Solar disconnect and system labeling

[gklott]

NEC 690.13 lists requirements for disconnecting means for a PV system’s ungrounded DC conductors. 690.13(A), states that the “PV disconnecting means shall be installed at a readily accessible location either on the outside of a building or structure or inside nearest the point of entrance of the system conductors.”

Have considered possible locations for my BlueSea 6010 disconnect switch (dual circuit, both + and -, since - is ungrounded). This will disconnect the roof mounted panels.
- surface mount inside behind refrigerator, with access via the exterior refrigerator access/vent door, or
- front panel mounting into skin near the exterior refrigerator access/vent door, or
- front panel mounting into skin near adjacent to the new 50A SmartPlug receptacle, street side just forward of the wheels

Switch front panel mounting is clean and nice, but the trailer's skin thickness is ~ 2", and the panel mounting is designed for a 3/4" thickness. Would need a bigger opening on the inside skin to accommodate the wire lugs.

Where is everyone mounting their PV disconnecting device?

On labeling, where is everyone obtaining the MANY safety labels? Are you buying the solar label sheets from Amazon and other retailers?

73/gus

[pteck]

I just installed mine. Using a breaker switch on the positive leg, installed in the fridge compartment as my PV wires run down the vent.

I also added a label there (with home label maker), noting the PV shutoff. Also added a label to the battery compartment box to remind me to disconnect the PV shutoff before disconnecting the batts.

[gklott]

Originally Posted by pteck

I just installed mine. Using a breaker switch on the positive leg, installed in the fridge compartment as my PV wires run down the vent. I also added a label there (with home label maker), noting the PV shutoff. Also added a label to the battery compartment box to remind me to disconnect the PV shutoff before disconnecting the batts.

Thanks.

Maybe I missed it in your picture, but did you run a separate negative lead from the combiner box to your charger? Otherwise, do you have all the - leads grounded to the trailer's skin at the solar panel, at the combiner box, or where?

I ran a dedicated 6 AWG negative wire to the combiner box. The only point where our PV system's negative lead becomes "grounded" is at the solar charger, since the battery negative bus is also grounded to the trailer's skin/frame and to the AC system grounding conductor.

How are you labeling on the trailer's exterior for fire department, etc? PV systems are BIG life-safety hazards should there be an emergency at the trailer.

73/gus

[pteck]

My setup is certainly not to the rigor that you're looking for. So the shutoff only separates the positive lead, and I'm not grounding anywhere else other than at the solar controller.

My goal was to have a reasonable and safe installation per typical best practices for a travel trailer. Looks to me that majority of the installations don't even bother with a PV cutoff switch or additional fusing which I've added where necessary.

[gklott]

The 2014 RVIA low voltage standard and the 2015 NFPA 1192 RV standard have no mention of solar or photovoltaics. The RVIA LV standard para 2-1 doesn't yet list photovoltaics as a possible power source.

This is a major hole in both, and hopefully the next versions will require RVs to follow NEC Article 690.

Would hate to be a first responder working a fire in a solar-equipped Airstream without the safety labeling and external disconnect.

73/gus

[SSquared]

My setup (done by Lewster in 2014) has a combiner box on the roof, dual strand cable down the fridge vent and through the interior to the right front where there is a disconnect on the + side, and then to the solar controller. Then a short run down of the + wire through the floor to another disconnect underneath and then to the battery box. Of course there is a - wire from the solar controller, which goes to the common ground connection a few inches away.

I'm not sure what, if any, fuses exist in the solar wiring.

Gus, what makes you say RV solar systems are a "BIG" life safety issue? Mine tops out at about 20 volts (DC), unlike residential ones which sometimes are 120 volts (AC) (or maybe 240? not sure). My amperage can go up to 25 or 30 so it has potential for making some heat or spark, but not as much as the trailer batteries or the shore power.

[WayneG]

In my DIY method, I installed separate wires from each panel into the the MH and they join together via low voltage aircraft circuit breakers:

This way I can deactivate any panel(s) individually that I want, allowing me to test panel output or bypass a shorted panel (Which should happen automatically if the shorted panel exceeds the breaker rating)
Only down side to this is the added resistance of the circuit breaker, but it is minimal with the low voltage aircraft breakers I used.

[gklott]

Originally Posted by SSquared

Gus, what makes you say RV solar systems are a "BIG" life safety issue? Mine tops out at about 20 volts (DC), unlike residential ones which sometimes are 120 volts (AC) (or maybe 240? not sure).

The reason for saying "BIG" is there is an unidentified power source. A fire responder expects a battery, but without exterior marking, the responder might not expect a solar power source. Confusion would ensue when there is a power source still on after disconnecting the battery.

That's the last thing a responder needs - surprises.

If designed with one DC bus (charge and load), connecting a smaller inverter (say 300W) and solar charger, there may be 120VAC present without the battery. That's also a potential hazard.

So we put "solar power on roof" caution labels on street and curb side, and we have a labeled solar disconnect switch. Safety labeling is what I've seen that many RV solar systems lack, yet it is simple and inexpensive, via Amazon, to apply.

Our system has 1 panel in each of 6 strings for 750W, with each panel characterized at 27 Voc, 6 Asc. We use a 60A Morningstar MPPT charger with their solar ground fault protection device.

Unfortunately, NFPA 70E Table 130.7(C)(15)(b) does not yet specify personal protective equipment requirements for our solar systems if < 100V. NFPA 70E, NFPA 1192, RVIA LV, and ABYC E-11 are behind the times, like the Solar Photovoltaic (PV) Systems NEC article 690 was 4 or 5 versions ago.

73/gus