Fuse Between Solar Panel And Controller

In a parallel system a combiner box is used that holds the fuses breakers to each panel plus one or more combined fuse leading to the charge controller or grid tie inverter see figure.

Fuse between solar panel and controller.

The second fuse between your solar panels and charge controller is a little bit different to figure out. The first version of this system used 20a class cc fuses and a bulky fuse box meant for home solar. That does not mean you should use a 80 amp ocpd it just means that is the largest you can use in your application. These are off grid so we ll have 55w solar panels charging 12v 100ah deep cycle batteries during the day and the sensor gnomes use that battery power to listen for bats at night.

When sizing this combined fuse breaker we must first determine the worst case current that will flow based on our specific panels. With an 8 awg copper conductor between the controller and battery you can use a fuse or breaker up to 80 amps using a 90 degree conductor insulation in free air. For that setup you will not need fuses between the solar panels and the charge controller. If the panels are connected in series the voltage of each panel is added but the amperage stays the same.