Branch Circuit Capacity
Plan your AC branch circuits to meet the following limits* for maximum number of microinverters per
branch when protected with a 20-amp over-current protection device (OCPD). For most multiphase
installations, use a 3-pole 20A OCPD. If installing the IQ 7A, use a 3-pole 25A OCPD.
NOTE: *Limits may vary. Refer to local requirements to define the number of microinverters
per branch in your area
Utility Service Requirements
The Enphase Microinverters work with single-phase or three-phase service. Measure AC line voltage
at the electrical utility connection to confirm that it is within range:
Wire Lengths and Voltage Rise
When planning the system, you must select the appropriate AC conductor size to minimize voltage
rise. Select the correct wire size based on the distance from the beginning of the microinverter AC
branch circuit to the breaker in the load center. Enphase recommends a voltage rise total of less than
2% for the sections from the microinverter AC branch circuit to the breaker in the load center.
Enphase provides guidance about choosing wire size and maximum conductor lengths in the Voltage
Rise Technical Brief at enphase.com/support. Refer to this brief for voltage rise values in Enphase Q
Cables and on how to calculate voltage rise in other wire sections of the system.
Standard guidelines for voltage rise on feeder and AC branch circuit conductors might not be
sufficient for microinverter AC branch circuits that contain the maximum allowable microinverters. This
is due to high inherent voltage rise on the AC branch circuit.
Best practice: Center-feed the branch circuit to minimize voltage rise in a fully-populated
branch. This practice greatly reduces the voltage rise as compared with an end-fed
branch. To center-feed a branch, divide the circuit into two sub-branch circuits protected
by a single OCPD.
Lightning and Surge Suppression
Enphase Microinverters have integral surge protection, greater than most traditional inverters.
However, if the surge has sufficient energy, the protection built into the microinverter can be
exceeded, and the equipment can be damaged. For this reason, Enphase recommends that you
protect your system with a lightning and/or surge suppression device. In addition to having some level
of surge suppression, it is also important to have insurance that protects against lightning and
electrical surges.
NOTE: Protection against lightning and resulting voltage surge must be in accordance
with local standards.
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