Solar Lattice

Symptom

Fallback operation after loss of control or meter signal

ID
symptom:control-fallback-operation
IRI
https://solarlattice.org/kb/symptom/control-fallback-operation
Status
active
Also known as
Communication with the System Manager failed, timeout in communication for active power limitation, fallback mode, LimByEPM, fallback level, reactive power setpoint timeout, failsafe, restricted function, Loss of Meter Communication, Fallback activated

Fallback operation happens when an inverter or plant controller loses its energy meter, its system manager or its external setpoint. Instead of following live control, it switches to a predefined behaviour. In monitoring data, output either holds flat at a set fallback power or at the last received values, or drops to zero when a failsafe shutdown is configured. Look for SMA event 8708 or a fallback activated status, a flashing red LED warning, or a Failsafe or LimByEPM message on Solis displays. Likely causes are a meter that has failed or lost power, a damaged or unplugged communication cable between the inverter and the system manager, or an external setpoint that is missing or invalid. If output stays limited while the meter communicates normally, check the failsafe and EPM settings. Solis advises turning both the external and internal EPM fail safe options off when they are not needed. Start by checking that the meter is powered, then inspect the network connection and cables to the controller, and confirm the meter settings. Normal operation resumes once communication has been back for the configured re-entry time.

<!-- review notes

Claims

observed_as

c1 verified · fact Flat output below available power

In fallback the inverter holds AC output at a configured fallback setpoint, or at the last received values, until the trigger has stayed clear for the re-entry time.

verified by: review-workflowverified on: 2026-10-24review note: support check: partial - Fallback setpoint hold and re-entry time are stated, but the passages say nothing about irradiance staying normal/rising or power staying flat regardless of irradiance; the 'last received values' option is also covered.

c2 verified · fact Zero inverter AC output

With failsafe ON, losing the meter or CT shuts generation down. Tesla systems curtail output to zero when the lost meter is needed by the active control function.

verified by: review-workflowverified on: 2026-10-24

c3 verified · fact Fallback event message proposed

Examples are SMA event 8708 (timeout in communication for active power limitation) and Inverter Manager status IDs 2055/2056 (fallback activated/completed).

verified by: review-workflowverified on: 2026-10-24

c4 drafted · lead Inverter fault code display

Solis displays show a Failsafe alarm when the CT or meter disconnects with failsafe ON, or a LimByEPM message when external power meter limiting is active.

review note: support check: partial - The Failsafe alarm on the LCD is stated and a LimByEPM message is mentioned, but the passages do not say it appears when external power meter limiting is active (only that it can occur when the setting is on).; review: partial - The Failsafe LCD alarm on CT/meter disconnect with failsafe ON is stated, but the passages only say LimByEPM can occur when the external power meter setting is on, not that it shows when meter limiting is active or that it…

c5 verified · fact Inverter fault indicator light

A flashing red LED pattern warns that communication with the System Manager failed and that the inverter is running with restricted function.

verified by: review-workflowverified on: 2026-10-24

c6 verified · fact Frozen meter readings proposed

After loss of meter communication, the reported meter values stay frozen at their last value.

verified by: review-workflowverified on: 2026-10-24

c7 drafted · lead Meter invalid alert proposed

A Meter Invalid alert is raised on loss of meter communication, out-of-bounds or unreasonable readings, or a PT/CT failure, and control elements are then disabled.

Referenced by

Data