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All CollectionsService FAQ: Troubleshooting FaultsOptimizer Related Faults
Fault code 128: Output current backfeed (optimizers)
Fault code 128: Output current backfeed (optimizers)

Applicable to devices with optimizers

Updated over a week ago

These faults apply to the following sungrow products:

  • SG30CX / SG33CX / SG40CX / SG50CX / SG110CX

  • SG2.0RS-S / SG2.5RS-S / SG3.0RS-S / SG3.0RS /SG3.6RS / SG4.0RS / SG5.0RS / SG6.0RS

  • SH3.0RS/SH3.6RS/SH4.0RS/SH5.0RS/SH6.0RS

In the event of Fault Code 128 being informed through the App, the following corrective measures shall be taken:

Output current backfeed (Code 128)

Fault Name

Output current backfeed (fault code: 128)

Fault Type

Fault

Fault Condition

The output current of the optimizer backfeeds

Troubleshooting steps and methods

1. If strings are connected in parallel, check whether the number of modules varies considerably between the two strings, or the module is severely shaded.

2. If the alarm persists, please contact Sungrow Customer Service.

keywords: 128, code 128


For further information, please download the user manual here.

This manual is intended for professional technicians who are responsible for installation, operation, maintenance and troubleshooting of inverters, and users who need to check inverter parameters. The inverter must only be installed by professional technicians.

The professional technician is required to meet the following requirements:

  • Know electronic, electrical wiring and mechanical expertise, and be familiar with electrical and mechanical schematics.

  • Have received professional training related to the installation, commissioning and troubleshooting of electrical equipment.

  • Be able to quickly respond to hazards or emergencies that occur during installation, commissioning and troubleshooting.

  • Be familiar with local standards and relevant safety regulations of electrical systems.

  • Read this manual thoroughly and understand the safety instructions related to operations.

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