Our analysis of power line voltages across the National Electricity Grid highlights significant variation.

Metropolis sampled over 12,000 electricity smart meters four times a day across all states and territories except the Northern Territory and Western Australia.

Voltage readings taken during the day, when rooftop solar is active, averaged 245.8 volts, within allowable limits, but well above the 230 nominal level.

But even at night, when extra voltage from solar power is not a factor, the network voltage is still running high, impacting household power bills.

As reported by the ABC 7:30 Report many homes supplied at the higher end of the regulated range causes appliances to draw extra power resulting in higher electricity bills.