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.