Troubleshooting
SMA Solar Technology AG
32
SB3300TLHC-IEN094121
Installation Guide
9 Troubleshooting
The Sunny Boy is a complex high-technology device. As a result, the possibilities for fixing faults on
site are limited to just a few items. Do not attempt to carry out repairs other than those described here.
Use the SMA Solar Technology 24-hour replacement service and repair service instead.
9.1 The red LED is continuously lit
If the red LED of the status display is continuously on during operation, there is either a ground fault
in the PV generator or at least one of the varistors for the overvoltage protection is defective.
9.1.1 Checking the PV Generator for Ground Fault
1. Disconnect the Sunny Boy from both the DC and AC connections, as described in section
7.1 ”Opening the Sunny Boy” (page 29).
2. Measure the voltages between the plus and minus pole of a string against the ground potential.
If voltage is found, there is a ground fault in the corresponding string.
The approximate position of the ground fault can be determined from the ratio of the measured
voltages between plus against ground potential and minus against ground potential.
Example:
The ground fault is between the second and third module in this case.
DANGER!
Risk of lethal electric shock!
In case of a ground fault, the PV generator may carry high voltages.
• Do not touch the frame of the PV generator.
• Wait until no voltage can be measured.
• Do not connect strings with ground faults to the Sunny Boy.
20 V
20 V
20 V
20 V
20 V
V = 40 V
1
V = 60 V
2
