Solar Cable Sizing
The inverter-to-switchboard AC run has its own specific sizing considerations, distinct from the DC side entirely.
The AC cable running from a solar inverter's output to the main switchboard is a genuinely different sizing exercise from the DC array cabling covered throughout most of this series — different current basis, different voltage drop limit, different protective device coordination.
Rather than being driven by module Isc, AC output cable sizing starts from the inverter's rated continuous AC output current — typically with the same kind of continuous-load safety margin applied as any other sustained-output circuit.
General AC circuit voltage drop limits apply here (commonly 3–5% depending on code) — meaningfully looser than the tighter 1–3% typically applied to DC array circuits, since the AC side doesn't compound the same way across 25 years of daily production the way DC string losses do.
The AC output circuit breaker at the switchboard needs to be correctly rated against the inverter's actual output current with its own applicable safety margin — undersizing this breaker causes nuisance tripping during normal inverter startup transients; oversizing it fails to protect the AC cable itself.
Size your inverter's AC output run in the applicable code's Cable Sizing calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks