Plain explanation
Inverter makers list 'too many modules in series' as a direct cause of DC overvoltage alarms: Huawei's alarm 2001 String Voltage High, GoodWe's fault 31 PV Input Overvoltage. Module open-circuit voltage goes up as the cells get colder, so a string that is fine in summer can go over the limit on a cold, bright morning. Work it out from the module datasheet (Voc and its temperature coefficient), the lowest expected site temperature and the inverter datasheet's maximum input voltage. The design temperature and the calculation method are set by local rules, so check your national code.
Steps from the source
- Take Voc and the Voc temperature coefficient from the module datasheet
- Use the lowest expected cell temperature for the site (per your national code)
- Multiply the corrected Voc by the number of modules in series
- Keep the result below the inverter's maximum DC input voltage (inverter datasheet)
"The PV array is not properly configured. Excessive PV modules are connected in series in the PV string, and therefore the PV string open-circuit voltage exceeds the maximum operating voltage of the device."
Word for word from the source.
Source
Where installers ask this
- Cold weather overvoltage (r/SolarUK)
- reddit.com/r/solar/comments/91o1hx/check_my_math_how_many_panels_can_i_have_in_a/
General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.