PV disconnect required?

[Electrobe]

Is a PV disconnect required for a single 100W module in a stand alone system? Just have a small DC load with a 12VDC car battery for backup.

Thanks in advance

 

[pv_n00b]

I guess it kind of depends on what you are doing and where it is installed. A small system like this would not seem to have any particular code requirements.

 

[Dennis Alwon]

This sections seems to require a disco.

690.10 Stand-Alone Systems. The premises wiring system
shall be adequate to meet the requirements of this Code
for a similar installation connected to a service. The wiring
on the supply side of the building or structure disconnecting
means shall comply with the requirements of this Code,
except as modified by 690.10(A) through (E).

I have not seen any exceptions to the rule however I am not a pv guy

690.15 Disconnection of Photovoltaic Equipment. Means
shall be provided to disconnect equipment, such as inverters,
batteries, and charge controllers, from all ungrounded
conductors of all sources. If the equipment is energized
from more than one source, the disconnecting means shall
be grouped and identified.

 

[GoldDigger]

Is a PV disconnect required for a single 100W module in a stand alone system? Just have a small DC load with a 12VDC car battery for backup.

Thanks in advance

What do you mean by a PV disconnect? The term seems to be most often used to refer to the AC disconnect in a grid interactive system.
In your case the only possibility would be a disconnect between the panels and your DC load and charge controller. If the whole system is outside a building I do not see the necessity. If the panels are outside and the rest of the system is inside, you may well need a DC disconnect.

 

[Dennis Alwon]

What do you mean by a PV disconnect? The term seems to be most often used to refer to the AC disconnect in a grid interactive system.
In your case the only possibility would be a disconnect between the panels and your DC load and charge controller. If the whole system is outside a building I do not see the necessity. If the panels are outside and the rest of the system is inside, you may well need a DC disconnect.

Where is that exception in art. 690.15... Just curious

 

[GoldDigger]

Where is that exception in art. 690.15... Just curious

I don't see it there either, but the size of the OP's system says to me that it might not even be associated with a building. (But anything is structure, I know....) Quite likely no permit involved. In terms of safety, given the low voltage of one panel and the strictly limited current, I do not see a need.
The MC4 or other connectors in the panel wiring can serve as an isolating disconnect even if they are not rated for load breaking.

 

[jaggedben]

I'm inclined to agree that the code requires a disconnect for anything that's actually installed and not a portable setup. At 12V one could probably use automotive hardware or a connector that complies with 690.33. No need for a 30A safety switch.

The battery also requires a disconnect and is a probably bigger safety concern than the solar module.

 

[GoldDigger]

The battery also requires a disconnect and is a probably bigger safety concern than the solar module.

:thumbsup::thumbsup:
In addition to a disconnect there absolutely must be some kind of OCPD for the battery. For greatest safety a fuse mounted right on one of the battery terminals is ideal. If the OP can find a suitable DC rated breaker he could combine the OCPD and disconnect functions in one unit.

 

[Electrobe]

I don't see it there either, but the size of the OP's system says to me that it might not even be associated with a building. (But anything is structure, I know....) Quite likely no permit involved. In terms of safety, given the low voltage of one panel and the strictly limited current, I do not see a need.
The MC4 or other connectors in the panel wiring can serve as an isolating disconnect even if they are not rated for load breaking.

This system is powering a weather station in a remote location. The controller is a small 10Amp, 12V controller with Solar and battery inputs and a load output. Currently there is no fusing or any disconnects on anything. We are planning on adding some additional load so we are looking at increasing the solar panel from 10W to 100W. Wanted to bring the system up to the latest NEC codes since we were making these changes. Was not sure if the NEC section 690 applied since it was only a 12VDC system but I could not find any exceptions. There are no MC4 connectors on the new or old solar panel but they could be added if this would be a good solution for the required disconnect.

Since this is a 12VDC system I was planning to add type ATC auto type fuses to the battery and load outputs but was not sure about the solar input since it is current limited. Does the NEC apply to this installation? if so, do we need to add disconnects to the battery and solar inputs? Can the auto type fuse be used as the disconnect? Many questions that I cannot determine from reading section 690.

Thanks

 

[jaggedben]

I would say technically the NEC applies. The only exception to 690 rules that I think applies is if the whole unit comes as listed assembly and you install it according to the instructions, then you are covered by 110.3(B). But if there's any field installed wiring, or you assembled the components from disparate sources, then 690 rules apply.

Practically speaking, the safety concerns could be:

1. Can anything about the system start a fire? If it's in a high fire danger area, this could be important even if it isn't on a building.
2. Can someone servicing the apparatus do so safely.

The disconnect is about (2). At 12V maybe the rules are overkill, but yeah, there's no exceptions.

The fuse is about (1). I completely agree with iwire's post about the fuse for the battery. This is important.

Because it's not on a dwelling you are fortunately excused from having to have GFDI.

 

[GoldDigger]

Since this is a 12VDC system I was planning to add type ATC auto type fuses to the battery and load outputs but was not sure about the solar input since it is current limited.

As long as you have two or fewer panels or strings of panels in parallel you do not need to fuse the DC input from the panels. But if you do not fuse the DC input you should make sure that the fusing for the battery and the charge controller will collectively protect the panel wiring in the event of a short inside the charge controller that applies battery voltage directly to the input wires.

 

[ggunn]

This system is powering a weather station in a remote location. The controller is a small 10Amp, 12V controller with Solar and battery inputs and a load output. Currently there is no fusing or any disconnects on anything. We are planning on adding some additional load so we are looking at increasing the solar panel from 10W to 100W. Wanted to bring the system up to the latest NEC codes since we were making these changes. Was not sure if the NEC section 690 applied since it was only a 12VDC system but I could not find any exceptions. There are no MC4 connectors on the new or old solar panel but they could be added if this would be a good solution for the required disconnect.

Since this is a 12VDC system I was planning to add type ATC auto type fuses to the battery and load outputs but was not sure about the solar input since it is current limited. Does the NEC apply to this installation? if so, do we need to add disconnects to the battery and solar inputs? Can the auto type fuse be used as the disconnect? Many questions that I cannot determine from reading section 690.

Thanks

The only suggestion I would have is to rethink the use of a car battery. Car batteries are designed to deliver a lot of current over a short period of time whereas batteries typically used in solar applications are designed to deliver lower currents over extended periods of time. I think you should investigate 12V batteries designed for solar (or golf carts).

 

[Electrobe]

The only suggestion I would have is to rethink the use of a car battery. Car batteries are designed to deliver a lot of current over a short period of time whereas batteries typically used in solar applications are designed to deliver lower currents over extended periods of time. I think you should investigate 12V batteries designed for solar (or golf carts).

I agree the controller manufacturer brought up the same point! Thanks for the feedback!

 

[pv_n00b]

This system is powering a weather station in a remote location. The controller is a small 10Amp, 12V controller with Solar and battery inputs and a load output. Currently there is no fusing or any disconnects on anything. We are planning on adding some additional load so we are looking at increasing the solar panel from 10W to 100W. Wanted to bring the system up to the latest NEC codes since we were making these changes. Was not sure if the NEC section 690 applied since it was only a 12VDC system but I could not find any exceptions. There are no MC4 connectors on the new or old solar panel but they could be added if this would be a good solution for the required disconnect.

Since this is a 12VDC system I was planning to add type ATC auto type fuses to the battery and load outputs but was not sure about the solar input since it is current limited. Does the NEC apply to this installation? if so, do we need to add disconnects to the battery and solar inputs? Can the auto type fuse be used as the disconnect? Many questions that I cannot determine from reading section 690.

Thanks

If you want it to be NEC compliant then yes you need a DC disconnect between the module and the charge controller so you can service the charge controller. The form that disconnect takes can be a switch or a connector. I would use a connector.