Battery cut-off switch and Solar ?

And just the opposite during installation. With an MC4 disconnected I wired the panel wires to the switch and controller. Checked, double checked and triple checked the wiring for polarity. With the panel and battery switches off connect the MC4 connector. Now with a voltmeter recheck the polarity to the switch. Then battery switch on then the panel switch on. Success! :B

So, back to Mr Wiz's switches for higher DC voltages. Main thing is to have them handy so you don't have to go on the roof.

BFL13 wrote:

phemens wrote:
The controllers have set screws for the wiring, but I’d rather not have bare wires dangling around if I can avoid it, rather save fireworks for holidays ;).
The DC breakers sound interesting, I will look into those.

You can cover the bare wire end with a wire nut during the time it is out of its slot. To disconnect the array you can use either the pos or neg "array" wire.

Definitely not advised as one panel has 30V and the other 90V.

If I had to do anything with my panel wiring (90V+) I would first turn off the panel switch then the battery switch and then disconnect one of the MC4 connectors on the roof. Then I could safely be a wire jockey.

I used a 240V AC disconnect panel which is about $8 from HD. It's 2 pole so you could connect/disconnect both panels together or use 1 for each panel. There is no need for a fuse or CB for your panels. My panels are 90V+ at 8A+.

While not DC rated there is no need for concern with this 60A AC rated panel and a few panel amps.

phemens wrote:
The controllers have set screws for the wiring, but I’d rather not have bare wires dangling around if I can avoid it, rather save fireworks for holidays ;).
The DC breakers sound interesting, I will look into those.

You can cover the bare wire end with a wire nut during the time it is out of its slot. To disconnect the array you can use either the pos or neg "array" wire.

My question is, I assume that I would need to cut off the positive feeds from the solar panels to the MPPT controllers before switching off access to the batteries?

you can use any switches rated for the amps and volts

i went with marine style circuit breaker
push the RED button and it disconnects, push or slide lever for reset(depends on the brand)
various brands and voltages available

https://www.amazon.com/Bussmann-CB185-40-Surface-Mount-Circuit-Breakers/dp/B01BDNVVSM/ref=pd_lpo_vtph_60_tr_t_2?_encoding=UTF8&psc=1&refRID=RQ3RA4SSH4AW07R4C6VC

The controllers have set screws for the wiring, but I’d rather not have bare wires dangling around if I can avoid it, rather save fireworks for holidays ;).
The DC breakers sound interesting, I will look into those.

phemens wrote:
I have a battery cut-off switch installed between battery bank positive distribution post (all batteries cabled to posts with equal length cables) and the main distribution block (where I have the feeds from 2 solar controllers, house main, inverter). My question is, I assume that I would need to cut off the positive feeds from the solar panels to the MPPT controllers before switching off access to the batteries?
If so, can I install same type of cut-off switches to each controller - one is wired at ~ 30 volts from a single 250w panel, the other gets ~ 90 volts from 2 x 325 panels wired in series.

Yes, where it is handy to get at, one for each controller. Can be on either neg or pos. Anything that will disconnect panel from controller. A switch, or a fuse that can be pulled. Wirenut for a portable set.

Some controllers have set-screw slots for the wires, which makes it easy to just take a wire out from the array side, but others have screws for ring terminals. These are awkward, so for them you would want to insert a switch or fuse in the wire.

It would be best to have disconnects on the PV circuits feeding the charge controllers. While in theory your battery disconnect type switch should work just fine I don't know if it's actually rated for that high of voltage. DC circuit breakers, rated at 125v DC are readily available as they are typically used in home type solar systems just for this purpose. Outback and MidNite solar both sell the breakers under their branding but I think they are both made by AirPax or some other third party.
Square D QO brand circuit breakers are rated for up to 50 volts DC so one of those breakers would work on your lower voltage PV circuit but not the higher voltage one.

landyacht318 wrote:
Most Solar controllers I have seen the instructions on, say to disconnect the panels from controller before disconnecting controller from battery.

I've screwed up a few times and not followed through on this, and it still works, but I assume it is cumulatively damaging to the magic smoke still contained inside the controller.

HeHe :)

X2 I now have a way to disconnect the solar and the battery from the controller. :B

Housted