Solar Switch

GaryS1953 wrote:
Hi All - When I installed my solar setup I put an in-line fuse between the panels and the charge controller, but unfortunately, it's on the roof. Never occurred to me I might want an easy way to shut off the amps to the charge controller. Now I'm realizing I will/do need to do maintenance on my battery bank, meaning I will need to disconnect them. Renogy says NOT to have solar power coming into the CC with no batteries connected, so I need a switch to turn them off and on. What do all of you use? I have 2 165 watt 12 volt panels in series connected to a Renogy Tracer 40 AMP MPPT CC. I have found plenty of switches to use on the battery side of the CC, and I have one there, but what is appropriate for the panel side?

Thanks!

Gary,

When you think about this it helps to think in terms of how does one protect the device or the conductors connected to it. Since the charge controller is fed from two sources, one of them current-limited, the other not, you are dealing with a couple of issues. First of all you need an isolating device (or disconnecting means, i.e."switch") on the PV input side of the charge controller to allow you to service the controller. Given that your installation won't deliver more than 30 amps from the solar array you could simply use a connector, such as an Anderson Powerpole or an MC4.

You also need to protect the wire from the battery to the charge controller, at or near the battery, with an appropriate overcurrent protective device. This device can also serve as the disconnecting means for the battery side of the charge controller if it's within 10 feet of the controller. This device needs to be rated for the for the available fault current from the battery and should be sized based on the lower of either the amperage rating of the controller or the ampacity of the wire going from the battery to the controller AND from the controller to the array (if ther's no internal overcurrent protection in the controller). This approach protects the wiring from a backfeed in case of a controller failure. The Bussman integrated switch/breaker units work well for this application. There are other ways to do this, with a fuse and separate switch for example, but the switch needs to be DC rated and of sufficient size (ampacity).