Cable specified for photovoltaic use: rated for ultraviolet exposure, for a wide temperature range and for double insulation, with a conductor sized for the current and the run. Ordinary flexible cable degrades outdoors in a way that is invisible until it fails.
Solar cable is a specified product rather than a colour of flex, and the specification is about the environment rather than the current.
What the rating covers
Resistance to ultraviolet light, a temperature range that spans a cold night and a hot roof, and insulation suited to a direct-current system that is live whenever the sun is up. Double-insulated construction is the usual form.
Why the conductor is often tinned
Tinned strands resist corrosion where moisture can reach them, which on an outdoor run is eventually everywhere. It is standard in marine practice and common on quality solar cable for the same reason.
Sizing, which is the same everywhere
Current, run length and acceptable voltage drop, remembering that a long roof-to-controller run at panel voltage behaves better than the same run at battery voltage — which is one of the arguments for wiring panels in series.
What is attached at each end
Connectors crimped with the right die, housings mated with their own kind, and cable supported so it does not chafe on a roof edge or hang on its connectors. Mechanical support is not a detail: on a long-lived installation it is the thing that usually fails first.
What people ask before they order
What actually happens to ordinary cable outdoors?
Ultraviolet light embrittles the sheath, and temperature cycling cracks it. The conductor is unaffected until moisture reaches it, which is why the failure appears suddenly after a long apparently healthy period.
Does the colour indicate polarity?
Not reliably — solar cable is commonly sold in black for both poles, with polarity carried at the connector. That is a deliberate convention and it is why the connector housings are keyed.
Last reviewed 16 September 2026