Double Pole Breaker

[epearce]

After having a nagging suspicion that a single-pole breaker/disconnect on the + side of my solar panels was probably not best practice for the floating high-voltage solar panels on my 200MK, I looked around and could not find much guidance on RV solar panel breakers that address the single-pole vs. double-pole question. The solar panel discussions were pretty clear that best practice was to use a solar specific double-pole DC breaker.

Anyone have any wisdom or experience on this topic?

[ncitro]

After having a nagging suspicion that a single-pole breaker/disconnect on the + side of my solar panels was probably not best practice for the floating high-voltage solar panels on my 200MK, I looked around and could not find much guidance on RV solar panel breakers that address the single-pole vs. double-pole question. The solar panel discussions were pretty clear that best practice was to use a solar specific double-pole DC breaker.

Anyone have any wisdom or experience on this topic?

I feel like howson went down this rabbit hole. My understanding is it's recommended (maybe even required) for residential installs, but is not a requirement for RV. Howard will be along shortly but I think he had a conversation with the folks at AMSolar about it.

[TedS]

I'm sure being solar specific doesn't matter as long as it's DC rated.

[TucsonJim]

It's important to note that a standard household breaker that is rated for 120V AC will not supply the same protection in a direct current circuit. For example, look at the specifications for the breaker in the link below:

https://www.se.com/us/en/product/QO1...plug-in-mount/

The voltage rating is for 120/240 V Alternating Current. But it is only rated for 48 Volts of Direct Current.

Any breaker selected for a solar circuit should be based on it's DC voltage rating.

Jim

[howson]

epearce -- ncitro remembers correctly (it depends on the voltage level). The thread where this is discussed at length is here: https://gdrvowners.com/forum/solar/9...connect-switch

A related discussion on shutoff switches and voltage levels is in one of Keith's ( Yoda ) threads here: https://gdrvowners.com/forum/solar/4...rge-controller

Howard

[Scott'n'Wendy]

I'm sure being solar specific doesn't matter as long as it's DC rated.

^^^ This ^^^

Most people figure a breaker good for 120 volts is 120vac or vdc. They are not. Both AC and DC are forms of electricity but very different animals in how they behave regarding the opening of a circuit in particular.

[epearce]

epearce -- ncitro remembers correctly (it depends on the voltage level). The thread where this is discussed at length is here: https://gdrvowners.com/forum/solar/9...connect-switch

A related discussion on shutoff switches and voltage levels is in one of Keith's ( Yoda ) threads here: https://gdrvowners.com/forum/solar/4...rge-controller

Howard

That was a useful thread... and pretty much what I expected...

• I think most of us know that AC and DC breakers (and switches for that matter) are different, because of arcing concerns.
• Solar panel (PV) voltages can be very high, especially if they are wired in series, as they usually are in an RV, and can exceed voltages of battery disconnect switches.
• The more subtle issue is that because the PV is an isolated DC circuit, that can be a voltage on the NEG wire relative to the RV frame and RV DC-. Thus, you should use a DC DPST switch and breaker with the proper (high) voltage and current rating.

I'm going to use a DC 2 Pole 1000V 32 Amp solar breaker, they are only $15.

As with many discussions, we often go down the rabbit hole over what works, vs. what we find the OEM wiring, NEC, RVIA, common sense, and best practice. I guess that is what makes the threads interesting and valuable. This is similar to the fusing discussion we had with the break-away brake wiring.