The video uploader shows how we can either make or buy a DIN rail box “passthrough” device that will give us the ability to take advantage of the disconnect breaker and surge protection devices (SPD) that are commonly found in solar combiner boxes. Since we don’t need to combine strings to reduce the voltage, we just want to run our strings through this box for added safety and convenience. We still need a fuse somewhere in the line and this box does not contain one, but have no fear! We can just use one of these inline fuses from Rich Solar and pop it on the positive wire where our string begins at the first panel. We use a fuse with an amp rating about 5 amps above the max output current of our panels. We don’t want to go too high though, the fuse should blow before any current could go over the max input current rating of our charge controller. Posted by Ben Campbell