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Field Notice Rapid Shutdown Verification: Why the Array May Remain Energized After Turning Off the CCA

  • Updated

Summary

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Installers using the TS4-X and the new TS4-A (725W) with third-party inverters that have integrated Tigo RSS Transmitters (or third-party RSD transmitters) need to be aware of an important safety consideration.


Even if the Cloud Connect Advanced (CCA) is powered down, full array voltage may still be present. This can create a shock hazard if installers assume the system is de-energized when it is not.

Also, all TS4-X and TS4-A (725W) products are shipping in the ON position. This means full module voltage will pass as soon as these TS4s are connected to the module. 

Always exercise proper electrical safety practices and wear appropriate PPE when installing or servicing these units.

Relevant TS4 Units

MLPE_Device_TS4-X-O-102024_1.jpg

TS4-X-O
MLPE_Device_102024_1.png

TS4-X-S
MLPE_Device_TS4-X-F_102024_1.jpg

TS4-X-F
TS4-A-O 725W front.png

TS4-A-O (725W)
TS4-A-S - 725W - front.png

TS4-A-S (725W)
TS4-A-F - 725W - front.png

TS4-A-F (725W)
Non-725W TS4-A units will only have 4 cable glands on the bottom of the unit, except for the TS4-A-2F, which also has 6.
TS4-A-O outlined Hi Res_cropped.png

 

Background

The TS4-X and TS4-A (725W) products include a multifactor rapid shutdown (RSD) feature:

  • TS4 devices can receive keep-alive signals from more than one source.
  • A compatible integrated RSS Transmitter may continue providing a keep-alive signal after the CCA is turned off.
  • As a result, the PV array may remain energized until all keep-alive signals are removed.

This behavior is expected and allows compatibility with multiple Rapid Shutdown methods. 

Schematic - X-O - MFRS 2.png

Safety Guidance

  1. Do not rely solely on turning off the CCA to de-energize a system when using third-party inverters with integrated RSS.
  2. Always verify voltage at the array conductors with a properly rated meter before touching or servicing.
  3. If working on the DC side, isolate PV circuits at the combiner, disconnects, or breakers before handling conductors.
  4. Train all crew members that CCA OFF ≠ Array OFF in this configuration.

To ensure Rapid Shutdown is initiated and the PV array is de-energized:

  • Turn off the Cloud Connect Advanced (CCA).
  • If the system includes a third-party RSS Transmitter, follow the inverter manufacturer's instructions to disable or remove its keep-alive signal. Procedures vary by manufacturer.
  • Use a compliant Rapid Shutdown initiator, where applicable, to remove all active keep-alive signals.
  • Verify the PV array is in the expected Rapid Shutdown state before performing any work.

Important: If a third-party RSS Transmitter remains active, the TS4-X and TS4-A (725W) devices will continue receiving a valid keep-alive signal, and the PV array will remain energized regardless of CCA status.

 

Key Takeaway

When paired with inverters that include their own RSS Transmitters, the TS4-X and TS4-A (725W) will remain active as long as they detect the PLC signal—even if the CCA is turned off. Installers must take this into account during design, commissioning, and service to avoid shock hazards.

Questions

Contact Tigo Customer Success with questions.

Additional Information

Multi Factor Rapid Shutdown Overview

Safety Notice: TS4-X & TS4-A (725W) Ship in the ON State

 

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