c1 drafted · lead Cell interconnect ribbon
Covers both the busbars and the string interconnect ribbons; the busbar to string ribbon joint is the most fatigue-prone.
- cell interconnection failure
sec=h4h=3710145a6f87
Cell Interconnection Failure
Cell interconnection failure is a broken or high-resistance joint in the busbars or string ribbons that link the cells in a module. It usually starts with poor soldering or other manufacturing faults, or with transport stress, and gets worse with thermal stress, wind load, hail and corrosion. In early stages series resistance goes up, so fill factor drops and the IV curve knee becomes rounder. When the current is fully blocked, the bypass diode takes over the cell string. You can rarely see it with the naked eye. Use IR thermography to find hotspots, EL imaging to find dark areas at the failed joints, and IV curves to find the loss. Advanced stages can cause burn marks, glass breakage, early bypass diode failure, electric arcs and even fire. Monitor affected modules closely. Replace a module when the failure is electrically active or burn marks are visible.
<!-- review notes
- sentence 1: support check: partial - Busbars and string ribbons are described, and broken or resistive interconnections are mentioned, but no explicit definition as a broken/high-resistance joint. -->
Claims
affects
c2 drafted · lead Bypass diode
When interconnects fully block current, the bypass diode conducts continuously and ages early.
- cell interconnection failure
sec=h7h=14013caaf10f - cell interconnection failure
sec=h5h=5f9cbfc08864
caused_by
c3 drafted · lead Solder bond defect
Poor soldering during manufacturing; it also raises power dissipation and causes local heating.
- cell interconnection failure
sec=h4h=3710145a6f87 - cell interconnection failure
sec=h8h=9f1fbad653f1
c4 drafted · lead Manufacturing defect
Misplaced ribbons, an over-deformed ribbon kink, too little spacing between cells, and the lamination process.
- cell interconnection failure
sec=h4h=3710145a6f87
c5 verified · fact Transport damage
Mechanical stress during transportation.
- cell interconnection failure
sec=h4h=3710145a6f87
verified by: joshuahamsaverified on: 2026-10-16
c6 drafted · lead Thermal cycling
Thermomechanical stress in operation fatigues the interconnections.
- cell interconnection failure
sec=h4h=3710145a6f87
c7 drafted · lead Repetitive wind load
- cell interconnection failure
sec=h4h=3710145a6f87
c8 verified · fact Hail impact
- cell interconnection failure
sec=h4h=3710145a6f87
verified by: joshuahamsaverified on: 2026-10-16
c9 drafted · lead Severe Metallization Corrosion
Corrosion of the cell metallization fatigues the interconnects; it often shows as light yellow to dark discoloration of the electrical parts.
- cell interconnection failure
sec=h7h=14013caaf10f - cell interconnection failure
sec=h4h=3710145a6f87
c10 drafted · lead Moisture exposure
A defective or detached junction box can let humidity in, which increases corrosion and weakens the interconnects.
- cell interconnection failure
sec=h7h=14013caaf10f
c11 drafted · lead Partial shading
Hotspots from partial shading add thermomechanical stress and fatigue to the interconnects.
- cell interconnection failure
sec=h7h=14013caaf10f
presents_as
c12 drafted · lead Hotspot in IR image
- cell interconnection failure
sec=h8h=9f1fbad653f1
c13 verified · fact Dark regions in EL image
The darker regions appear at the failed interconnects.
- cell interconnection failure
sec=h8h=9f1fbad653f1
verified by: joshuahamsaverified on: 2026-10-16
c14 drafted · lead Increased series resistance
Stage 1: only a few interconnects are disconnected.
- cell interconnection failure
sec=h8h=9f1fbad653f1 - cell interconnection failure
sec=h5h=5f9cbfc08864
c15 drafted · lead Reduced fill factor
- cell interconnection failure
sec=h5h=5f9cbfc08864
c16 drafted · lead Distorted IV curve shape
The knee of the IV curve becomes more rounded.
- cell interconnection failure
sec=h8h=9f1fbad653f1
c17 verified · fact Bypassed substring
Once failures block current, the bypass diode activates and the cell string is bypassed.
- cell interconnection failure
sec=h8h=9f1fbad653f1 - cell interconnection failure
sec=h5h=5f9cbfc08864
verified by: joshuahamsaverified on: 2026-10-16
c18 drafted · lead Burn marks
Appears in advanced stages.
- cell interconnection failure
sec=h8h=9f1fbad653f1 - cell interconnection failure
sec=h7h=14013caaf10f - cell interconnection failure
sec=h5h=5f9cbfc08864
leads_to
c19 drafted · lead Glass Breakage
Appears in advanced stages.
- cell interconnection failure
sec=h7h=14013caaf10f - cell interconnection failure
sec=h5h=5f9cbfc08864
c20 verified · fact Bypass Diode Failure
Continuous bypass operation ages the diode early. An open-circuited diode then forces current through the failed string.
- cell interconnection failure
sec=h7h=14013caaf10f
verified by: joshuahamsaverified on: 2026-10-16
Arcing can occur if the bypass diode does not work correctly; fire is possible.
- cell interconnection failure
sec=h7h=14013caaf10f - cell interconnection failure
sec=h5h=5f9cbfc08864
detected_by
c22 verified · fact Electroluminescence imaging
- cell interconnection failure
sec=h2h=cc879c2d8fb5 - cell interconnection failure
sec=h8h=9f1fbad653f1 - Quantification of Technical Risks in PV Power Systems
tbl=33.r2h=dad17d1f52d0
verified by: joshuahamsaverified on: 2026-10-16
c23 drafted · lead Infrared thermography
- cell interconnection failure
sec=h2h=cc879c2d8fb5 - cell interconnection failure
sec=h8h=9f1fbad653f1 - Quantification of Technical Risks in PV Power Systems
tbl=33.r2h=dad17d1f52d0
c24 drafted · lead IV curve tracing
- cell interconnection failure
sec=h2h=cc879c2d8fb5 - cell interconnection failure
sec=h8h=9f1fbad653f1
c25 drafted · lead Visual inspection
Hard to see with the naked eye; visible mainly through burn marks or glass breakage in advanced stages.
- cell interconnection failure
sec=h2h=cc879c2d8fb5 - cell interconnection failure
sec=h8h=9f1fbad653f1 - Quantification of Technical Risks in PV Power Systems
tbl=33.r2h=dad17d1f52d0
c26 drafted · lead UV fluorescence imaging
UV imaging can detect ribbon breakages.
- cell interconnection failure
sec=h8h=9f1fbad653f1
c27 verified · fact Signal transmission method
A low-cost method.
- cell interconnection failure
sec=h8h=9f1fbad653f1 - Quantification of Technical Risks in PV Power Systems
tbl=33.r2h=dad17d1f52d0
verified by: joshuahamsaverified on: 2026-10-16
mitigated_by
c28 drafted · lead Module replacement
Advised when the failure is electrically active, in advanced stages, or when burn marks are visible.
- cell interconnection failure
sec=h2h=cc879c2d8fb5 - cell interconnection failure
sec=h8h=9f1fbad653f1
c29 verified · fact Close monitoring
- cell interconnection failure
sec=h8h=9f1fbad653f1
verified by: joshuahamsaverified on: 2026-10-16
c30 drafted · lead Mechanical stress reduction
- cell interconnection failure
sec=h2h=cc879c2d8fb5
c31 verified · fact Thermal stress reduction
- cell interconnection failure
sec=h2h=cc879c2d8fb5
verified by: joshuahamsaverified on: 2026-10-16
typical_power_loss
c32 verified · fact nominal 0.1 PERCENT
Conditions: Per interconnection cut in cells with 4 busbars (Colvin et al.); series resistance rises by about 1%
- cell interconnection failure
sec=h5h=5f9cbfc08864
verified by: joshuahamsaverified on: 2026-10-16review note: possible conflict with c33 (same source; check the conditions)
c33 verified · fact nominal 1 PERCENT
Conditions: Per interconnection cut in cells with 3 busbars, which have less redundancy (Annigoni et al.)
- cell interconnection failure
sec=h5h=5f9cbfc08864
verified by: joshuahamsaverified on: 2026-10-16review note: possible conflict with c32 (same source; check the conditions)
Referenced by
- Arc fault
caused_byc1 - Glass Breakage
caused_byc16 - Hot cell
leads_toc12 - Junction Box Failure
leads_toc25 - Module Hotspot from Cell Damage
leads_toc20 - Severe Metallization Corrosion
leads_toc21