Solar Connectors

MC4 connectors, branch connectors, inline PV fuses, DC isolator switches and the spanner that puts them together.

MC4 is the standard fitting for solar. Mated, the pair seals, which is what lets a connection sit out on a roof for the life of the array. Ours are Slocable, rated 32A at 1000V DC, and they take either 4 mm2 or 6 mm2 cable. They are the solid copper bar type, so you can solder or crimp them. The winged crimp only type is cheaper and it does not last anything like as long in the field.

Connectors come as a pair, one male and one female, singly or in packs of 2, 4 and 12. A length of solar cable needs a pair at each end, so count the joins before you order rather than the cables.

Branch connectors put panels, or whole strings of panels, in parallel. The T range is named for how many go into the one output, so a 3T takes three. The Y range is named by the number of branches on the connector itself, because a Y is not fixed to running one way and can just as easily split one line out into several. Each one comes as a matched pair, one male to several female and one female to several male, so a single set does both legs of the array. They are 30A at 1000V DC with IP67 housings.

A fuse on every string of PV panels is now required. The inline fuses go on the positive wire of each string. They are 10A, 20A and 30A, all 1000V DC and TUV Rheinland certified, and they snap into the MC4 line in about five seconds, so you can fuse an array without a combiner box anywhere on the roof. Changing one later is a minute’s work at the panel.

The DC isolator switches go between the array and the charge controller, so you can kill the array before anyone works on anything downstream. Both are 32A at 1000V, IP66 and lockable, certified to AS/NZS 3947.3:2001 and IEC 60947-3 by TUV Rheinland. The two pole has MC4 tails already fitted and plugs straight in. The four pole switches both legs of two separate arrays.

The MC4 spanner is the last piece. The connectors lock by design, and the spanner is what gets one apart again without wrecking it.