Max Microinverters per AC Branch Circuit (NEC 705.60)
The most microinverters or AC modules on one AC branch circuit.
Example
You enter
- Branch OCPD (A) 20
- Microinverter max AC current (A) 1.21
You get
- Max microinverters per branch 13 units
- Continuous limit a 16
Checked against published worked examples from: Enphase Energy.
Details, formula, and sources
ScopeTheir 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 or tablecontinuous_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.
Source and editionNEC 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.
Free accessThe 80% continuous limit is public NEC (many jurisdictions post the adopted NEC); the unit's maximum continuous AC output current comes from its datasheet.
What governsEstimate. AHJ and licensed professional govern.
API field namesbranch_ocpd_a, unit_max_current_a, max_microinverters, continuous_limit_a
- 80% continuous combined continuous AC output <= 80% of branch OCPD (inverse of the 125% continuous rule)NEC 690.8(B) / 705.60 / 240.4
- Datasheet current use the unit's max continuous AC output current, not wattage / voltage; the datasheet governsmicroinverter datasheet