1000V strings residential

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electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
This seems like it would have been covered before, but I couldnt find much on it. What is your opinion and experience on 1000V strings on "residential property" but not on a dwelling building? Say the array is ground mount or on a detached structure that isnt a dwelling. It seems to me it just comes down to the AHJ's interpretation of 690.7(C), or is there more to it?
 
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ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
electrofelon said:
This seems like it would have been covered before, but I couldnt find much on it. What is your opinion and experience on 1000V strings on "residential property" but not on a dwelling building? Say the array is ground mount or on a detached structure that isnt a dwelling. It seems to me it just comes down to the AHJ's interpretation of 690.7(C), or is there more to it?
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1000V strings are permitted on anything that is not a 1 or 2 family dwelling. Shortcircuit's comment points out a clarification in the 2017 code, not a change; I don't know of anyone who interprets 690.7(C) to mean that you can have 1000V strings on a single or duplex dwelling as long as no DC conductors penetrate the building.

PV systems on detached garages and ground mounted arrays next to such structures can be 1000V as long as the DC conductors do not touch the dwelling, i.e., as long as the inverter(s) are mounted on the garage or at the GMA.
 
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Carultch

Senior Member
Location
Massachusetts
electrofelon said:
This seems like it would have been covered before, but I couldnt find much on it. What is your opinion and experience on 1000V strings on "residential property" but not on a dwelling building? Say the array is ground mount or on a detached structure that isnt a dwelling. It seems to me it just comes down to the AHJ's interpretation of 690.7(C), or is there more to it?
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Do you know of any inverter or other power processing equipment, that can work with 1000Vdc and single phase?


Unless you've got a three phase service at a residence, which is a rare scenario, this is much more of a theoretical question than a practical one.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Carultch said:
Do you know of any inverter or other power processing equipment, that can work with 1000Vdc and single phase?


Unless you've got a three phase service at a residence, which is a rare scenario, this is much more of a theoretical question than a practical one.
Click to expand...

Yes, fronius primo single phase inverters can. I just realized this last night and was surprised.
 
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pv_n00b

Senior Member
Location
CA, USA
Keep in mind the AHJ could consider any part of the PV system contacting the home to mean that the PV system is "on or in" the home. That could very well include the AC connection to the service entrance. There is no positive isolation between the PV array and the AC wiring in transformerless inverters. While it's unlikely that the AC conductors would become energized to the DC voltage it's not impossible. So don't assume it's a slam dunk, check with the AHJ before installation.
 
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