Supported Testing Methods for TS4 MLPE Systems – Tigo Help Center

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Testing Methods
Monitored Systems
Rapid Shutdown Only Systems
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Overview

A Tigo system consists of Energy Intelligent TS4 Module Level Power Electronics (MLPEs) that include a Rapid Shutdown (RSD) solution. These MLPE units are intelligent, functioning like small in-line computers that are connected to each photovoltaic (PV) module. It is essential to consider what factors can affect these electronics and whether traditional testing methods are suitable for them.

Testing Methods

Tigo TS4 Systems are separated into two families, with their testing methods:

Before testing, always refer to the following:

Know which MLPE family you are working with (and the proper testing methods that apply)
Follow all safety and operation instructions of the insulation tester you are using
Follow general electrical safety practices
Have a certified electrician perform the test
Make sure that all wires and conductors being tested are rated to the same voltage (or higher) than the test requires. (The voltage rating of the PV cables on Tigo products is printed on them.

Monitored Systems

Applicable Tigo MLPE:
All TS4-O or -S variants; Gateway, Cloud Connect, or Cloud Connect Advanced dataloggers

Tigo Smart / Optimizer MLPE units are sold in an open position (passing full voltage / no RSD response). Once commissioned, these systems require Radio Communications (from the Tigo Access Point-TAP) to stay energized and pass full module voltage.

The TS4 state (commissioned vs. not commissioned) dictates which conditions must be present for the MLPE units to pass voltage.

Non-Commissioned - For non-commissioned TS4 units, no special considerations need to be made before following the test methods in the left column of the table (above).
Commissioned - A fully commissioned system is defined as a system that has completed the Discovery phase at the end of the EI App commissioning process. The test methods listed above can be applied to discovered units, but with RSD considerations in mind. A CCA & TAP signal must be present for the MLPE Units to pass voltage to the string.

ATTENTION:
Tigo strongly recommends activating rapid shutdown / AC Loss both before and after the test. This will allow the installer to safely access the system and prepare the necessary conditions for testing. Once the installer is ready to proceed, the system should be re-energized (by deactivating RSD / AC Loss) so that the units can pass voltage and/or current during the testing period.

✅ Open Circuit Voltage Test (String or module Voc):
As long as the Tigo Smart/Optimizer system is active (not in RSD), it or the string can be DC Voltage tested for Voc results using standard methods.

✅ Safety Voltage:

As long as the Tigo Smart / Optimizer system is not active (in RSD), an MLPE Unit or string can be DC Voltage tested for Safety Voltage. Safety voltage is either 0V (Zero) or 0.6V x number of MLPE units in series, depending on the type of MLPE tested.

✅ Maximum Power Circuit Voltage Test (Vmp):
As long as the Tigo Smart / Optimizer system is active (not in RSD), an MLPE Unit or string can be DC Voltage tested for Vmp results using the standard methods.

✅ Operating Current (Imp):
As long as the Tigo Smart / Optimizer system is active (not in RSD), an MLPE or string can be DC Amperage tested for Imp results using the standard methods.

✅ Insulation (megger) Testing:
An MLPE or String can be insulation tested using the standard methods. Specifically:

Testing from (-) to GND is testing home run integrity.
Testing from (+) to GND is testing entire system integrity (same as without MLPE presence).

See here diagrams explaining how to measure and what is detected in each method:

❌ Short Circuit Current (Isc):

The Module (panel) can be tested, but the MLPE cannot. The monitored products have built-in Short-circuit protection. A short circuit condition puts the TS4 unit into RSD, and the test shows zero current.

❌ IV Curve Tracing:
IV Curve tracing is not possible for any Tigo devices (whether RSD is activated or not). The IV Curve test will effectively cause the unit to shut down.

Rapid Shutdown Only Systems

Applicable Tigo MLPE:
TS4-X-F, TS4-A-F/2F units; RSS Transmitter or RSS Transmitter with Pure Signal Technology

TS4-F systems require a constant PLC signal from the RSS Transmitter to remain in an active state (passing voltage / non-RSD). These systems must have a completed circuit in order for units to receive the signal and continue passing voltage.

Standard testing procedures like Voc, Isc, Insulation (megger), and IV Curve Tracing are not possible.

✅ Maximum Power Circuit Voltage Test (Vmp):
Vmp testing is possible since this condition requires the TS4s to be connected to a Charge Controller or Inverter. Since this is a completed circuit, the TS4s receive the PLC signal.

✅ Operating Current (Imp): Clamp Meter
Imp testing is possible since the Clamp Meter is clamped around a conductor of a completed circuit.

✅ Open Circuit Voltage Test (Voc)
Voc testing is possible when measured at the PV inverter or PV module string terminals using Y-connectors.

The inverter should be OFF so that it is not performing maximum power point tracking.
RSS Transmitter should be energized.
Measure using the following method with Y connectors.

✅ Insulation (megger) Testing:
An MLPE or String can be insulation tested using the standard methods. See details above.

❌ Short Circuit Current (Isc):

The Module (panel) can be tested, but the MLPE cannot. The PLC family of Fire Safety products has built-in Short-circuit protection. If a unit is placed in a short circuit condition, the unit or string automatically enters RSD, and the test shows zero current.

❌ IV Curve Tracing:

IV Curve tracing is not possible for any Tigo devices (whether RSD is activated or not). The IV Curve test will effectively cause the unit to shut down.