Difference Between Armoured and Unarmoured Solar Cables
Armoured solar cable carries a layer of galvanised steel or aluminium wire under the outer sheath to resist crushing, digging and rodent damage. Unarmoured cable does not. Use unarmoured H1Z2Z2-K for rooftop DC string runs in conduit or tray. Use armoured SWA cable for anything buried, run across open ground, or exposed to vehicles.
Renewable energy sources are grasping the attention of nations across the world. Since it is the optimal way to generate power without impacting the environment, there are lots and lots of innovations introduced in the renewable industry, especially solar. One of the crucial elements of solar power systems is cabling. Solar cables are specialised electrical cables that are useful in interconnection in solar power systems. These cables connect solar panels to other solar panels and system components such as batteries, inverters, charge controllers, and electrical components.Â
The choice of the right solar cables plays an essential role in seamless, efficient and reliable power transmission. Below we set out the differences between armoured and unarmoured solar cables, when to specify each, and what the difference actually costs.
Armoured Solar cables
Armoured solar cables come with an extra layer of protection intended to protect them from physical damage and the environment. Typically, this additional layer is built using plastic or metal and it surrounds the cable core. The armoured cables can be made up of various materials such as copper, aluminium, etc. Armoured solar cables are packed into metal sleeves and processed into a solid combination that you can bend.
Solar armoured cable is normally supplied as steel wire armour (SWA) or aluminium wire armour (AWA). SWA is used on multi-core cable, where the magnetic fields of the individual cores largely cancel each other out. AWA is used on single core AC runs, because steel armour surrounding a single conductor carrying alternating current induces circulating currents in the armour itself, which heats the cable and wastes energy. Specifying steel armour on single core AC is one of the most common and most expensive mistakes on ground mount projects, and it presents as a thermal fault that can take weeks to trace.
Applications of armoured solar cables
- Armoured solar cables are widely used in buried environments, cable trench laying or direct burial requirements.
- Armoured cables are installed in locations that can be exposed to mechanical damage. This covers environments such as the outsides of walls.
- Ground mount arrays, on any run where the cable leaves the table structure and crosses open ground. In much of the Middle East, East Africa and South Asia this is driven by rodent and termite damage rather than by impact risk.
- Car park canopies, walkways, and any route within reach of vehicles or pedestrians.
Unarmoured solar cables
Those cables without steel or aluminium armour protection are referred to as unarmoured solar cables, or non-armoured cables.
The standard DC cable used in photovoltaic systems is H1Z2Z2-K, manufactured to EN 50618 and IEC 62930. It is a single core cable with a tinned copper conductor, cross-linked polyolefin insulation and sheath, rated to 1.5 kV DC and to an operating range of minus 40 to plus 90 degrees Celsius, with a UV-resistant service life of 25 years.
Insist on tinned copper rather than bare copper. In hot, humid or coastal environments bare copper oxidises at the termination and contact resistance rises steadily across the life of the plant. The cost difference at purchase is small. The cost difference at year twelve is not.
Applications of unarmoured solar cables
- Rooftop DC string runs, routed in cable tray or conduit. This is the default specification for rooftop, and the case where armour adds cost, weight and bending radius for no measurable benefit.
- DC runs within the ground mount table structure, before the cable leaves the array.
- Any run where the cable is mechanically protected by the containment system rather than by the cable itself.
Differences between armoured and unarmoured solar cables
| Property | Unarmoured (H1Z2Z2-K) | Armoured (SWA / AWA) |
|---|---|---|
| Standard | EN 50618, IEC 62930 | IEC 60502-1, BS 5467 |
| Typical use | DC string runs, rooftop, in tray or conduit | Buried runs, AC feeders, ground mount, exposed routes |
| Voltage rating | 1.5 kV DC | 600 / 1000 V AC |
| Mechanical protection | Sheath only | Steel or aluminium wire armour |
| Rodent and termite resistance | Poor | Good |
| Bending radius | Tight, easy to route | Large, needs planning |
| Termination | Standard MC4 or lug | Brass gland required at every entry |
| Relative cost per metre | Baseline | [X] percent more, before glands |
| Installation labour | Low | Higher |
Structure
Armoured – The additional outer protective layer of armoured cable is typically made of steel tape or steel wire, and it protects the cable from external mechanical damage. This extra protective layer also safeguards the cables against bites of rats and termites. The bending radius of the armoured cable is large.
The sheath is the only mechanical protection. That makes the cable lighter, far easier to route, and much tighter in bending radius, which is why it is the correct choice inside tray, conduit and the array structure. It also means the cable relies entirely on its containment for protection, so the containment specification matters more than it does with armoured cable.
Cost
Armoured: Typically [X] percent more per metre than the equivalent unarmoured cable. The metre rate understates the real difference, because every cable entry requires a brass gland, and installation takes longer due to the bending radius and the additional support required. Budget the glands and the labour, not just the drum.
Unarmoured: Baseline cost. There is no armour layer to manufacture, the cable is lighter to transport, and it is faster to install and terminate using standard MC4 connectors or lugs.
What this means in practice: On a typical rooftop project, specifying armoured cable where unarmoured is appropriate adds cost to the DC scope without reducing any real risk. On a ground mount project, specifying unarmoured where the cable crosses open ground saves a small amount at build and creates a fault that is expensive to locate and expensive to repair.
Sizing by run length
Armour does not change the conductor size you need. Voltage drop does. Work to these targets:
| Section | Voltage drop target |
|---|---|
| Individual string to combiner | Under 1 percent |
| Total DC, array to inverter | Under 2 percent |
| AC, inverter to point of connection | Under 3 percent |
Long DC runs are where projects quietly lose yield. A 2 percent drop across the DC side is 2 percent of generation gone for the life of the plant, and it never presents as a fault, so nobody investigates it. It is always cheaper to increase conductor size at build than to accept the loss across 25 years.
Buried cable also derates. Installation method, soil thermal resistivity, burial depth and grouping all reduce the current a cable can safely carry. Size against the installation methods set out in IEC 60364-5-52, not against the free-air rating printed on the datasheet.
Calculate against your actual run lengths, string current and ambient temperature. Do not size from a general table, including this one.
When to specify armoured, and when not to
Most specifications in this region over-specify armour on the DC side and under-specify it on the ground.
Armouring a rooftop string run adds cost, weight and installation time to protect against a risk that is not present on a roof. Meanwhile the run that genuinely needs protection, the one crossing open ground between the array and the inverter room, is often specified as unarmoured because it was drawn as part of the DC scope rather than assessed for exposure.
Our position: specify by exposure, not by scope boundary. Unarmoured on the roof and inside the table structure. Armoured the moment the cable touches ground, leaves the structure, or enters a trench. That splits the bill of materials sensibly and puts the money where the failure mode actually is.
Where armour is the right call, it earns its cost. The mechanical protection layer of armoured cables can be added to any cabling structure and this helps in increasing the mechanical strength of the solar cables. Ultimately, they help achieve improved erosion properties and are best suited for areas that are exposed to mechanical damage and erosion.
Since the armoured solar cables have extra layers, they enrich tensile strength, and compressive strength, eventually leading to extended service life. The armoured cables possess resistance to external forces.
One further point on earthing. Do not rely on the armour as the protective earth conductor without a calculation. It can serve that function under some regimes, but the adiabatic check has to be run against the actual fault level, and on long runs it frequently fails. Run a separate earth conductor unless the calculation says otherwise.
Standards to specify against
Quote these by number in your specification so there is no ambiguity at tender:
- EN 50618 / IEC 62930. DC cable for photovoltaic systems, H1Z2Z2-K
- IEC 60502-1. Power cables with extruded insulation, 1 kV to 3 kV
- BS 5467. Armoured cables with thermosetting insulation, 600 / 1000 V
- IEC 60228. Conductor classes for insulated cables
- IEC 60364-5-52. Selection and erection of wiring systems, including installation methods and derating
- IEC 60332-1. Flame propagation
- IEC 60754. Halogen-free performance
- IEC 61034. Smoke density
Conclusion
Solar cables are recognised for a service life of up to 30 years, and they offer reliable performance across that period provided they are correctly specified for the environment they sit in.
Armoured solar cables with the additional protection layer are designed to withstand harsh conditions, and they deliver protection from physical damage that makes them the right choice for buried, exposed and hazardous routes. Unarmoured H1Z2Z2-K remains the correct choice for protected rooftop and in-structure runs. The decision is made by exposure, not by preference.
Frequently asked questions
Not directly. Un-armoured cable in direct contact with soil will eventually fail from crushing, moisture ingress or rodent damage, and it will fail somewhere you cannot see. Inside continuous rigid duct it is acceptable, provided the duct is genuinely unbroken along the full route and recorded on the as-built drawing.
No. Armour is mechanical protection and has no effect on conductivity. Efficiency comes from conductor cross-section and run length. On single core AC runs, steel armour actively reduces efficiency through circulating currents, which is why aluminium wire armour is specified instead.
Generally no. Rooftop DC runs in tray or conduit are correctly specified as unarmoured H1Z2Z2-K. Armour becomes necessary where the cable leaves the roof and runs at ground level or enters a trench.
Yes, and it should be on buried and exposed DC runs. Confirm the DC voltage rating before ordering, because standard 600 / 1000 V AC armoured cable is not rated for 1.5 kV DC systems.
How much more does armoured cable cost?
Typically [X] percent more per metre, but the metre rate understates it. Every cable entry needs a brass gland and installation takes longer because of the bending radius and support requirements. Budget the glands and the labour, not just the drum.
Buy APAR’s E-Beam Irradiation Technology Solar cables
Power & Sun is delighted to bring you the Electron Beam irradiation armoured solar DC cables from APAR that are best known for their outstanding performance in demanding applications and harsh environments. This E-beam irradiation technology from the brand ensures improved cross-linking and polymer modification for the solar cables, still, the process doesn’t release any harmful chemical by-products. The cables are highly capable of withstanding high temperatures of up to 105˚C, safe, and are ideal for high-end and safety projects.
