FailureMode
Rapid shutdown PLC signal crosstalk
- ID
fm:plc-signal-crosstalk- IRI
https://solarlattice.org/kb/fm/plc-signal-crosstalk- Status
- active
- Also known as
- PLC crosstalk, signal crosstalk on PV conductors, multiple transmitter interference, Crosstalk
Crosstalk happens when a power line communication signal from one rapid shutdown transmitter is induced onto DC conductors that belong to another transmitter. It shows up on sites with several transmitters, often built into parallel inverters, where DC conductors from different transmitters are bundled or run close together. Module-level receivers then shut down even though no shutdown was commanded. This causes lost output, low production, inverter shutdowns and repeated arc-fault alarms. If the crosstalk is severe, receivers can overheat, and both transmitters and receivers can be damaged. On sites with several transmitters, test the rapid shutdown system during commissioning and watch inverter performance for several days afterward. The best fix is a single transmitter for the whole site. Otherwise, split the array into separated blocks, each with its own inverters, DC wiring and transmitter. Keep wiring for different transmitters well apart, keep shared runs short, and route each homerun's positive and negative conductors together with a light twist.
<!-- review notes
- sentence 3: support check: partial - Unintended receiver shutdown and lost output/low production are stated; inverter shutdowns and arc-fault alarms are listed as costs but not explicitly as crosstalk effects.
- sentence 4: support check: partial - Severe crosstalk can overheat receivers is stated; damage to transmitters and receivers is mentioned but not explicitly conditioned on severity.
- sentence 4: review: partial - Severe crosstalk causing receivers to overheat is stated, but damage to transmitters and receivers appears only as a possible cost and is not tied to severity.
-->
Claims
caused_by
c1 drafted · lead
Multiple PLC signal transmitters proposed
Several rapid shutdown transmitters, for example ones built into parallel string inverters, operating on one roof or site.
c2 drafted · lead
Close DC conductor proximity proposed
DC conductors tied to different transmitters are bundled or run close together. The signal couples more easily between conductors of the same polarity, even through insulation or separate metallic tubing.
affects
c3 drafted · lead
Module-level rapid shutdown device
Module-level receivers malfunction, shut down unexpectedly and can overheat.
c4 drafted · lead
Rapid shutdown signal transmitter
review note: support check: partial - Transmitters can be damaged by crosstalk (u3), but the passages mainly describe the transmitter as the source; damage is only mentioned loosely as a cost-avoidance consequence.
c5 drafted · lead
DC cable
The PLC signal travels on the PV array DC conductors.
presents_as
c6 drafted · lead
Rapid shutdown triggered
Receivers shut down even though the transmitter was never turned off.
c7 drafted · lead
Low output despite irradiance
Loss of PV system output or low production.
c8 drafted · lead
Arc fault detected
Repeated arc-fault alarms at the inverter.
review note: support check: partial - Ongoing arc-fault alarms at the inverter are mentioned as costs of crosstalk, but only indirectly and without stating they are caused by it; 'repeated' is implied by 'ongoing'.
c9 drafted · lead
Inverter shutdown
review note: support check: partial - Inverter shutdowns are listed among problems to be avoided, but it is not clearly stated as a crosstalk symptom.
leads_to
c10 drafted · lead
Rapid shutdown device failure
Severe crosstalk can overheat receivers and damage both transmitters and receivers.
review note: support check: partial - Overheating of receivers under severe crosstalk is stated, and damage to transmitters and receivers is mentioned, though the damage is not explicitly tied to severe crosstalk.
detected_by
c11 drafted · lead
Rapid shutdown function test proposed
Required at commissioning on sites with several transmitters whose DC wiring runs close together.
c12 drafted · lead
Performance monitoring
Watch inverter performance for several days after installation.
mitigated_by
c13 verified · fact
PLC transmitter consolidation and conductor separation
Disable the transmitters built into the inverters and use one external transmitter, or split the array into separated blocks that each have their own transmitter, for example along fire access pathways.
verified by: review-workflowverified on: 2026-10-24
c14 drafted · lead
Proper cable routing
Keep the bundles, conduit and tray of different transmitters apart. Keep PLC loops short. Keep shared runs as short as possible.
c15 verified · fact
Paired homerun conductor routing proposed
Run the positive and negative conductors of a homerun together and twist them lightly.
verified by: review-workflowverified on: 2026-10-24
Referenced by
Data