Break Pos or Neg on Solar Panel wire to controller

[Ding Duck]

Definately need a fuse or something in the circuit.
The fuse would blow due to current from the battery, not neccessarily from the Panel.
If a Panel can produce say 10A at Isc (short circuit) and a short occurred downstream of this fuse, then a 10A fuse would never blow. That is, the Panel would not cause the fuse to blow, but the fault current coming back from the battery would. Assuming the fault is connected to the Neg of the Battery.

[rom]

Originally Posted by Ding Duck

Definately need a fuse or something in the circuit.
The fuse would blow due to current from the battery, not neccessarily from the Panel.
If a Panel can produce say 10A at Isc (short circuit) and a short occurred downstream of this fuse, then a 10A fuse would never blow. That is, the Panel would not cause the fuse to blow, but the fault current coming back from the battery would. Assuming the fault is connected to the Neg of the Battery.

I am having a hard trying to figure how this could happen... can you explain where such a fault would occur and would cause the battery to be directly connected to the panels ?

[Ding Duck]

Sorry rom, The Panel is connected to the battery as in the +ve of the panel goes straight to the battery. The -ve goes through the regulator. If the fuse was mounted up at the panel end and a + to - fault occurred, the fuse would not see the fault current, only the Isc of the panel. The fault would be seen by the battery for as long as the regulator was operating.
If you had a +ve to frame short ( not connected to -ve) then you would start to eventually see some 'Tea Stains' from the stainless caused by the leakage.
The best place is to mount any protective device down at the battery end.
Sorry, I may have been to clear. Here's a wiring diagram for a PL series regulator.

[rom]

Originally Posted by Ding Duck

Sorry rom, The Panel is connected to the battery as in the +ve of the panel goes straight to the battery. The -ve goes through the regulator. If the fuse was mounted up at the panel end and a + to - fault occurred, the fuse would not see the fault current, only the Isc of the panel. The fault would be seen by the battery for as long as the regulator was operating.
If you had a +ve to frame short ( not connected to -ve) then you would start to eventually see some 'Tea Stains' from the stainless caused by the leakage.
The best place is to mount any protective device down at the battery end.
Sorry, I may have been to clear. Here's a wiring diagram for a PL series regulator.

OK got it. I was assuming MPPT where you have +&- from the panels to the controller and other +&- cables from the controller to the battery.

[ramblinrod]

Originally Posted by rom

OK got it. I was assuming MPPT where you have +&- from the panels to the controller and other +&- cables from the controller to the battery.

What brand of solar controller is that?

[DeepFrz]

Its a Plasmatronics PL20. But that drawing sure doesn't look right to me.

Plasmatronics PL20 with LCD Display - 20 Amp - Regulators

[rom]

Originally Posted by ramblinrod

What brand of solar controller is that?

Mine is a victron mppt bluesolar 150/60, and Ding Duck seems to be using a PWM PL20 from plasmatronics.

[boatbod]

I am continually amazed at CF's ability to make any topic overly complex and then discuss it to death. :smh:

The OP asked which solar panel lead needed the switch, and the answer is the positive lead. Why? Because the less wire that is raised above ground potential, the less likelihood of a short occurring.

Electricity doesn't care which wire you interrupt as long as the circuit gets opened. A switch inserted anywhere in the circuit will do the necessary task, but why not add a safety factor and switch as close to the source of power (the panels) as possible.

[DotDun]

Originally Posted by boatbod

I am continually amazed at CF's ability to make any topic overly complex and then discuss it to death. :smh:

The OP asked which solar panel lead needed the switch, and the answer is the positive lead. Why? Because the less wire that is raised above ground potential, the less likelihood of a short occurring.

Electricity doesn't care which wire you interrupt as long as the circuit gets opened. A switch inserted anywhere in the circuit will do the necessary task, but why not add a safety factor and switch as close to the source of power (the panels) as possible.

The difference between a switch located inside or outside can be an issue.

[Hilbert]

Originally Posted by jbinbi

I would like to have my solar panels able to be turned off to the controller for any number of reasons. One main one is that my controller wants no V in when connecting/disconnecting to the battery. It is PITA to get to the little screws connecting the wires to the controller, so just wanting to do that means unconnecting the panels from the controller.

Having a switch/breaker would be much better. I purchase the blue seas breaker
https://www.bluesea.com/products/cat...ers/285-Series

Was planning on putting this on the POS wire from the panel to the controller. Then an electrical person at the yard said to break the NEG? I know about electron flow etc., but doesn't it make more sense to break the POS in this case.

From my controller's manual: "A clean connection to the battery (such as is provided by a disconnect or breaker) is required on power-up. Intermittent or noisy connections can cause the controller to initialize improperly"

I used a Blue Sea's battery switch for the battery disconnect (positive wire).

For a solar panel disconnect, I used an SPST toggle switch (positive wire). I was able to get away with this because my requirements were only for 33.2 VDC/ 7.3 amps, which was at the high end of the toggle switch rating. If it ever becomes a problem, I'll either replace it with another toggle or swap it out with something more robust.

Battery Panel:

[basssears]

Originally Posted by Safari38LH

Sorry for the thread drift, but does anyone have plugs on the deck to disconnect their panels or does everyone wire straight thru to the controller? I go straight through but see some advantage to being able to unplug right at the deck level. Is there such a thing as a MC4 deck plug?

I'll argue this is not thread drift (although I am a known drifter so ), as I am planning on using a plug through the deck to accomplish both easy removal of the panels when I'm away from the boat, and to accomplish what the OP is asking about which is making sure there is no juice from the panels to the controller when I don't want it. My controller very specifically states that I need to connect controller to battery before I connect controller to panels, so I need an easy way to break the panel connection.

Seems lots of through deck plugs are rather wimpy, so based on reading here and other recommendations I plan to use a trolling motor plug like this one from Minnkota:
https://www.amazon.com/MinnKota-MKR-.../dp/B001PTHKRQ

-- Bass

[john61ct]

I think better to just pass the wire through, put your proper MC4 join or switch at one end or the other.

Google the terms below, specs you need are the cable outside diameter, will be clamped watertight, so without slack. And thickness of deck/bulkhead/firewall.

A "split" version gland/connector means you don't need to pass through bare cable, OK to keep the MC4 on both ends.

Cable Glands / Cable Bushings / Cord Grip Connectors / Strain Relief

[ramblinrod]

Originally Posted by boatbod

I am continually amazed at CF's ability to make any topic overly complex and then discuss it to death. :smh:

The OP asked which solar panel lead needed the switch, and the answer is the positive lead. Why? Because the less wire that is raised above ground potential, the less likelihood of a short occurring.

Electricity doesn't care which wire you interrupt as long as the circuit gets opened. A switch inserted anywhere in the circuit will do the necessary task, but why not add a safety factor and switch as close to the source of power (the panels) as possible.

I am continually amazed at the posting of something already posted (post # 37) and then complaining about the number of posts. ;-)

[ramblinrod]

Originally Posted by DeepFrz

Its a Plasmatronics PL20. But that drawing sure doesn't look right to me.

Plasmatronics PL20 with LCD Display - 20 Amp - Regulators

$335 for a 20 A PWM charge controller????

Yikes!!!!

Is it gold plated?????

PS, this is the most unusual wiring requirement for a solar charge controller I have ever seen. Most are like the PL60.

[CaptBob84]

I recommend using a Midnite Solar PV-3 or their "Baby Box" DIN rail breaker box. It is a common item used on land based solar arrays

https://www.emarineinc.com/MidNite_S...ll_Breaker_Box

Capt. Bob