Definition
String voltage is the sum of voltages across series-connected PV modules. Cold-day Voc must stay below NEC 690.7 limits and inverter MPPT max. Hot-day Vmp must stay above inverter MPPT min.
Key Takeaways
- String voltage = N × module voltage.
- Cold Voc bound: NEC 690.7 + inverter MPPT max.
- Hot Vmp bound: inverter MPPT min.
- Always temperature-correct using ASHRAE extreme min/max.
- Document on SLD with calculation.
Frequently Asked Questions
3 commonly searched questions about String Voltage.
What is string voltage?
Sum of voltages of series-connected PV modules. Voc(string) = N × Voc(module). Vmp(string) = N × Vmp(module).
What's the limit?
NEC 690.7: 1000 V commercial, 600 V residential, 1500 V utility. Inverter MPPT range further constrains.
Temperature effect?
Cold raises Voc; hot lowers Vmp. Always temperature-correct using site-specific extremes.
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