Solar Switch

[GaryS1953]

Hi All - When I installed my solar setup I put an in-line fuse between the panels and the charge controller, but unfortunately, it's on the roof. Never occurred to me I might want an easy way to shut off the amps to the charge controller. Now I'm realizing I will/do need to do maintenance on my battery bank, meaning I will need to disconnect them. Renogy says NOT to have solar power coming into the CC with no batteries connected, so I need a switch to turn them off and on. What do all of you use? I have 2 165 watt 12 volt panels in series connected to a Renogy Tracer 40 AMP MPPT CC. I have found plenty of switches to use on the battery side of the CC, and I have one there, but what is appropriate for the panel side?

Thanks!

[baphenatem]

GaryS1953 wrote:
So what about something like this this ? It has the advantage of fitting in the small space I have and can be screwed right into the wall below the controller.

It would probably work for disconnecting purposes, but given the price, source, and quality, I'm not sure that I'd trust it's actual overcurrent capabilities. However, I've been surprised before.

By the way, others on this forum might want to take the time to check out Section 90.2(A) of the Natiinal Electrical Code as to it's applicability to RV's. Yes, it's difficult to adhere to all of it's provisions when installing PV on an RV, but the overall provisions for safety and good design are valid nonetheless. While no firefighters will be going on the RV roof, it's avoiding the need for them to show up in the first place that is the overall goal.

[jake2250]

Thanks Gary,, I called my Solar Guru,, if you lived near we would have a drink!! THANKS!!

[GaryS1953]

Happy Birthday !!

[jake2250]

Well,, just got a great bottle of 33 year old Scotch for my Birthday, My solar buddy came over and we had a great discussion about this thread! Well, it turns out,, Heavy Duty is GOOD! But in reality, I will buy a 110V/30 amp single pole switch and cut power to the HOT side of my meager 200 watt 12V panels.
He explains that I will not loose anything thru the switch, where as that Small little guy switch will loose some! We did shoot around dual pole or single pole,, He asks "Where is the switch"? I say between panels and CC. He tells me my Charge Controller already has fuses inbound and outbound. Tells me to pull a fuse,, But I want simplicity.. Given my situation an regular Home 110v rocker switch will work. But then he went on about some really complex (home or commercial)installations that require extreme shut off switching and phasing!
So when I ask for parameters,, He tells me it all comes down to the wallet,, What and how warm do I want to feel?? What is the minimum and what is the Maximum? He says Minimum,Double amps, and 2/3 Voltage and you will be good.. But if you had an yard of money,, Go Big with handles, flags and blinking lights!! I poured another drink and we moved onto Trailer tire brands!!

[GaryS1953]

So what about something like this this ? It has the advantage of fitting in the small space I have and can be screwed right into the wall below the controller.

[BFL13]

With all respect to qualified stick house solar installers, my understanding is that an RV is not a stick house, and so "The Code" does not apply, and so the panels need not be "grounded" (to what in an RV? ) We don't have to worry about firemen on the roof trying to put out a chimney fire and stepping on live panel wires under water and all that.

Some controllers are internal pos ground and some are neg ground if you ever "chassis grounded" the controller (Why do that in an RV?.) Some have a plastic casing, so that would be a good trick with them.

So, AFAIK the only reason to have the panel to controller switch is for those controllers which will fry if left on panel with no battery/ (There is incomplete info on which ones they are, so the safe thing is to assume yours will fry.)

So bottom line is, with panels and controller not "grounded" in the RV, it makes no difference which wire you switch to "open."

If you chose to switch the neg wire and somehow the pos got shorted to the neg wire (how? ), so what? Panels don't mind being shorted.

[baphenatem]

GaryS1953 wrote:
Tom - I mis-spoke. I DO have a removable 40 AMP fuse between the CC ant the batteries. The Battery switch is acrually between the batteries and the campers 12volt system, so the CC IS protected from battery currentl, I think. I think I just need to decide how to easily isolate the CC from the panels.

Gary,

Is the 40A fuse socketed, or is it in a holder or bolted in? Technically, the Code allows an isolation device, such as a removeable fuse if the circuit current is less than 30A. Above 30A a disconnect is required. The simple and cheap solution for a switch would be to find a surplus 40A (or higher, since you have a fuse) DC rated breaker on eBay. Amazon also has some inexpensive battery switches that would do the job.

[time2roll]

When I was looking at switches Eaton tech recommended DH221NGK rated to switch 250 volts DC and 30 amps. I have about 100 volts 8 amps.
try Google shopping "DH221NGK" for best price. It is a bit bulky and only rated NEMA 1 for indoors.

I am actually using DP221NGB but it is not rated for DC current. It does arc a bit during disconnect but seems to extinguish the spark OK and it is in a metal box. I think it helps to cut both sides together which actually doubles the gap the power must jump.

OP is only about 30 vdc so not such a big deal.
You Tube video on switching 220 vac vs 220 vdc

[CA_Traveler]

pianotuna wrote:
Hi CA Traveler,

With respect, you may do as you wish with your own RV, but to recommend using an AC switch for a DC circuit is perhaps unwise.

For those of you who wish to find out why, follow this link:

https://www.youtube.com/watch?v=z0QhkuGClMw

CA Traveler wrote:
Yes I know the A/C switch is not DC rated but for my use and application I would expect it to last a very long time.

Good that you emphasized that DC causes more arcing. Prior to my post AC vs DC had not been mentioned.

But with a 8A DC load I'm not concerned about using a 60A rated steel enclosed A/C disconnect switch.

[pianotuna]

Hi CA Traveler,

With respect, you may do as you wish with your own RV, but to recommend using an AC switch for a DC circuit is perhaps unwise.

For those of you who wish to find out why, follow this link:

https://www.youtube.com/watch?v=z0QhkuGClMw

CA Traveler wrote:
Yes I know the A/C switch is not DC rated but for my use and application I would expect it to last a very long time.

[GaryS1953]

Tom - I mis-spoke. I DO have a removable 40 AMP fuse between the CC ant the batteries. The Battery switch is acrually between the batteries and the campers 12volt system, so the CC IS protected from battery currentl, I think. I think I just need to decide how to easily isolate the CC from the panels.

[baphenatem]

GaryS1953 wrote:
Ok, you guys have given me a lot of great ideas, and I appreciate it. One more question, whatever switch I use, should it be on the negative line or the positive line, or does it matter?

On the positive (ungrounded) side.

[CA_Traveler]

GaryS1953 wrote:
Ok, you guys have given me a lot of great ideas, and I appreciate it. One more question, whatever switch I use, should it be on the negative line or the positive line, or does it matter?

Doesn't matter but since positive is usually switched that would be my choice for a single switch.

[baphenatem]

GaryS1953 wrote:
Hi All - When I installed my solar setup I put an in-line fuse between the panels and the charge controller, but unfortunately, it's on the roof. Never occurred to me I might want an easy way to shut off the amps to the charge controller. Now I'm realizing I will/do need to do maintenance on my battery bank, meaning I will need to disconnect them. Renogy says NOT to have solar power coming into the CC with no batteries connected, so I need a switch to turn them off and on. What do all of you use? I have 2 165 watt 12 volt panels in series connected to a Renogy Tracer 40 AMP MPPT CC. I have found plenty of switches to use on the battery side of the CC, and I have one there, but what is appropriate for the panel side?

Thanks!

Gary,

When you think about this it helps to think in terms of how does one protect the device or the conductors connected to it. Since the charge controller is fed from two sources, one of them current-limited, the other not, you are dealing with a couple of issues. First of all you need an isolating device (or disconnecting means, i.e."switch") on the PV input side of the charge controller to allow you to service the controller. Given that your installation won't deliver more than 30 amps from the solar array you could simply use a connector, such as an Anderson Powerpole or an MC4.

You also need to protect the wire from the battery to the charge controller, at or near the battery, with an appropriate overcurrent protective device. This device can also serve as the disconnecting means for the battery side of the charge controller if it's within 10 feet of the controller. This device needs to be rated for the for the available fault current from the battery and should be sized based on the lower of either the amperage rating of the controller or the ampacity of the wire going from the battery to the controller AND from the controller to the array (if ther's no internal overcurrent protection in the controller). This approach protects the wiring from a backfeed in case of a controller failure. The Bussman integrated switch/breaker units work well for this application. There are other ways to do this, with a fuse and separate switch for example, but the switch needs to be DC rated and of sufficient size (ampacity).