Solar 30m extension cable 4 mm grade

Both sizes here are the same type of cable in two thicknesses, and the choice is nearly always about the length of the run, not the size of the array. On the rough rule of maximum of 10 amps per mm2 of copper, 4 mm2 carries about 40 amps and 6 mm2 about 60, and most small arrays never get near either.

What actually decides it is voltage drop. Every volt you lose in the cable is a volt that never reaches the battery, and unlike a one off inefficiency you pay that one every day for the life of the system. Put your length and current in and it will tell you which size to use.

Open the DC voltage drop calculator

No. Solar cable sits on a roof in full sun for twenty five years and ordinary PVC building cable does not survive that. It goes hard, then it cracks, then it tracks. Everything here is made to AS/NZS 5033:2014, the New Zealand solar standard in force since July 2015, and it is UV resistant, halogen free and rated -40°C to +90°C with a 25 year outdoor design life.

It is also rated 1000/1800V AC/DC, which matters more than people expect. A string of panels in series sits at a far higher voltage than the 12V or 24V you see on the other side of the charge controller.

Array leads have an MC4 on one end and bare wire on the other. That is the run from the panels to your charge controller: the MC4 clicks onto the array, the bare end goes into the controller terminals.

Extension leads have MC4 on both ends. They go into the middle of a run that already exists to make it longer, panel to panel or lead to array.

Solar cable is sold by the metre with nothing on either end, so you cut the length you want and terminate it yourself. It is the cheapest per metre and it is the only option when the run is an odd length.

Twin core puts the positive and the negative in one sheath, so it is one cable to run, one to clip and one hole to drill. Use it where both legs go the same way, which is most roof to controller runs.

Single core is two separate cables and you route them yourself. Use it when the two legs take different paths, or when there is a combiner or an isolator on the way. Both sizes come either way.

Almost certainly. MC4 has been the standard panel connector for years and it is what nearly everything sold here comes with. If your panels have something else on them, send us a photo of the connector before you order and we will tell you what you need.

4 mm2 is AWG 11 and 6 mm2 is AWG 9. The AWG number for this cable is on the spec table above.

The two systems do not line up exactly, so the nearest AWG size is always a little larger or smaller than the metric one.

See the full AWG to mm2 conversion chart

Yes, the array frame needs earthing, and you need earth cable plus something to earth it into.

The earth cable here is 4 mm2 to the same standard, sold by the metre. The rod is copper plated stainless steel, 2000 mm long and 14 mm across, and the brass clamp for landing the cable on it comes with it.

Length is the part people get caught by. You want at least 1800 mm of rod below the surface and about 150 mm left above ground to terminate onto, which is why the rod is 2000 mm. The shorter 1840 mm rods you will see around do not leave you enough once you allow for that.

As long as the voltage drop lets it be. Drop is proportional to length, so doubling the run doubles what you lose.

On a solar run that loss is permanent. It is not a one off, it is a slice off every kilowatt hour the array makes, every day, for twenty five years plus, so it is nearly always cheaper to go up a size than to accept it. We stock extension leads out to 30 m in both sizes. Past that the answer is usually a change to the array voltage rather than more copper, so talk to us before you buy.

Check the run with the DC voltage drop calculator

In the sun, yes, that is exactly what it is for. UV resistant, halogen free, and a 25 year outdoor design life.

Buried, put it in a conduit. The cable itself takes -40°C to +90°C, but a buried run meets spades, rodents and settling ground, and conduit is a great deal cheaper than digging it up again. Either way keep to the bend radius, which is five times the diameter of the cable.