When the AC conductor between the inverter and the feed-in point is too small or too long, line resistance gets too high, so the inverter raises its output voltage to export its power. This can push the voltage measured at the inverter terminals above the permitted limit, and the inverter then disconnects or stops exporting power, which shows up as nuisance overvoltage or voltage out-of-range trips. High utility voltage and extra resistance at terminals, fuses and breakers make the problem worse. To confirm it, calculate the voltage rise for each wire section, then measure the voltage drop at rated operation and compare it with the voltage at the feed-in point. Fix it by sizing the AC conductor cross-section correctly, center-feeding long microinverter branches, and tightening or remaking poor terminal connections. If the grid voltage is chronically high, ask the utility about a transformer tap change or a different feed-in point. Change inverter grid limits only with the grid operator's permission.
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caused_byc1 drafted · lead Undersized component
AC conductor cross-section too small for the inverter output current, so line resistance is too high.
sec=1.1 h=3d4e798a2e94sec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071c2 drafted · lead Long AC cable run proposed
Distance from the inverter or microinverters to the point of common coupling adds resistance and voltage rise.
sec=1.2 h=375bb72cfcefsec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071c3 verified · fact High utility grid voltage proposed
Chronically high utility voltage leaves less margin for wiring voltage rise before trip limits are reached.
sec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071verified by: review-workflowverified on: 2026-10-24
c4 verified · fact Poor connector contact
Transition resistance at terminals and fuse elements, such as trapped insulation or loose breaker screws, adds to the voltage rise.
sec=h1 h=af4516340071verified by: review-workflowverified on: 2026-10-24
affectssec=h760 h=f38aeee9fa0esec=h679 h=f38aeee9fa0esec=h1 h=af4516340071sec=h1 h=af4516340071c7 drafted · lead Microinverter
sec=1.2 h=375bb72cfcefsec=1.1 h=3d4e798a2e94presents_asc8 drafted · lead Grid voltage out of range
Voltage sensed at the inverter terminals goes past the IEEE 1547 limits, which gives an AC voltage out-of-range condition.
sec=1.2 h=375bb72cfcefsec=1.3 h=19725e2aaa1dc9 drafted · lead Inverter shutdown
The inverter disconnects or stops exporting power (nuisance tripping) until the voltage returns to range, so energy is lost.
sec=1.2 h=375bb72cfcefsec=1.1 h=3d4e798a2e94sec=h1 h=af4516340071detected_byc10 verified · fact Voltage rise calculation proposed
Calculate the voltage rise or drop for each wire section at rated operation and check the total against the design limit.
sec=1.1 h=3d4e798a2e94sec=1.4.1 h=d2261a2268b4sec=h1 h=af4516340071verified by: review-workflowverified on: 2026-10-24
c11 drafted · lead Grid voltage measurement
Measure the voltage drop during rated operation. A utility data logger at the PCC can record service voltage.
sec=h1 h=af4516340071sec=1.3 h=19725e2aaa1dreview note: support check: partial - The passages say to calculate and/or measure voltage drop at rated operation and that a utility data logger at the PCC can record voltage, but they do not tie these to detecting undersized conductors.
mitigated_byc12 drafted · lead Conductor upsizing proposed
Size the AC conductor cross-section correctly. Going up one AWG size often costs little.
sec=h760 h=f38aeee9fa0esec=h679 h=f38aeee9fa0esec=1.1 h=3d4e798a2e94sec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071c13 drafted · lead Center-fed branch circuit proposed
Splitting a microinverter branch into two sub-branches on one OCPD reduces the voltage rise at the last microinverter.
sec=1.1 h=3d4e798a2e94sec=1.3 h=19725e2aaa1dc14 drafted · lead Wiring and terminal check
Fix trapped insulation, loose screw connections and poorly assembled AC connection points.
sec=h1 h=af4516340071review note: support check: partial - SMA says to optimize connection conditions, naming trapped insulation, loose screws and poorly assembled connection points as causes, but it does not explicitly say to fix them.; review: partial - SMA names trapped insulation, loose screws and poorly assembled AC connection points as transition resistances that also affect voltage rise and says connection conditions must be optimized, but it lists these as a separate cause from an undersized cross-section, so…
c15 drafted · lead Transformer tap adjustment
The utility can change the tap on the distribution transformer to give more voltage margin.
sec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071c16 drafted · lead Inverter parameter adjustment
Only with grid operator permission: the grid interface voltage limits can be changed, which may affect other loads.
sec=h1 h=af4516340071c17 drafted · lead Utility company consultation
The grid operator may adjust voltage, expand the grid or offer a different feed-in point.
sec=1.3 h=19725e2aaa1dsec=h1 h=af4516340071related_to c3