Sizes a single-string PV array against its inverter: checks the string voltage window against the inverter's MPPT range and absolute maximum DC voltage across the site's full temperature range, checks array current against the inverter's MPPT current limit, and sizes both the DC array cable and AC grid-connection cable.
Standards followed
IEC 62548 (photovoltaic array design requirements)IEC 60364-7-712 (electrical installations — solar photovoltaic power supply systems)
What it can do
- Temperature-corrected string voltage window (cold-weather maximum Voc, hot-weather minimum Vmpp) checked against the inverter's MPPT range and absolute maximum DC voltage.
- String design current (Isc × 1.25 margin, per IEC 62548 §7) checked against the inverter's maximum DC input current.
- DC and AC cable sizing, reusing the same ampacity/derating/voltage-drop engine as the Cable Sizing calculator.
- DC:AC oversizing ratio with an over/undersizing note against the typical 1.0-1.3 accepted range.
- Advanced: multi-string array design — combined MPPT current across parallel strings and string-level overcurrent protection sizing.
Example problem
A 20-module string with 49.5V Voc, −0.29%/°C temperature coefficient, at a site ranging from 5°C to 65°C.
- Cold factor at 5°C (20°C below the 25°C STC reference) = 1 + 0.0029×20 ≈ 1.058.
- Maximum string voltage = 20 × 49.5 × 1.058 ≈ 1047.42V — checked against the inverter's max DC voltage.
- Hot factor at 65°C (40°C above reference) = 1 − 0.0029×40 ≈ 0.884.
- Minimum string Vmpp range = 20 × Vmpp × 0.884, checked against the inverter's MPPT minimum voltage.
- DC cable sizing iterates through standard sizes until both ampacity and the ~2% voltage-drop guideline are satisfied.
Cold factor 1.058 → Vmax 1047.42V, hot factor 0.884 → Vmpp range 733.72-878.14V, DC cable sizing selects 1.5mm² at 1.94% voltage drop (this particular default scenario intentionally fails the Vmax and MPPT window checks, since the module/inverter placeholder values weren't chosen as a mutually-consistent example).
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