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Thread: Do I need Rapid Shutdown?

  1. #1
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    Do I need Rapid Shutdown?

    Here is the situation:

    PV on a single story roof. The string inverter will mount directly below the PV array on the wall of the building. I will penetrate through the eave of the roof to bring the conduit from the array to the inverter without entering the building.

    The distance from the inverter to the array will be less than 10 feet.

    Do I need Rapid Shutdown here? I seem to remember something about if the inverter was located within 10 feet of the array it was not required....? Any input appreciated, Thanks.

  2. #2
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    Probably not, I'm assuming you are referring to the 2014 NEC and this is a standard grid-tied PV system. The only problem you might have is that I have heard of some AHJs saying that running the conduit through the eave is the same as penetrating the building and then popping back out to the inverter, it's worth double-checking.

  3. #3
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    I will advise you that the way you are asking this question could be misunderstood. When I hear, "do I need rapid shutdown?", what I interpret is, "does the rapid shutdown rule apply?". The rapid shutdown rule certainly applies due to it being on a building.

    What you really are asking, is "do I need rapid shutdown specific equipment?", and in which case the answer is no, assuming 2014 applies. 2017 has a stricter limit of 1 ft, which is much more difficult to do with an inverter. The reason no rapid shutdown-specific equipment is needed is that the inverter and master disconnect accomplish the requirements of the rapid shutdown rule, without any DC balance of systems equipment for the rapid shutdown purpose being needed.

  4. #4
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    True, the OP did not phrase their question well. So yes you do need rapid shutdown but do you need anything in addition to what you had in mind to have rapid shutdown covered? Probably not.

    Even in the strictest interpretation of 2017 NEC rapid shutdown with the 690.12(B)(2) requirements in force, it will still be possible to build a compliant system without using additional equipment specifically for rapid shutdown. Any grid-tied system without backup that uses micro-inverters or DC optimizers will be inherently compliant. Most likely this is the direction the industry will have to go after Jan 1, 2019.

  5. #5
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    Thanks for responding even though it was unclear. I talked to my AHJ and he made it clear that we are following 2017 in our area, which has a stricter set of guidelines for rapid shutdown than 2014. Where the DC conductors have to be controlled is much closer to the array field than I had thought. Thanks again.

  6. #6
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    Quote Originally Posted by bbartmasse r View Post
    Thanks for responding even though it was unclear. I talked to my AHJ and he made it clear that we are following 2017 in our area, which has a stricter set of guidelines for rapid shutdown than 2014. Where the DC conductors have to be controlled is much closer to the array field than I had thought. Thanks again.
    What inverter are you using?

  7. #7
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    Quote Originally Posted by bbartmasse r View Post
    Thanks for responding even though it was unclear. I talked to my AHJ and he made it clear that we are following 2017 in our area, which has a stricter set of guidelines for rapid shutdown than 2014. Where the DC conductors have to be controlled is much closer to the array field than I had thought. Thanks again.
    Most people are switching to something with DC optimizers or microinverters to comply with 2017 at this point. In the future, there might be other options.

  8. #8
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    Quote Originally Posted by baserunner4 View Post
    What inverter are you using?

    We've been using a lot of SolarEdge, but have had only problems with their new stuff. So recently we've switched back to normal old string inverter with a rapid shutdown box on the roof.

    I don't trust those things either, so hence the question whether I need the equipment or not. I'd much rather avoid this fancy equipment all together.

  9. #9
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    It's all fancy, it's low volume, it's buggy, and in many instances new products are released in beta condition because manufacturers are applying the Agile software development system to hardware.

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