Abnormal external conditions trigger the protection for the DC circuit inside the SUN2000. The possible causes are as follows:
| Possible Cause | Suggestions |
| Cause ID 3: Major The SUN2000 input is disconnected accidentally, or the PV string output power changes sharply because the PV string is shielded from sunlight. |  |
| Cause ID 10: Major The three phases of the power grid are seriously unbalanced, which triggers the protection for the internal control circuit of the SUN2000. |  |
| Cause ID 11: Major The grid voltage changes sharply and the SUN2000 input power fails to discharge in a short time, which increases the internal voltage and triggers overvoltage protection. |  |
| Cause ID 12/15: Major An unrecoverable fault occurs on a circuit inside the SUN2000. | |