Adding a portable solar panel to prewired outlet

[Seymour2Lane]

I have a 2016 View with the Zamp prewired solar controller, 1- 100w panel on the roof and a connection for a portable panel in the electrical bay. When I checked that plug for polarity (before plugging in my 120w panel) I found it had 18.2v at the plug? When I unplugged the roof panel the plug for the portable panel still had 13.8v. I figured that the 18.2v is the 'unregulated' voltage from the roof panel and the 13.8v is from the house battery. I should have checked the other two ports on the roof for voltage but didn't.
Is this normal? OK to plug my panel in with this setup? Seems like the killiwiggles might not get along pushing both ways down the wires? Just don't want to fry something.
Thanks in advance, Mike

[John Hilley]

It appears that that port places the panel in parallel to the roof panel. That is what you want. It appears that you may not have a solar controller and that the panel is connected directly to the batteries. If you have verified the existence of a Zamp controller, battery voltage may be what you see at the PV input.

It would be best to have at least a 20 amp PWM controller to regulate the charge to the batteries.

[Seymour2Lane]

John,
The roof solar panel does run through the stock Zamp 30 amp PWM controller. I just figured there should be a diode or something to block the roof panel voltage from 'back feeding' to the portable panel plug. I get that panels in parallel is a good thing.
BTW, I did remove the cheapo PWM controller that came prewired to my portable panel so there wouldn't be two controllers involved.
Regards, Mike