Installing breakers on + and - from roof solar and Zamp

[Chama]

Presently in our 2019 E-21 (as Escape wired it) we have a + and - wire coming from roof solar and a + an - wire coming from Zamp. The 2 + wires are wire-nutted together and the - wires are wired nutted together then a pigtail from each wire nut goes to the PWM 30 charge controller. The problem with this is that the Zamp port is always hot when the roof solar is getting sun. I would like to install 15 amp DC breakers on the roof panel wires and on the Zamp panel wires to have a way to shut off the two panels and to protect the charge controller and to make the Zamp port not hot when the roof panel is getting sun.

My question is: in installing breakers on the incoming solar cables, should we install a 15 amp DC breaker on each incoming solar cable then wire nut (or somehow otherwise combine) the output together to the charge controller OR combine the two solar lines somehow before the breaker then run the pigtail into a single DC breaker with output to the new Victron CC? Which is the correct way to do this?

[hugh]

Originally Posted by Chama

Presently in our 2019 E-21 (as Escape wired it) we have a + and - wire coming from roof solar and a + an - wire coming from Zamp. The 2 + wires are wire-nutted together and the - wires are wired nutted together then a pigtail from each wire nut goes to the PWM 30 charge controller. The problem with this is that the Zamp port is always hot when the roof solar is getting sun. I would like to install 15 amp DC breakers on the roof panel wires and on the Zamp panel wires to have a way to shut off the two panels and to protect the charge controller and to make the Zamp port not hot when the roof panel is getting sun.

My question is: in installing breakers on the incoming solar cables, should we install a 15 amp DC breaker on each incoming solar cable then wire nut (or somehow otherwise combine) the output together to the charge controller OR combine the two solar lines somehow before the breaker then run the pigtail into a single DC breaker with output to the new Victron CC? Which is the correct way to do this?

What's the concern with the current wiring configuration? Are you worried about a short causing overheating and a fire?

I'm asking because a solar panel isn't like a battery. A single panel probably can't push more than 10 amps or so, even on a dead short, so unless the wire is extremely undersized, there's no risk of overheating the wire even with a short.

[Viajante]

There have been discussions about possible damage to the solar controller if it is disconnected from the battery while still receiving current from the solar panel.

Owners have added an inline fuse to the +cable between the panel and the controller to act as a switch so that it can be pulled to interrupt the circuit. Others have added an on-off switch to the +cable in a convenient location for disconnecting the panel from the controller.

This is useful in situations like removing the batteries for storage.

[Perry Butler]

Originally Posted by Viajante

There have been discussions about possible damage to the solar controller if it is disconnected from the battery while still receiving current from the solar panel.

Owners have added an inline fuse to the +cable between the panel and the controller to act as a switch so that it can be pulled to interrupt the circuit. Others have added an on-off switch to the +cable in a convenient location for disconnecting the panel from the controller.

This is useful in situations like removing the batteries for storage.

If you have a Victron solar controller you can turn off the roof solar. However, I will add a breaker to the roof side when I remove our 160 watt panel to install two 200 watt 24v panels in series for additional safety. I have a 30amp breaker installed between the controller and the batteries to disconnect the battery side.

Food for thought,

Perry

[Chama]

Hugh, my concern about needing breakers on the solar panels incoming cables is for two reasons: we need a way to shut off incoming solar panel power and we need a way to shut off power that backflows to the Zamp port connector (connected in parallel with roof solar) when the roof panel is producing power but no panel is attached to the Zamp port, like when going down the road or at a FHU campsite. It may also help protect the charge controller in the event of a short from either the roof panel or from the Zamp port or, as other posters have mentioned, when removing the battery.

[Rossue]

Originally Posted by Perry Butler

If you have a Victron solar controller you can turn off the roof solar. However, I will add a breaker to the roof side when I remove our 160 watt panel to install two 200 watt 24v panels in series for additional safety. I have a 30amp breaker installed between the controller and the batteries to disconnect the battery side.

Food for thought,

Perry

Am sure you are a LOT more savvy re: electrical than I am, however wanted to share an experience with having my two 195 12V panels for my van wired in series. The two EcoWorthy panels are 23V open circuit voltage output each. Wired in series they combine to generate 2X that or 46V. My Goal Zero 3000X is rated for 50V Max and this setup worked great until a firmware update was done. After that no solar charging until the wiring was changed to parallel. This then made the total output 23V and the panels once again charge it up.

Am seeing a 200W 24V Newpowa on Amazon and the open circuit voltage is 43.6V- so wiring in series would double that to 87.2V. Is this correct, and if so would a 30 amp breaker be sufficient?

Which brings up the pros & cons of parallel vs. series for this application.

[Perry Butler]

Originally Posted by Rossue

Am sure you are a LOT more savvy re: electrical than I am, however wanted to share an experience with having my two 195 12V panels for my van wired in series. The two EcoWorthy panels are 23V open circuit voltage output each. Wired in series they combine to generate 2X that or 46V. My Goal Zero 3000X is rated for 50V Max and this setup worked great until a firmware update was done. After that no solar charging until the wiring was changed to parallel. This then made the total output 23V and the panels once again charge it up.

Am seeing a 200W 24V Newpowa on Amazon and the open circuit voltage is 43.6V- so wiring in series would double that to 87.2V. Is this correct, and if so would a 30 amp breaker be sufficient?

Which brings up the pros & cons of parallel vs. series for this application.

Use the VMP at 37.2, not the open circuit at 43.6, to give a voltage to the solar controller of 74.4. The amps in series stay the same. Basically when you double the voltage you half the amps, so still 5.38. A 10 amp breaker should be sufficient at 74.4 volts.

In parallel the amps would be double or 10.76, too much for a 10 amp breaker.

Mowgli Adventures Series vs Parallel gives a great explaination and includes easy to use calculators.

In this case, I'm dyslexic, so always check my results. I do, but sometimes I fail. I was given bad advice from AM Solar who recommended a 100/50 controller ($323) for three Rich Solar 24v panels. Three 24v panels with a VMP of 37.6 will give a voltage of 113 volts, too big for the expensive 110/50 I ended up buying last January (and too late to return).

A 150/70 Victron controller is $638. If I add a third panel I'll run another set of wires down the fridge vent and buy a 100/30 controller at $226 instead. This will be a very expensive lesson.

Hope this helps,

Perry