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PV-SAFE and PV-Off button - Installing a Manual Latching Push Button Safety Switch

  • Updated

This article discusses the installation of a PV-Safe and PV-Off to signal the MLPE to disconnect their panels from the strings.

Tigo has called this PV-Safe and PV-Off. It is similar to a Rapid Shutdown except powering off of the Data Logger (Cloud Connect, Cloud Connect Advanced, or Maximizer Management Unit) is not required. Note that you may achieve the same effect by disconnecting power to the Data Logger.

 

Contents: 


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Switch/Button Overview

All models of Tigo Management Devices (i.e., Data Loggers) offer a PV-Off solution for manual DC-Disconnect at the PV Module level using a Normally Open switch that latches or uses a key.

 

When the button is pressed, the latching mechanism will lock the button which connect a pin of the AUX terminal to ground. The management device then issues a command all MLPEs to disconnect themselves from the DC Circuit, which will de-energize the string within 30 seconds. Power production will only resume upon releasing, unlatching, or returning the switch to its Open position (AUX terminals no longer connected).

Latching Push Button

The below pictured device is de-activated (not in panel disconnect PV-Safe mode) when it is out. When pressed, the button latches in the activated position. Release the button by turning clockwise.


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Disclaimer: The button shown above is a standard off-the-shelf item (not included with Tigo purchase). Your choice of buttons should have these features:

  • Operation mode: Normally Open (NO) button
    In most cases, NO or NC operation can be configured within the switch housing.
  • Latching mechanism: Button must have latching mechanism (twist to release, key lock, etc.)

 

Types of Systems

Any TS4 model that is capable of PV Module (solar panel) disconnect, offers an automatic Rapid Shut Down (RSD) response as well as a manual PV-Off option. Each function will disconnect the panel from the string wiring (resulting in a total DC-Loss (0 Volts DC) to the Inverter), but the PV-Off is sometimes easier to manage. Without a PV-Off enabled switch/button, the data logger requires an autonomous RSD response to shut down. This means that the Tigo System must experience a full AC-Loss, in order to be effectively powered off.

TS4 models capable of module-level disconnect are:

  • Safety - TS4-S, TS4-R-S, TS4-A-S
  • Optimizer - TS4-O, TS4-R-O,  TS4-A-O
  • Long String - TS4-L

TS4 models that are not capable of module-level disconnect are: 

  • Diode Only - TS4-D
  • Monitoring Only - TS4-M, TS4-R-M


A E Stop (PV-Safe activation) Switch can also be installed on the Tigo Fire Safety model systems (which use PLC signaling over the string wiring). In these cases, you would attach the switch to the top row right most and the other end to the power supply Negative wire. Note this feature is deprecated on newer Tigo RSS transmitters.

For activating a manual PV-Off pane disconnect from older Legacy systems, see our article on PV-Safe

 

Connecting a Switch to the Cloud Connect Advanced

When viewing the wiring ports on the CCA, the AUX terminals are located on the left side. This left side terminal is not grounded for normal operation of the system.

 

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A single pole switch is all that is required.

The switch poles are connected to the terminals. When the switch is Open, the left side terminal will have 3.3 VDC. This is good to know when troubleshooting any wires/cables in use.

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Note: The original generation of CCA did not include the protocol for PV-Off and required a software update to support this feature. If you have installed a button and it does not function as expected (PV modules are not disconnecting from strings), please contact the Tigo Support Team and state you are installing a switch to initiate PV-Off, and require the necessary service update. 

 

How to Wire Multiple Data Loggers to a single Shut-off Button

Up to 5 data loggers can be connected to a single switch.

For a shutoff button to work on multiple data loggers, each logger must be connected to the shutoff button on its own individual wires that run point to point from the switch, not daisy-chained in parallel.

  • Be sure to connect the right hand side terminals, and the left hand (3.3 VDC) wires together, as shown in the diagram below.
  • No outside-source voltage MAY EVER be placed on the AUX port (voids Warranty)
  • The ground of the system should be connected to the 24 VDC "-" Negative terminal
  • The left-hand pin should read close to 3.3 VDC when the switch is OPEN. 0 VDC when the switch is CLOSED (activated)
  • When connecting multiple CCAs to the same switch be sure that the maximum distance between the shut-off button and the first CCA is under 100 meters.
  • Additional CCA's also must be less than 100 meters apart from each other

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Cautions and Disclaimers

Here are some very important things to remember about PV-Off activation:

  1. During installation of any switch, relay or button, please follow all safety precautions 
  2. DANGER: Prior to servicing a system, please use a voltmeter to confirm that neither voltage nor current are present and flowing through the PV array after having pushed the external shutdown button.
  3. External mushroom buttons are a convenient way to disconnect the DC Side of a system, but they are not necessarily considered NEC 690.12 2014 or 2017 compliant; please always follow NEC required procedures and consult with your local authority, to provide the appropriate means of disconnection and signage to emergency personnel.

 

Legacy Products

Tigo Legacy products (MMU and Cloud Connect) offer a PV-Safe solution (the predecessor to PV-Off). They included a PV-Safe button on the Data Logger, but also offered a similar terminal interface for adding a manual latching push button safety switch.

To read more about PV-Safe, go to: What is PV-Safe, and How do I Re-Activate my System?

 

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