Faceplate between roof and panel

[SunEagle]

Which code is going to require Total Panel Disocnnection? Do you have a link. The most recent code I'm familiar with is NFPA70 / NEC 2014 which requires "Rapid Shutdown"

Thanks

Andy

I believe NEC 690.12 "Rapid Shutdown" mentions that energized wires that are longer than 10ft from a PV array are to be reduced to not more than 30 volts and 240 VA within 10 seconds of the rapid shutdown initiation.

Most PV systems that incorporate a "string" of panels wired to the inverter will see voltage much higher than 30v. Which to me means that the power has to be disconnected or reduced to 30v at each panel and not at the Inverter. So unless the panels are each rated 30v max and are all wired in parallel, you will be required to use a Micro-inverter or something similar to shut down the power coming from the panel within 10ft of the panel.

Maybe I am reading this wrong but I thought to protect the Fireman that are on your roof, all PV wires need to be de-energized or reduced to 30volts to eliminate any potential of being shocked or electrocuted.

[Wy_White_Wolf]

It's 10' from the array. So you don't need to disconnect/reduce every panel. Just every string within 10' of the array.

WWW

[SunEagle]

It's 10' from the array. So you don't need to disconnect/reduce every panel. Just every string within 10' of the array.

WWW

That would also work but would require some type of automated disconnect switch to de-energize each "string" and would have to be mounted on the roof or on the building wall within 10ft of the edge of the array. It might be easier to just put in micro inverters.

[bcroe]

That would also work but would require some type of automated disconnect switch to de-energize each "string" and would have to be mounted on the roof or on the building wall within 10ft of the edge of the array. It might be easier to just put in micro inverters.

Wouldn't using micro inverters just replace high voltage DC on the roof, with
high voltage AC? Is that a solution?

What drives an "automated disconnect switch"? Seem like we want things that
default to a safe mode (broken wires, power off, etc), how will this function?

Bruce Roe

[sdold]

Wouldn't using micro inverters just replace high voltage DC on the roof, with
high voltage AC? Is that a solution?

Yes, but when the firemen pull the meter, the microinverters shut down. The only power left is the DC from the panel to the microinverter.

What drives an "automated disconnect switch"? Seem like we want things that
default to a safe mode (broken wires, power off, etc), how will this function?

I think a contactor at the panels would be a simple way to disconnect both poles in a DC system to render them safe(er). It would be easy to do by just powering the coil from AC power from the main panel. If the meter is pulled, the array is disconnected at the array and the rest of the wiring is de-energized. It looks like this may be close to what I'm talking about:

http://www.solarbos.com/data/files/19/2014%20SolarBOS%20Contactor%20Combiner.pdf

[bcroe]

I think a contactor at the panels would be a simple way to disconnect both poles in a DC system to render them safe(er). It would be easy to do by just powering the coil from AC power from the main panel. If the meter is pulled, the array is disconnected at the array and the rest of the wiring is de-energized. It looks like this may be close to what I'm talking about:

http://www.solarbos.com/data/files/1...20Combiner.pdf

That looks very expensive and uses power continuously. Or could be a latching relay, but
then would not be fail safe. Think it would take 2 of them here.

Is it located by the combiner box to disconnect each string; if so the hazard is not removed?
Or does it disconnect individual panels; I'm trying to imagine the spider web of wires that
would take, all out doors? Bruce Roe

[SunEagle]

That looks very expensive and uses power continuously. Or could be a latching relay, but
then would not be fail safe. Think it would take 2 of them here.

Is it located by the combiner box to disconnect each string; if so the hazard is not removed?
Or does it disconnect individual panels; I'm trying to imagine the spider web of wires that
would take, all out doors? Bruce Roe

If the combiner boxes were within that 10ft limit required by the NEC then you could isolate a number of strings using a single multi point contactor and minimize shock exposure to any First responders that are on your roof outside that 10ft limit. Depending on the size of the PC array it would still require at least another box and control cable to perform the "shutdown".

You would need to add this extra equipment to meet code if you used the standed String Inverters but with mico inverters at each panel they would perform the shutdown when they were disconnected from the Grid.

I am just looking for opinions on how the manufacturers of String Inverters will be able to meet the new part of the NEC.

[PVAndy]

That looks very expensive and uses power continuously. Or could be a latching relay, but
then would not be fail safe. Think it would take 2 of them here.

Is it located by the combiner box to disconnect each string; if so the hazard is not removed?
Or does it disconnect individual panels; I'm trying to imagine the spider web of wires that
would take, all out doors? Bruce Roe

NEC 2014 "Rapid Shutdown" does not require shutting off the power at each panel, only within 10 feet of the array.

Besides microinverters and optomizers, you can mount the inverter within 10 feet of the array. Other existing solutions include the MidNite Solar Birdhouse Emergency Disconnect Switch

There are also several other remote operated DC disconnects on the market.

Andy

[SunEagle]

NEC 2014 "Rapid Shutdown" does not require shutting off the power at each panel, only within 10 feet of the array.

Besides microinverters and optomizers, you can mount the inverter within 10 feet of the array. Other existing solutions include the MidNite Solar Birdhouse Emergency Disconnect Switch

There are also several other remote operated DC disconnects on the market.

Andy

I agree that there may be many ways to meet code. Say on average an 8kw systems has about 30 panels. Usually they are wired in strings that run much farther than 10ft to the String Inverter. Usually that inverter is on a wall way below the roof mounted array.

So you would need a way to disconnect a "string" within the 10ft limit. That would require additional hardware that is not installed on a standard String Inverter system. From what I have read the MidNite Solar Birdhouse equipment would do the job.

Another way to meet the code would be to disconnect power at the panel using micro inverters.

[englert123]

If you are installing the solar panel in your roof you might face different problem like insulating problems etc. This type of problem can be easily removed by placing a faceplate between roof and panel. This work becomes easier if the design of metal roof (link to metal roof manufacturer removed) was known.

--Mod note: especially on your first post, do not include links to commercial sites to small to trivial posts. This is your only warning.