Rapid shutdown

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Shawn McCaslin
 
I am trying to understand how rapid shutdown works with the TS4-A-O modules.
  • Can I initiate rapid shutdown from within the Tigo app?  Can I see the current rapid shutdown state from within the app?
  • Rapid shutdown is triggered by loss of CCA signal to the TAP.  How do I disable this feature?  Can I optionally program the system to not shutdown when the CCA signal is lost?  Since the CCA/TAP is optional with selective deployment, I assume that by default, modules do not expect to see the CCA/TAP signal.
  • Shutdown can be triggered by loss of power at the CCA, or by the AUX input on the CCA.  Can I configure the system to recognize just the AUX input to control rapid shutdown?
  • I think that NEC requires manual restart after a rapid shutdown has been initiated.  What if I have a utility-caused loss of power at my house, which causes the CCA to lose power, triggering a rapid shutdown?  Will the system come back on-line automatically when power is restored, or must I manually restart the system?
  • Are rapid shutdown events logged in the system?
  • Can I get push notifications when a rapid shutdown event is initiated?
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  • Avatar
    Curtis Community Moderator Tigo Employee

    Hello Shawn, 

    Thank you for participating in the Tigo Community!

    My apologies for the delay in response. Here are the answers to your questions.

    • Can I initiate rapid shutdown from within the Tigo app?
      No, rapid shutdown (RSD) is an NEC-required 'automatic' response to grid loss. It must happen without any manual assistance from the app, or other devices. This provides the needed safety measures for first responders. Also, the lack of RSD Control (in the app), prevents system owners and/or installers from accidentally activating or deactivating a system without knowing the safety conditions of the onsite workers. 
    • Can I see the current rapid shutdown state from within the app?
      No, the Tigo EI App cannot receive an RSD notification from the CCA since the CCA will be powered down for the rapid shutdown event.  However, the EI App will show a production loss during that period.
    • Rapid shutdown is triggered by loss of CCA signal to the TAP.  How do I disable this feature? 
      The CCA rapid shutdown feature cannot be disabled. Disarming the RSD functionality of the Tigo MLPE's would void your system from being approved by your local AHJ (authority having jurisdiction). Please Contact Tigo's Support Team to inquire about liability options for your system.

    • Since the CCA/TAP is optional with selective deployment, I assume that by default, modules do not expect to see the CCA/TAP signal.
      First, the CCA and TAP are not optional components with regard to rapid shutdown operation. The communication coming from the CCA/TAP includes a "keep alive" signal. When that signal is lost, the system goes into RSD. Installing Tigo MLPE's without CCA/TAP is considered Blind Deployment (not Selective Deployment). This method is not supported by Tigo, and it will also affect your system's eligibility for Warranty Coverage. 

      To learn more about the different deployment methods: TS4 Systems - Methods of Deployment

    • Can I configure the system to recognize just the AUX input to control rapid shutdown?
      Controlling the Aux Input is called PV-OFF and will trigger the rapid shutdown behavior. The CCA would be connected to a disconnect or turn off (690.12(C))at the same time the PV inverter would shut down if using a PV system disconnect, so I am not sure what you are asking. If the CCA loses power from any source it will engage the TS4 rapid shutdown behavior.

      To learn more about PV-OFF: Installing a Manual Latching Push Button Safety Switch
    • What if I have a utility-caused loss of power at my house, which causes the CCA to lose power, triggering a rapid shutdown?  Will the system come back on-line automatically when power is restored, or must I manually restart the system?
      Once the CCA receives power, then the TS4 will return to normal opening condition since they will receive the keep alive signal.
    • Are rapid shutdown events logged in the system?
      RSD events are not logged specifically logged since the CCA cannot send data to the EI Portal or App without power.  An RSd event would look similar to a grid outage. However, if your system is down for more than a couple mins, you will see that all of the PV-Modules turn grey (in System View > Layout) during the AC-Loss event and the system production will have ceased for that period of time.  
    • Can I get push notifications when a rapid shutdown event is initiated?
      There is no RSD specific Alert because the AC-Grid loss shuts down the CCA. 

      To learn more about Alerts: What do the Alerts Mean?

    For more information on your local rules and regulation, please contact your local AHJ. If you require more information about RSD, PV-OFF and/or how Tigo meets the NEC required criteria, please feel free to reach out to our Sales/Training Engineers, or Contact our Support Team. 

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  • Avatar
    Jesse Campbell

    Just as a note, regarding your question "Can I get push notifications when a rapid shutdown event is initiated?":
    My system is set up such that turning off the solar service disconnects while the grid is still powered up triggers rapid shutdown via the aux input. I *do* get a text/push notification for the PV-OFF trigger like this.

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    Curtis Community Moderator Tigo Employee

    Jesse Campbell

    Interesting... Please confirm:

    • When you say that RSD is triggered via the Aux Input, are you stating that the CCA is connected to a manual button or relay? 
    • When you receive these reports, they are on Tigo's Page (not on another service like an inverter page)? 
    • What does the Alert say?

    Thank you for your insight!

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  • Avatar
    Jesse Campbell
    • Edited

    My inverter has a constant 12V (or was it 24? I can't remember) output when it has grid power, and there was no straightforward way to power the CCA from the grid feed that passes through the solar service disconnects without an extensive rewiring of the electricals, so my electrician tied the 12V output to a relay to trigger the PV-OFF aux input. It will trigger when the inverter loses power, or if the grid goes down completely, as the relay is "normally closed" and requires power to stay open.

    The alerts do go to both the Tigo EI website, and I get alerts on my phone via text message. When we were having the second inverter installed over the past couple of weeks, there were a few changes so there were a few PV-OFF actions. Here's what my alerts dashboard looks like today:

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  • Avatar
    Curtis Community Moderator Tigo Employee

    Hello Jesse, 

    Thank you for your concise response and attached image!

    Rapid Shut Down (RSD) and PV-OFF are very similar functions, but different in definition: 

    RSD is an automated response to AC-Loss, that shuts down the DC side of the system, once the CCA loses AC power. Since there is no power supplied to the CCA, it cannot generate a report to the System Owner's account. 

    PV-OFF is a manual response to a latch, switch, relay or other device, that provides a result that is similar (DC system voltage output reduced to zero, within 30 seconds), but is not considered RSD. Since the CCA is still receiving AC power during a PV-OFF event, it can send a notification to your account.

    Click here for more information on PV-OFF and how it operates:
    PV-Off - Installing a Manual Latching Push Button Safety Switch

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