Solar PV Code Comparison
The distinction between string-level and combined-current circuits shows up under every code, not just the NEC.
The NEC Article 690 article in this series introduced the distinction between PV source circuits (string-level current) and PV output circuits (combined current at a combiner point). The underlying concept isn't NEC-specific terminology — it applies under PEC and AS/NZS just as much, even where the exact naming differs.
Any conductor downstream of a point where multiple parallel strings combine needs to be sized for the combined current of everything feeding into it — never for a single string's current, regardless of which code's terminology you're using to describe the circuit.
It's one of the most common real-world PV cable sizing mistakes precisely because it's easy to mentally "reuse" the per-string current figure at every downstream point without re-deriving the actual combined current — see the dedicated combiner box article for the specific worked-through mechanics.
At every point in a PV array's wiring where current combines — string to combiner, combiner to sub-combiner, sub-combiner to inverter — stop and recalculate the actual design current explicitly, rather than assuming a previously-calculated figure still applies.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks