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Abbreviations/Acronyms
Cable standards for PV cables
Standards by definition are ‘a quality that is consid-
ered acceptable or desirable’.
Two agencies which have approvals for solar
cables in the USA are the Underwriters Laboratory
(UL) and the National Electric Code (NEC). The two types
of approvals for Photo-Voltaic cables are USE-2 and type PV.
The Technischer Uberwachung- Verein (TUV) – Germany and this
has approvals based on the ISO 4892 [1], EN50395 [2] and EN50396
[3] all being tested according to IEC 60811 [4].
Only PV cables of a quality that is considered acceptable or desir-
able in accordance with the recognised standards can therefore be
used in solar installations as a mere baseline requirement.
Concept of cable protection against external influ-
ences
For the purposes of this article, the external influences that affect
the protection of PV cables are considered. The life of PV cables is
generally twenty five (25) years or more, but being exposed to harsh
environmental conditions can subsequently damage unprotected
cables. The concept of cable protection starts with the cable selec-
tion in accordance with acceptable standards and the progress to
the installation process in accordance with a recommended cable
management standard.
Protection of cables from sunlight and heat
Cables that are used in PV installations are rated as Ultra Violet (UV)
resistant or simply that they can withstand high temperature ranges
fromas low as -60°C up to as high as 90°C. Although the insulation and
jacket materials that surround the conductors are extremely resistant
to UV radiation, the underlying fact is that they must be kept from
direct sunlight exposure as much as possible. With continuous direct
sunlight exposure the cables suffer degradation causing damage.
By also selecting the correct colour for the PV outdoor cable which
is ‘Black’ (containing carbon black in its insulation), the cable will
be provided with additional UV resistance. Unprotected PV cables
from direct sunlight or high ambient temperature results in the cable
becoming brittle or breakable.
CABLES + ACCESSORIES
Protection of cables from direct sunlight can be
achieved by implementing a safe, reliable and code
compliant wire management system. By conveni-
ently using the available shade of the modules and
other structural members, one can improve on the life
of PV cables. The PV cables can be protected by being
secured to the module frames, support rails and other rack-
ing system components. Where cables are exposed away from the
panel covering (where inter row PV cable routing occurs), they can
be provided with a special protective covering.
Protection of PV cables from heat sources can be achieved by
not fixing the cables within sixinches from the heat source. Another
method to protect the PV cables from such a heat source is by ad-
equately shielding the cable and its protective sheathing or properly
selecting a PV cable of special design (heat resistant cable) to with-
stand the effects of such exposure.
Cable trays’ systems can also be used in lengths of the panel ar-
rangements where PV cables run along the trays under the modules.
All standard requirements must be adhered to when implementing
these installations. In addition to trays, PVC or galvanised metal
conduits can be used to protect the solar cables.
Protection of PV cables from water
PV cables should not be in constant contact with water as this may
cause the cables to be saturated with water. Persistent water satura-
tion can lead to insulation resistance damage and even rotting of
cables causing short circuits and earth leakages.
Cables which can be subjected to such conditions must be care-
fully selected in accordance with the acceptable standards. The cable
selection must ensure that the cable used is for outdoor use and can
be used in wet conditions.
In order to prevent or protect cables from water damage due to
constant water logging, shading and elevating of PV cables in sealed
channels and conduits. For PV cables underground the same princi-
ple of sealing exposed ends of conduits or sleeves will alleviate the
saturation of cables with water.
To protect the PV cables from water in general they shall not be
fixed (if possible) where they will be exposed to the accumulation of
water which might damage the conductor or its protective covering
NEC
– National Electric Code
PV
– Photovoltaic
PVC
– Polyvinyl chloride
TUV
– Technischer Uberwachung-Verein
UL
– Underwriters Laboratory
UV – Ultraviolet
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October ‘16
Electricity+Control