How many strings can I put in parallel without string fuses?

Plain explanation

When strings are in parallel, a shaded or faulty string can take reverse current from the others. JinkoSolar's installation manual gives the maximum recommended number of parallel connections as N ≤ (fuse rating / Isc) + 1, using the maximum series fuse rating and the short-circuit current from the label or datasheet. For the JKM440N-54HL4R-B: 25 A / 13.80 A + 1 = 2.81, so at most 2 strings in parallel before string fuse protection is needed. The bypass diode is not over-current protection. Local electrical codes and the inverter manual still apply.

Steps from the source

1. Take the maximum series fuse rating and Isc from the datasheet
2. N ≤ fuse rating / Isc + 1, round down
3. Above that, fit string fuses sized per the module and local code

"the maximum recommended number of parallel connections is: N ≤ Fuse Rating / Isc + 1"

Word for word from the source.

Source

Where installers ask this

• Why does 2 strings of series parallel not require fuses but 3 strings does? (r/SolarDIY)
• reddit.com/r/solar/comments/lb0gbo/how_to_select_a_fuse_for_a_solar_string/

General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.