Looking for help finding some sort of cut off switch that I can mount on the wall inside my coach next to where the charge controller is currently mounted. Side note: I'm pretty much hemmed into putting the cut off switch next to the charge controller due to the way the previous owner wired the array into the coach. Trying to find anything that isn't big &/or big & ugly has proven to be an exercise in futility. Thanks in advance!

Are you wanting to shut off power from the solar panels to the controller? If yes, why? If your batteries are full and your solar controller is a good one and is working correctly, it will never put more power into the batteries than what they need. That's what the controller is for.

If needing to disconnect panels from system it's as easy as pushing a button.

Itinerant1 wrote:If needing to disconnect panels from system it's as easy as pushing a button.Actually, you should have two DC breakers like that, one between the solar panels and the controller, and one after the controller, before the inverter, so that you can completely isolate the controller from the system if need be. It looks like that's how this system is wired, and that's how I wired my system.

Recs for Solar Cut Off Switch? | Good Sam Community

RLS7201
Explorer II
Dec 17, 2019
pianotuna wrote:
Hi,

On AC power the direction of the voltage changes 30 times a second. On DC it is one way, so an arc requires a larger gap.

Here is a high voltage example:

https://www.youtube.com/watch?v=d3U1yrBI3xc

That is what is happening inside the switch. The arcing causes pitting of the contacts.

RLS7201 wrote:
pianotuna wrote:
BFL13,

With respect, using a switch rated for AC in a DC circuit may lead to arcing.

Don, what are the design characteristics of AC and DC switches that differentiates the two? What inhibits the arching in one design and not the other. Inquiring minds want to know.

Richard

I would suggest that 60 cycle AC service changed direction 120 time a second NOT 30.

Richard
Powertour
Explorer II
Dec 12, 2019
Thanks for all the info & the ideas. i ended up going with this little switch purchase off Amazon.

https://imgur.com/a/qi0CCw2

As seen Installed next to my inverter controller.

https://imgur.com/a/PDYSFJn
BFL13
Explorer II
Dec 12, 2019
TechWriter wrote:
BFL13 wrote:

Ok, so which is the higher potential????

Follow the PV array-to-Controller circuit and the Controller-to-Batteries circuit through the 4 breakers.

Thanks! OK, so the MNEPV-15s have their double pos such that the panels are higher than the controller, and the controller is higher than the batteries.

This would support the panels as a current source to charge the batteries, with the panels having a higher voltage than the batteries.

I don't understand the arrows on the controller drawing, where pos and neg are pointing the same way. What are the circuits here?

EDIT--the battery cell while being charged, has electrons flowing through an external circuit to the battery's negative plate from the positive plate. (Reversed for when being discharged)

So you put the pos to pos and the neg to neg with the charger (panel)and battery, and you have the charger being discharged (neg to pos) and the battery being charged (pos to neg)
TechWriter
Explorer
Dec 12, 2019
BFL13 wrote:

Ok, so which is the higher potential????

Follow the PV array-to-Controller circuit and the Controller-to-Batteries circuit through the 4 breakers.
pianotuna
Nomad III
Dec 12, 2019
Hi BFL13,

The higher potential is a dead short across the battery bank.
BFL13
Explorer II
Dec 12, 2019
Here is something about being 80v or over on the solar and no auto-reset breakers allowed,

https://www.technicalsafetybc.ca/sites/default/files/csa-fia36443694-polarityidpvdc.pdf
BFL13
Explorer II
Dec 12, 2019
TechWriter wrote:
BFL13 wrote:

On polarity "direction" I don't see the way that is marked on a switch, so how to get it right way around if on the battery neg wire or pos wire?

The higher potential terminal on this DC breaker is marked with a ++ on this switch:

Ok, so which is the higher potential????

I remember around 1981, some of our electronic techs took a course in the States on a particular equipment. After, they said it was a good course, except they had to get used to "how they taught diodes". (Backwards)

Off topic, but anyway, one of them was French from Quebec, and he said the trouble was the instructor kept calling everything (like a diode) a "critter". After some of that he had to ask, "Please, Sir, what's a "critter?" :)
TechWriter
Explorer
Dec 11, 2019
BFL13 wrote:

On polarity "direction" I don't see the way that is marked on a switch, so how to get it right way around if on the battery neg wire or pos wire?

The higher potential terminal on this DC breaker is marked with a ++ on this switch:
BFL13
Explorer II
Dec 11, 2019
The ads don't mention bi-directional (at least not at this store)

Here is one that is "negative" polarity and it says to mount it on the battery's negative post. Does that change the idea of what "polarity" means?

https://www.princessauto.com/en/detail/300a-rotary-dial-battery-disconnect-switch/A-p8618415e
pianotuna
Nomad III
Dec 11, 2019
BFL13,

I'd use a bi directional switch with arc protection both ways.

BFL13 wrote:
On polarity "direction" I don't see the way that is marked on a switch, so how to get it right way around if on the battery neg wire or pos wire? Would want an arrow toward the battery (or solar panel) positive post in the States (or negative post in Canada?)

With the solar controller in the middle and the array as the "current source", which way is "positive"? You have the battery circuit direction and the array circuit direction, but the PWM controller passes the battery voltage to the array. How can it do that if they are in opposite directions?