Event number 4002
Event number 4002 indicates that the activated string-failure detection has detected a failed or weak string. This is only a warning message, the Sunny Tripower does not beep and continues feeding in power with the unaffected strings.
Background information:
The 8/10/12/15/17000TL-10 Sunny Tripower (STP) inverters possess a self-learning string failure detection, which is responsible for checking string inputs A and B. This detects the failure of an individual string or substring. If an error occurs in the string, string-failure detection disconnects the affected input from the inverter. This avoids having to shut down the entire PV array. In order for the string-failure detection to be reliable, identically aligned PV modules must be connected to both inputs of the inverter. Please note that extreme shading and snow-covered PV modules also lead to warning messages.
String-failure detection has been deactivated by default in all STPx000TL-10 devices that have been delivered since April 6, 2011. It can be activated on request (if all requirements for this have been met). String-failure detection was active in all devices prior to April 6, 2011. The Sunny Tripower needs around 14 days after activation for the learning phase with moderate irradiation (at least 5 hours a day).
For the smooth functioning of string-failure detection, the following requirements apply:
For the strings connected at input A:
• Same module type
• Same number of PV modules per string
• Identical alignment of all strings
• Identical inclination of all strings
For input area B, only the following applies:
• Identical alignment
• Identical inclination of the modules with input area A
• The number of modules in the string as well as the module type do not have to be identical with input area A.
If these requirements have not been met, you can deactivate string-failure detection by setting a parameter (e.g. in the Sunny Explorer under Settings / DC side / String-failure detection), as described in the operating manual. After string-failure detection has been deactivated, event number 4002 is no longer displayed.
Corrective measures for system operators:
• If possible without danger: Check whether the modules are soiled or shaded
• Use the design data to check whether all above-mentioned requirements for activated string failure detection have been met.
• Contact an installer or an SMA solar power professional. The subsequent steps require the specialist knowledge of an electrically qualified person or installer.
Corrective measures for installers:
DANGER! The tasks described below may only be performed by electrically qualified persons:
• Check whether all above-mentioned requirements for activated string failure detection have been met. If not, deactivate string-failure detection, as described in the operating manual.
• Test the string that is shown in the message:
o Measure the open-circuit voltages of all strings when the irradiation is sufficient.
o Measure the short-circuit currents of all strings. A suitable measuring device and a suitable device for safe disconnection and short-circuiting of the strings is required for this.
o Compare the measurement data with the information on the module data sheet (taking the irradiation values / weather into consideration)
All work on the inverter and the cabling of the PV array must be carried out by an electrically qualified person. SMA accepts no liability for the information and solutions given in the Online Service Center. Additional information can be found in our Online Service Center’s terms and conditions of use.