How to Wire a Solar Junction Box

Solar Junction Box 1
Solar Junction Box 2
Solar Junction Box 3
Solar Junction Box 1
Solar Junction Box 2
Solar Junction Box 3

How to wire a solar panel junction box (or terminal box) is one of the most commonly asked question that we receive. This is a short introduction on how to wire a solar junction box.

Some of the solar panels, such as Kyocera & Sharp come with serviceable junction boxes. However, most solar panels require wiring the junction box before installation.

  1. To begin, unscrew the 4 screws in order to open the junction box. Inside, you will notice that there are more screws than you might expect. There are only two screws that you will need to unscrew. These are the ones on the bottom left and right, under which there should be a positive and negative sign.
     
  2. Don't disconnect the mounting and diode connection screws.
     
  3. Bring the wires into the junction box via a conduit or directly with a cable using a rainproof cable connector.

Here are some websites for further detail photographs and explanation.

[image credit: robpatton]

Comments

What size wire do you recommend when wiring solar panels with a junction box on my boat?   Does the wire size change for different applications?   Is the wire special PV wire, meaning does it need to be rated for UV?   Thanks for the help on this.   I found this article to be  very help to see what I am going to receive when my panels arrive.

Jon,

I'd like to refer you this article about the wire sizes for different lengths. The more distance you have, the thicker wire you need to use (in order to avoid voltage drop).

You are right about UV effect. A cable that is constantly under sun, you'll need to a UV rated wire. AWG #10 USE-2 wires are commonly used for most of the ongrid, offgrid applications.