartWire
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – TC600
Two group of samples contacted with
18 – 22 TECC wires. per group min. 6
pcs 1-cell modules with BB-less SHJ
solar cells
•Group I: manually-made samples
all samples show a degradation
around 8% after TC100. Afterwards
almost stable up to TC600
•Group II: semi-automated machine
made have reached TC100 with
degradation below 2%
We may have damaged the manually-made cells
during the TECC wire application (see EL picture
below).
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – TC600 EL images
Group I: manually-made samples all samples
show a degradation around 8% after TC100,
then stable until TC600
Group II: semi-automated machine
made samples, degradation below
2% after TC100
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – DH500
Recently made samples
Diagram shows average of 10 busbar-
less SHJ 1-cell modules. Encapsulated
in glass/glass using standard module
materials
The Pmpp degradation after DH500 is
about 2%
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – Industrial Stringing
•We recently ran trials on a commercial XN
CHn40 stringer – side-by side with Bi-based
solder wires using 12BB half-cut solar cell
•TECC-Wire applied on BB 2 + 4
•SnBiAg wire applied on remaining 10 BBs
•Process temperature < 150 °C
•Adhesive force sufficient for both wire types
IEEE PVSC 2021 June 20 – 25, 2021
Status of R&D – Industrial Stringing
Pre-lamination
•Peeled off sample
•TECC-Wire sticks strongly to Ag and to Al on rear of cell
•Even pulling Al off the cell during peel testing
Al
Ag
TECC wire
Cell rear
IEEE PVSC 2021 June 20 – 25, 2021
Outlook: Ag-free PV Industry
Application to TCO layer:
Very uniform EL image (for 22
TECC wires). STC power was
50% only due to poor lateral
conductivity of the TCO layer –
but it conceptually works.
Metallization-free SHJ solar cells
EL image @1A Picture
Voc
[V]
Isc
[A]
Pmpp
[Wp]
FF
[%]
0.71 7.89 2.5 44.3
IEEE PVSC 2021 June 20 – 25, 2021
Summary
•TECC-Wire is a low-temperature (< 200°C) non-soldering solar cell interconnection
technology. Basically, a multi-wire approach with very special wires.
•We see a very good electrical and mechanical contact both to SiN and TCO.
•The recently made reliability test results are promising
•We could demonstrate that also pure TCO surfaces can get contacted
Summary
IEEE PVSC 2021 June 20 – 25, 2021
We are looking for PV producers who are interested in a commercialization.
We are open for any routes into commercialization such as:
•Collaborative R&D work
•Licensing
•Transfer of IP
Call for Collaboration
IEEE PVSC 2021 June 20 – 25, 2021
Solyco Technology GmbH
Baseler Strasse 60
12205 Berlin
Germany
yonas.zemen@solyco.com
+49 179 9833 805
Thank you
IEEE PVSC 2021 June 20 – 25, 2021
ACKNOWLEDGMENTS
This study was supported by a grant from the Federal Ministry for Economy Affairs and Energy on the basis of a decision by
the German government under contract number 0324293H (Project titel: “Dynasto”).