Solar cables are central to photovoltaic (PV) systems – many errors arise from incorrect installation. This article helps installers with correct installation, but is not a substitute for checking legal regulations.
Why correct installation is important!
In a PV system, solar cables are designed to transfer energy from the solar modules to the inverter. If their functionality is negatively affected by incorrect installation, this will directly impact the PV system's performance. In the worst case, the system may have to be shut down.
There are other reasons why correct installation of solar cables is important:
Compliance with standards and regulations
Only with correctly installed solar cables will the PV system comply with applicable regulations (e.g., DIN VDE 0100, IEC 60364) and be successfully accepted at the end of installation. This is crucial for obtaining full insurance coverage.
Tip:KBE solar cables are triple-certified according to the European standard EN 50618 (H1Z2Z2-K), the international solar cable standard IEC 62930 (IEC 131), and the standard 2Pfg 1169 /10.2019 (PV 1500-K).
Ensure safety
Fire protection: Faulty or improperly installed cables can cause overheating or short circuits, which in the worst case can lead to a fire.
Protection against electric shock: Proper installation prevents cables from being damaged and dangerous voltages from being released.
Get full performance
Minimize power losses: Correct cable cross-sections and short cable runs reduce resistance losses. This allows more energy to be fed into the grid.
Prevent voltage drops: Optimal installation prevents voltage drops, allowing the system to run efficiently.
Maintain weather resistance and longevity
UV and weather protection: Solar cables are often exposed to direct sunlight. Improper installation causes them to become brittle more quickly.
Mechanical protection: Failure to protect solar cables from animals (e.g., rodents) and external influences can result in damage and performance losses to the PV system.
Easier maintenance and troubleshooting
A clean, well-thought-out installation facilitates subsequent inspections and repairs, saving time and money.
Before laying: select the correct cable length!
To minimize power losses, cable runs should be kept as short as possible.
Cables should not be laid too tightly.
Legal regulations regarding fire protection and the safety of electrical installations must be observed.
Related standard: EN 62548 “Cables must be installed in such a way that wind or snow do not cause permanent damage.” Reason: The swinging of a cable coil can lead to abrasion at the support point.
General information about solar cables
Solar cables in PV systems must meet the requirements of EN 50618.
The materials used for these cables are selected to withstand ambient temperature fluctuations from -40 °C to 90 °C and to be resistant to UV radiation.
The expected service life is 25 years.
General information on laying solar cables
Solar cables must always be installed and laid with the utmost care to avoid mechanical damage.
Installation should only be carried out at temperatures above -20 °C.
Ensure that the cable and line routes are protected from unauthorized access.
No kinks or loops may form during installation.
Cables must always be secured/tied up.
Cables must not be laid directly on the roof surface (DIN VDE 0100-712).
Use conduits or cable routing systems if solar cables are to be laid in bundles.
Cables must not be routed over sharp-edged areas when cable routing systems (ducts, conduits) are used.
It must be ensured that water (e.g., condensate) can escape from the cable routing systems.
To provide protection from the weather (water and UV radiation), install cables in rails – if possible.
The rails should be perforated to allow rain or condensation to drain away.
If the module transitions are located in a sunny area, the cables should be protected against UV radiation.
If there is an increased risk of animal bites, the cables should be installed in pipes or cable ducts. Or use the KBE Solar DB+ TR-AR solar cable.
Avoid contact with aggressive substances! This will preserve the mechanical and electrical properties and reduce corrosion damage.
The maximum tensile force during installation is FP = σ A, where σ = 15 N/mm² and A is the nominal conductor cross-section.
Laying with other circuits
As a general rule, solar cables should always be laid separately from other circuits.
If wires and cables from different circuits are to be laid together in conduits or cable ducts, you must observe EN 62548 (Section 7) or DIN VDE 0100-520.
DIN VDE 0100-520: "Multiple circuits are permitted in one conduit or in one openable conduit if all conductors are insulated for the highest nominal voltage occurring and the conduits or openable conduits have sufficient cross-sections."
The correct fastening of solar cables
Use fastening clips or cable ties (wide and UV-resistant) to properly secure the cables.
When using cable ties, please follow the manufacturer's instructions regarding tightening forces.
Avoid sharp edges when fastening.
Photovoltaic clips are suitable for attaching solar cables to metal rails.
Permissible bending radii and fastening distances according to EN 50565-1 must be observed:
The smallest recommended bending radius:
4 mm²
6 mm²
10 mm²
freely movable
22 mm
24 mm
29 mm
permanently installed
17 mm
18 mm
22 mm
mechanically stressed
33 mm
36 mm
43 mm
Maximum mounting distances:
4 mm²
6 mm²
10 mm²
horizontal
250 mm
250 mm
250 mm
vertical
400 mm
400 mm
400 mm
Pay attention to the correct installation method!
Earth-fault and short-circuit-proof installation
Minimize the risk of ground faults and short circuits. Observe DIN VDE 0100-712.
Attach solar cables properly to the solar module:
e.g., the connector should not rest on the roof surface.
Lay solar cables in a way that protects them from water.
Do not lay solar cables in places where rainwater collects.
Related standard: DIN VDE 0100-712, section 712.521.101
Parallel laying
Solar cables should be laid parallel to each other if possible.
To avoid interactions, the positive and negative cables should be laid separately in ducts.
In accordance with DIN EN 62548, the following should be observed for solar cables with a length of > 50 m:
Install in grounded metal conduits or ducts, or
bury (follow guidelines), or
provide a grounded shield, or
protect with a surge protective device (SPD).
Related standards:
DIN VDE 0100-712, Section 712.521.102: "To minimize voltages induced by lightning, the area of all cable and conductor loops should be kept as small as possible, especially in the cabling of PV strings."
EN 62548, Paragraph 6.6.2: "Solar cables and the equipotential bonding conductors must be laid as parallel as possible."
Underground laying
Mechanical stress on the buried cable must be eliminated.
To protect against rodents and insects, the cables should be installed in pipes or cable ducts. Alternatively, use the KBE Solar DB+ TR-AR solar cable.
Contact with aggressive media, which reduces the mechanical and electrical properties, must be eliminated.
When installing different cable types, the compatibility of the materials used must be ensured.
When selecting cable and line routes, heat sources and vibrations that increase the risk of damage must be eliminated.
Related standards:
DIN VDE 50174-1 Section 5.2.4 and DIN VDE 0891 Part 6 Section 4.2: "Installation on a solid, smooth, and stone-free trench bottom and bedding in sand or stone-free soil."
