PV isolation-switch or breaker

DIY
1

I have a OEM solar system installed in a motorhome. I have a PWM solar controller charger(SCC) which has a fuse between the PV and the SCC and a breaker between the SCC and the battery. I’m upgrading to Smartcharger MPPT 100/50. There is no DC isolation switch between the PV and the SCC. My PV array short circuit specs is way below the 100V and 50A limits for the SCC.

I want to eliminate the fuse between the PV and the SCC as it is only accessible by unscrewing an access panel. I want to replace the fuse with a double pole DC breaker close to a rating of 60A/125VDC. I was thinking this would provide circuit protection and PV DC solution in a single solution which be mounted on an easily accessible panel.

There is debate whether both legs of the solar panels need to be switched for DC isolation to the SCC. Do both legs need to be switched?

The other solution is using a double pole switch and use a single pole breaker in the positive leg of the PV and/or keep the fuse between the SCC and the PV.

So the main question is can I replace the fuse between the SCC and the PV with a DC double pole breaker for SCC protection plus have an PV isolation switch.

2

Problem with fuses in pv Installations is that the working current and short-circuit current are too close to each other. So you can just as well forget the fuse, it’ll never blow.

3

Not sure of that as some motorhomes owners had their fuses been blown. Most owners don’t know there is a fuse between the SCC and the PV as the fuse in a hidden space, which leads some head scratching as try to figure why the power to the SCC has gone to zero when the fuse has blown.