Table 1: Allowable limit for distribution transformer (DT) loading, voltage regulation, and harmonics [11, 12].

AttributesRecommended limitRegulatory standard

DT loading80% of the installed capacity, withstand up to 120%
Inverter capacity10 kVA for single phase
30 kVA for three phase
AS 4777 [11]
Voltage regulationAllowable limit is 6%, that is, 240 V 6% for single phase and 415 V 6% for three-phase systems
Voltage rise due to PV at PCC is 1% at 240 V line to neutral voltage.
AS 4777 [11]
HarmonicsTHD up to 50th harmonic should be less than 5%
voltage harmonic limit to 8%.
AS 4777 [11]