Solar extension cable

The Solar extension cable set (25 metres, 4 mm²) is the solution for photovoltaic projects involving extreme distances. If your solar panels need to be positioned in the sunniest spot on your property – for example, at the far end of a large garden, on a distant barn or out in an open field – and the inverter is to remain centrally located in the house, this kit allows you to bridge the distance safely and reliably.

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

Highlights at a glance

• Maximum range: With a length of 25 metres (50 metres in the circuit), you can also set up complex installations far away from the domestic connection.
• Plug & Play installation: The cables are pre-fitted with MC4-compatible connectors at both ends, so no special crimping tools are required.
• Reliable identification: The colour coding in Red (+) and Black (-) effectively prevents polarity mix-ups over such a long installation run.
• Weatherproof & durable: The special cross-linked polyolefin sheath is UV-resistant, ozone-resistant and withstands extreme temperatures ranging from -40°C to +90°C.
• IP67 protection rating: When connected, the connectors are completely dust-tight and protected against temporary submersion (rain/puddles).
• High-quality conductor: Tinned 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 in a field, where there is no shade cast by buildings.
• Outbuildings: Connecting garages, carports, sheds or stables located some distance away from the main building.
• Indirect cable routing: If cables cannot be laid directly, but have to be routed around the entire house or through long conduit systems.

Installation & safety instructions

• Voltage drop (Important!): With a length of 25 metres, 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. You would need to use 10 mm² or 16 mm² here.
• Laying the cable in the ground: Although the cable is weatherproof, it is not protected against mechanical damage (stones, rodents, spades).
  • When laying the cable underground, you must use a protective conduit (KG conduit or flexible conduit).
• Avoid induction: Never wind excess cable into a coil whilst electricity is flowing, as this can cause the cable to overheat.
  • Lay any excess length in wide loops (“meandering”).

Features

FAQs on the 25m solar extension cable

Is 4 mm² really sufficient for a length of 25 metres?

Yes for high-voltage systems, no for 12V systems. With a typical balcony solar system (approx. 30–40 V module voltage, approx. 10 A current), you will experience a voltage drop of approx. 2 volts. This equates to a power loss of around 4-5%. Whilst this is technically safe, it is not ideal. Anyone who needs every watt should, given this length, opt for 6mm² cable upgrade. In a 12V battery application, you would lose almost 1 volt – that’s too much!

Will the connectors fit my inverter from Hoymiles or Deye?

Yes. The connectors fitted comply with the MC4 standard, which is used worldwide in almost all solar panels and micro-inverters. They fit perfectly, both mechanically and electrically.

Can I shorten the cable?