Solar extension cable 25m 4mm² - red/black for efficient PV cabling (set)

The solar extension cable set (25 metres, 4mm²) is the solution for photovoltaic projects with extreme distances. If your solar modules need to be located in the sunniest place on the property – for example at the end of a large garden, on a distant barn or in an open field – and the inverter is to remain centrally in the house, this set bridges the distance safely and reliably.

The set includes two high-quality, double-insulated solar cables: one red cable for the positive pole (+) and one black cable for the negative pole (-). Both ends are professionally pre-assembled with MC4-compatible plugs and sockets. Due to the considerable length of 25 metres, this set is primarily designed for systems with a higher string voltage (e.g. several modules in series or grid-connected balcony power plants) in order to keep line losses low.

Highlights at a glance

• Maximum range: With a length of 25 metres (50 metres in the circuit) you can also implement complex installation scenarios far from the house connection.
• Plug & Play installation: The cables are pre-assembled on both sides with MC4-compatible connectors, so no special crimping tool is required.
• Secure identification: The colour coding in Red (+) and Black (-) effectively prevents polarity mix-ups with such a long cable run.
• Weatherproof & durable: The special jacket made of cross-linked polyolefin is UV-resistant, ozone-resistant and withstands extreme temperatures from -40°C to +90°C.
• Protection class IP67: When plugged in, the connectors are completely dustproof and protected against temporary submersion (rain/puddles).
• High-quality conductor: Tin-plated electrolytic copper ensures corrosion resistance and consistently good conductivity.

Areas of application

This 25 metre extension is intended for specific scenarios:

• Ground-mounted systems: Ideal for installing modules far away in the garden or on a meadow where there is no shading from buildings.
• Outbuilding: Connection of distant garages, carports, sheds or stables to the main building.
• Indirect cable routing: When cables cannot be laid directly, but have to be routed around the entire house or through long empty conduits.

Installation & Safety Instructions

• Voltage drop (Important!): At 25 metres length, the total current path is 50 metres.
  • For grid-connected systems (voltage > 30V) 4mm² is usually acceptable (loss approx. 3-5%).
  • For 12V off-grid systems this cable is not suitable, as the voltage drop would be too high. Here, 10mm² or 16mm² would have to be used.
• Laying in the ground: Although the cable is weatherproof, it is not protected against mechanical influences (stones, rodents, spades).
  • When laying underground, it is essential to use a protective conduit (KG conduit or flexible conduit).
• Avoid induction: Never wind excess cable into a coil while current is flowing, as this can lead to heat buildup.
  • Lay excess lengths in wide loops ("meanders").

Properties

FAQs about the solar extension cable 25m

Is 4mm² really sufficient at 25 metres length?

Yes for high-voltage systems, no for 12V systems. With a typical balcony power plant (approx. 30-40V module voltage, approx. 10A current) you will have a voltage drop of approx. 2 volts. This means a power loss of about 4-5%. This is technically safe, but not optimal. If you need every watt, you should upgrade to 6mm² cable at this length. For a 12V battery application, almost 1 volt would be lost – that's too much!

Will the connectors fit my inverter from Hoymiles or Deye?

Yes. The connectors used correspond to the MC4 standard, which is used for almost all solar modules and micro inverters worldwide. They fit mechanically and electrically perfectly.

Can I shorten the cable?