Solar String Fusing Calculator
South West Tech — do your strings need fuses, and what rating?
TRADE GUIDE — VERIFY AGAINST AS/NZS 5033 & DATASHEETBoth values are on the module datasheet. Strings on separate MPPT inputs don't combine — count only strings paralleled together.
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| Possible back-feed into a faulted string | — |
| Module reverse current limit | — |
| Fuse rating window (1.5–2.4 × Isc) | — |
| Suggested standard gPV fuse | — |
| Minimum string cable rating | — |
| Fuse voltage rating required | — |
Method: back-feed = (strings − 1) × 1.25 × Isc; fuses required where this exceeds the module's max series fuse rating. Fuse window per AS/NZS 5033: ≥1.5 × Isc, ≤2.4 × Isc and ≤ module max series fuse rating; fuse BOTH polarities with gPV (IEC 60269-6) fuses rated ≥ maximum PV array voltage. String cable must carry the fuse rating (or 1.25 × combined backfeed where unfused). Guide only — the installing electrician must verify against AS/NZS 5033 and the module datasheet. South West Tech — 0488 224 284.