Solar panels installed without Circut Breakers

KD4UPL wrote:
Electricity doesn't know if it's in an inspected home installation or an RV. It will start a fire either way.
You need a fuse or circuit breaker between your charge controller and your battery. This will prevent fires if something in the charge controller ever shorts out.
You should also have all of your individual solar panels that are hooked in parallel fused (or breaker). I'm well aware that the vast majority of RV owners don't do this. It doesn't mean it's okay.
You need 4 fuses or breakers, one in series with each of your panels (assuming their all hooked in parallel). If your panels are in series and running to a high voltage MPPT controller that's a different story.
Any UL listed panel will have a sticker on the back that tells it's operating voltages and currents and also the maximum series fuse size.
Let's say all of your panels are rated for around 8 amps Isc. If one of them shorts out the other 3 will try to push their amperage thru the shorted panel. This would be 24 amps thru a panel designed for 8. As you can see, a fire may result. This is a code requirement for solar systems installed on buildings.

If you use an inline fuse between the controller and the battery, what size fuse? The system is 200W. Do you have a fuse on both positive and negative wires?

Thanks

You would normally only need to fuse positive battery wire. The fuse size would be determined by the wire size. #10 needs a 30 amp fuse for instance.
A 200 watt system, depending how it's configured, could deliver up to 17 amps into a battery. I would want at least a 20 amp fuse or larger. That would require a minimum of #12 wire.