Solar extension cable 40m 4mm² – red/black for efficient PV connections (set)

The solar extension cable set (40 metres, 4mm²) is the specialised solution for photovoltaic projects with extreme distances. If your solar modules need to be positioned in the sunniest spot on the property – e.g. at the end of a very large garden, on a far-away barn or in an open field – and the inverter is to remain centrally located in the building, this set bridges the distance safely and reliably.

The set includes two high-quality, double-insulated solar cables: one red cable for the positive terminal (+) and one black cable for the negative terminal (−). Both ends are professionally pre-assembled with MC4-compatible connectors and sockets. Due to the considerable length of 40 metres (80 metres total run in the circuit), this set is primarily designed for systems with high string voltage, so that the percentage line losses remain within an acceptable range.

Highlights at a glance

• Extreme range: With 40 metres of cable per colour, you can establish far-off setups from the house connection or main distribution panel.
• Plug & play installation: The cables are pre-assembled on both sides with MC4-compatible connectors, so no special crimping tool is required.
• Safe identification: The clear colour coding in red (+) and black (−) efficiently prevents dangerous polarity mistakes along this very long cable run.
• Weatherproof & durable: The special jacket made of crosslinked polyolefin is UV-resistant, ozone-resistant, and withstands extreme temperatures from -40°C to +90°C.
• Protection class IP67: The connectors, when plugged together, are absolutely dust-tight and protected against temporary submersion (e.g. during heavy rain or puddle formation).
• High-quality conductor: Tinned electrolytic copper ensures maximum corrosion resistance and permanently excellent conductivity.

Areas of application

This 40-metre extension is intended for specific scenarios:

• Large ground-mounted systems
  • Ideal for positioning modules far away in the garden or a meadow, where no shadows are cast by buildings or tall trees.
• Outbuildings & agriculture
  • Connecting distant garages, carports, sheds or barns with the main building.
• Indirect cable routing
  • When cables cannot be laid directly but must be routed around the house or through widely branched conduit systems.

Installation & safety instructions

• Voltage drop (Important!)
  • With a length of 40 metres, the total current path is 80 metres. For grid-connected systems with high string voltage (> 120V), 4mm² is still acceptable. For 12V or 24V off-grid systems, this cable is totally unsuitable due to the considerable voltage drop; you would need cross-sections of 16mm² or more.
• Laying in soil
  • Although the cable is weatherproof, it is not protected against mechanical influences (spade blades, rodents). When laying in the ground, a protective pipe (e.g. flexible pipe or cable protection pipe) must be used.
• Avoid induction & heat
  • Never coil surplus cable into a tight roll while current is flowing, as this can cause induction and heat build-up. Lay excess lengths in wide loops ("meanders").

Features

FAQs on the 40m solar extension cable

Is 4mm² really still sufficient at 40 metres in length?

Technically safe for high-voltage systems, but critical for efficiency. With a typical balcony solar system (approx. 40V module voltage, 10A current) you experience a voltage drop of approx. 3.5 volts at 40m. This results in a power loss of around 8.5%. Technically safe, but not really recommended. If you want to optimise yield at this extreme length, you should definitely upgrade to 6mm² or even 10mm² cable.

Will the connectors fit my inverter from Hoymiles, Deye or Growatt?

Yes. The connectors used comply with the worldwide MC4 standard, which is used in almost all modern solar modules and microinverters. They fit mechanically and electrically without any issues.

Can I shorten the cable if necessary?