Solar voltage rise calculator (AS/NZS 4777.1)

Voltage rise from the point of supply to the inverter a.c. terminals using AS/NZS 4777.1:2024 Table B.1 ampere-metres, checked against the 2 % limit in cl. 3.3.3.

AS/NZS 4777.1:2024 cl. 3.3.3 & Table B.1

A

Maximum design current (cl. 3.3.3).

m

Point of supply to inverter a.c. terminals.

Enter the current and route length to calculate.

How this is worked out

  • AS/NZS 4777.1:2024 Appendix B (informative) Table B.1 gives ampere-metres per 1 % voltage rise by copper conductor size: voltage rise % = (length × current) ÷ that figure.
  • The result is judged against cl. 3.3.3: the overall rise from the point of supply to the inverter a.c. terminals must not exceed 2 %.
  • Current is the inverter's maximum design current per cl. 3.3.3; length is the full route length of the run.
  • Table B.1 equals AS/NZS 3000 Table C.8 and applies within the limitations of AS/NZS 3008.1.1 cl 4.2 (cl. B.2.2). Sizes above 95 mm² are not tabulated.

Common questions

Why is the rise checked, not the drop?+

An inverter pushes current towards the grid, so the voltage at its terminals is higher than at the point of supply. Too much rise makes the inverter trip on over-voltage or curtail output.

What does 2 % mean in volts?+

4.6 V on a 230 V single-phase supply and 8 V on 400 V three-phase. The tool shows both the percentage and the volts.

Does this include the rise inside the switchboard?+

No. It covers the cable run you enter. Sub-mains and consumer mains between the switchboard and the point of supply add their own rise. Run them as separate calculations and add the percentages.

Recording this test?

Field Efficient records voltage rise on the AS/NZS 4777.1 commissioning card and judges it against cl. 3.3.3 as you capture the reading.

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Indicative only. Verify against the current edition of the standard before relying on a result for design, certification or a compliance decision. This tool is not a substitute for the standard or for a licensed electrician's judgement.