Cable Defect

ID: fm:cable-defect
IRI: https://solarlattice.org/kb/fm/cable-defect
Status: active
Category: Wiring

A cable defect is damage to the DC cabling that connects the parts of a PV array, and it is rated as a high-severity failure. Common causes are poor cable materials, undersized cables or weak UV protection chosen at the design stage, and poor installation, such as routing over sharp edges or bending cables too tightly. Damaged cables can look melted, burned, brittle, cracked or whitened, and they may show corrosion or animal bites. The defect can cause insulation and ground faults, open string circuits with large power loss, higher series resistance with extra heat, and arcs that can start a fire. Insulation faults may come and go with humidity, and they can stay hidden if the leakage current is below what the protection devices react to. To confirm the fault, do a visual inspection and an infrared inspection, test insulation resistance, compare string currents, and locate the fault on isolated circuits.

Claims

`affects`

c1 drafted · lead DC cable

Cables run across the whole array and connect its elements.

cable defect sec=front h=b8e06ac4915e
cable defect sec=h3 h=24187737e6d1

`caused_by`

c2 drafted · lead Undersized component

Undersized cables chosen at the design stage.

cable defect sec=front h=b8e06ac4915e
cable defect sec=h2 h=ecd061f4ac98
Quantification of Technical Risks in PV Power Systems tbl=45.r3 h=091be96f279b
Degradation and Failure Modes in New PV Technologies – Annex tbl=27.r3 h=091be96f279b

c3 verified · fact Low-quality material

Poor insulation material or copper wire used in cable production.

Quantification of Technical Risks in PV Power Systems tbl=45.r3 h=091be96f279b
Degradation and Failure Modes in New PV Technologies – Annex tbl=27.r3 h=091be96f279b

verified by: joshuahamsaverified on: 2026-10-16

c4 verified · fact Installation error

Improper handling or fixing during installation, e.g. cables hanging near connections or missing fixings.

Quantification of Technical Risks in PV Power Systems tbl=45.r3 h=091be96f279b
Degradation and Failure Modes in New PV Technologies – Annex tbl=27.r3 h=091be96f279b

verified by: joshuahamsaverified on: 2026-10-16

c5 drafted · lead Mechanical stress

Routing over sharp or abrading edges and bending too tightly.

Quantification of Technical Risks in PV Power Systems tbl=45.r3 h=091be96f279b
Degradation and Failure Modes in New PV Technologies – Annex tbl=27.r3 h=091be96f279b
cable defect sec=front h=b8e06ac4915e

c6 drafted · lead UV exposure

Design choices with inadequate UV protection or IP class; exposed wiring needs UV protection.

Quantification of Technical Risks in PV Power Systems tbl=45.r3 h=091be96f279b
Degradation and Failure Modes in New PV Technologies – Annex tbl=27.r3 h=091be96f279b
cable defect sec=front h=b8e06ac4915e

review note: support check: partial - Inadequate UV protection in design is cited as a cause, but UV exposure as a stressor is only implied.

c7 verified · fact Animal activity

Animal bites on cables are shown.

cable defect fig=1 h=7ede5cd7e80d

verified by: joshuahamsaverified on: 2026-10-16

`leads_to`

c8 verified · fact Loss of electrical insulation

Insulation fault is a main cable defect; it can be intermittent depending on humidity, and if leakage stays below protection-device ratings it can go undetected.

cable defect sec=front h=b8e06ac4915e
cable defect sec=h2 h=ecd061f4ac98
cable defect sec=h6 h=2f6cadabed98

verified by: joshuahamsaverified on: 2026-10-16

c9 drafted · lead Arc fault

Damaged cables can produce electric arcs that may cause fire.

cable defect sec=h6 h=2f6cadabed98

`presents_as`

c10 verified · fact Ground fault alarm or trip

cable defect sec=front h=b8e06ac4915e
cable defect sec=h2 h=ecd061f4ac98

verified by: joshuahamsaverified on: 2026-10-16

c11 verified · fact Open string circuit

An open wiring circuit causes significant string-level power loss.

cable defect sec=h6 h=2f6cadabed98

verified by: joshuahamsaverified on: 2026-10-16

c12 verified · fact Reduced string current

cable defect sec=h6 h=2f6cadabed98
cable defect sec=front h=b8e06ac4915e

verified by: joshuahamsaverified on: 2026-10-16review note: support check: partial - String-level power losses and string current comparison are mentioned, but reduced string current output isn't explicitly stated.

c13 drafted · lead Increased series resistance

Early corrosion raises series resistance, so more power is dissipated as heat.

cable defect sec=h6 h=2f6cadabed98

c14 drafted · lead Visible corrosion marks

cable defect fig=1 h=7ede5cd7e80d
cable defect sec=h6 h=2f6cadabed98

review note: support check: partial - A corroded cable is shown in the figure, but corrosion as a visible symptom is not explicitly stated for cables.

c15 verified · fact Melted component