Question about plugging in a Portable Panel through existing MPPT

[ChrisPuth]

Hello all,

I am planning on installing two 120watt "24 volt" panels in parallel on my roof top. These panels are from NewPowa and are 120W 40.5Voc and 3.7Isc each.

I have a third identical panel that I would like to use as a portable panel occasionally. And when it is deployed, all 3 panels will be in parallel and all feeding into my MPPT charge controller. I want to be sure folks understand this is just a panel and not a solar suitcase with its own built-in controller.

My concern is with plugging in the portable panel. Even if the Circuit Breaker is open, so that the roof top panels are disconnected from the charge controller, there will still be ~40 volts on that connector junction. Will this arc when the portable panel is plugged in? Am I going to char up the connectors over time? Is there a better way to do this?

Thanks,

 

[chrisski]

I use Anderson power pole connectors set up 66 volts 6 amps. These have not arced when I plug and unplug them.

With those both ends get disconnected. I’ve seen panels arc at 48 volts when doing a short circuit amps test.

 

[HRTKD]

I have four 320 watt panels. Two on the roof and two on the ground. I chose to use two different solar charge controllers for each set.

Your panels are a little small. You may find later that an upgrade to larger panels is in order, at least for the ground deployment. If you have separate controllers, it's an easy upgrade as different sized/voltage/amperage panels won't matter. With the separate controllers you can skip the use of the inline fuses and wire the rooftop panels in series.

The circuit coming in from the exterior wall of the trailer has a dedicated circuit breaker before its solar charge controller. That allows me to isolate that circuit. It may be paranoia on my part, but should someone maliciously try to fry my system by connecting to the PV port, nothing would happen.