Ive got another idea brewing!

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The extremes are simple - RSD is required for PV on buildings and not for ground mounted PV - but the dividing line between where it is and is not required is not that clear to me.
Yeah, it's an interesting question. Under what conditions can you get away with calling a structure just a PV support structure and not a building? I have not delved into to what detail local building departments define the word "building". Perhaps one theory is that if it does not have a roof then it is not a building..... But then we are into whether the panels are a roof.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Not to derail your topic but in my personal experience rapid shutdown is junk that should not be relied upon.
Reason #1 there is no ongoing testing requirement after its installed (like a self test GFCI).
Reason #2 it relies on transistors or SSR's that can just short closed. I have more than a few times been able to measure voltages in excess of 300V DC with it 'off'.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Not to derail your topic but in my personal experience rapid shutdown is junk that should not be relied upon.
Reason #1 there is no ongoing testing requirement after its installed (like a self test GFCI).
Reason #2 it relies on transistors or SSR's that can just short closed. I have more than a few times been able to measure voltages in excess of 300V DC with it 'off'.
Ours is not to reason why; ours is to design and comply.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
How about Rapid Shutdown? The DC shutdown requirement for the array(s) on any roof top. Would that still apply when the Array IS the rooftop? If so, would you do individual shut-downs (DC, like Tigo) -- or Microinverters -- or Big Inverters, right in the "attic" . . . that might be cheapest?
The requirement applies on a building, not a roof. It would apply to anything that qualifies as a building regardless of whether the PV is on or is the roof. The array boundary is a little different practically speaking if it is the roof.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
The requirement applies on a building, not a roof. It would apply to anything that qualifies as a building regardless of whether the PV is on or is the roof. The array boundary is a little different practically speaking if it is the roof.
Rapid shutdown requirements are a bit murky. The 2020 NEC defines a building simply as "a structure that stands alone or that is separated from adjoining structures by fire walls"; that is pretty broad. In addition to what is considered a building, rapid shutdown requirements also differ according to which NEC cycle governs the installation.
 

tallgirl

Senior Member
Location
Great White North
Occupation
Controls Systems firmware engineer
Two words:

Covered Walkways.

Actually, anything that can benefit from being covered can benefit from being covered with solar. I tried convincing car dealerships they needed covered customer parking.

Nope! Didn't bite!

Glad I don't live in Texas right about now!
 

pv_n00b

Senior Member
Location
CA, USA
Not to derail your topic but in my personal experience rapid shutdown is junk that should not be relied upon.
Reason #1 there is no ongoing testing requirement after its installed (like a self test GFCI).
Reason #2 it relies on transistors or SSR's that can just short closed. I have more than a few times been able to measure voltages in excess of 300V DC with it 'off'.
RSD was a stopgap measure with UL 3741 PV Hazard Reduction being the long-term solution. As manufacturers launch UL 3741 listed systems expect to see a return to full string voltage inside the PV array being allowed. What's old is new again.
 
Just found some 54 cell 205 watt panels for $25 each. Thats $1.50/sq ft, the same price as metal roofing!
So an update. Those 205 watt panels for $25 each fell through. It was a long several month fiasco of not hearing from them after I paid for them, turns out the guy died. I guess he sold more panels than he had so I can't get them from the estate, they said they will give me my money back. Also metal roofing is cheaper than I thought, through fastener stuff is just $1.20 a square foot so I think I'm just going to do that and skip the solar back there.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
So an update. Those 205 watt panels for $25 each fell through. It was a long several month fiasco of not hearing from them after I paid for them, turns out the guy died. I guess he sold more panels than he had so I can't get them from the estate, they said they will give me my money back. Also metal roofing is cheaper than I thought, through fastener stuff is just $1.20 a square foot so I think I'm just going to do that and skip the solar back there.
Sorry that didn't work out for you. It's good you'll get your money back, but that doesn't take the sting out of the disappointment.
 
Sorry that didn't work out for you. It's good you'll get your money back, but that doesn't take the sting out of the disappointment.
Well it was a kind of crazy idea anyway but would have been kind of fun. It will certainly be quicker just putting up metal. Those panels were a killer deal, too bad I didn't see them before they were all gone. They're about half the price of anything else I found.
 
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