Max Microinverters per AC Branch Circuit (NEC 705.60)
The most microinverters or AC modules on one AC branch circuit: their combined continuous output, as a continuous load, cannot exceed 80% of the branch overcurrent device (NEC 705.60 / 690.8(B) / 240.4), so N = floor(OCPD x 0.80 / unit max current). A 20 A branch with an Enphase IQ7+ at 1.21 A allows 13 microinverters; a 1.0 A unit allows 16, a higher-output unit fewer. Use the unit's MAXIMUM continuous AC output current from its datasheet, not the panel wattage over voltage, and size the branch conductors and the point-of-connection to the same 125% continuous rule. The microinverter datasheet, the AHJ, and the adopted NEC edition govern.
Formula and source
continuous_limit_a = branch_ocpd_a x 0.80; max_microinverters = floor(continuous_limit_a / unit_max_current_a); branch_load_a = max_microinverters x unit_max_current_a.
NEC 705.60 (interconnected sources), 690.8(B) (continuous current), and 240.4 (conductor / OCPD protection), by name; the microinverter datasheet and the adopted NEC edition govern.
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