Definition
Stringing is the process of wiring PV modules in series to form strings of suitable voltage and current for the inverter MPPT. Encompasses layout planning, MC4 connector terminations, conductor routing, and per-MPPT current balancing.
Best Practices
- Minimize wire length between modules and the combiner/inverter.
- Use same-length strings on each MPPT for best mismatch performance.
- Reserve dedicated MPPTs for different orientations, tilts, or shading profiles.
- Label every string at the combiner/inverter input.
- Document per-MPPT current and voltage in the SLD.
Key Takeaways
- Stringing = wiring PV modules in series within string-sizing constraints.
- Auto-stringing in Helioscope, Aurora, and manufacturer tools respects MPPT limits.
- Mix string lengths only within per-MPPT current capacity.
- Use separate MPPTs for distinct orientations or shading profiles.
- Label every string for commissioning and maintenance.
Frequently Asked Questions
5 commonly searched questions about Stringing.
What is stringing?
The physical wiring of PV modules in series to form strings for the inverter input. Includes layout, MC4 connector terminations, conductor routing, and per-MPPT balancing.
How is stringing decided?
By string sizing calculation (NEC 690.7 cold Voc + MPPT min hot Vmp), then by layout — minimize wire length, balance per-MPPT current, avoid crossing conductors.
What software auto-strings?
Helioscope auto-stringing respects MPPT voltage and current limits. Aurora auto-fills residential strings. Manufacturer tools (SMA Sunny Design, Sungrow) optimize for their specific inverters.
Can I mix strings on a single MPPT?
Same length yes; different lengths only within per-string current limits. Different orientations/tilts → use separate MPPTs (4–8% mismatch loss otherwise).
Where are strings combined?
At the inverter inputs (string inverters with multiple MPPTs) or in a combiner box (commercial/utility plants with shared MPPT).
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