Richard McIndoe used to run one of the country's major electricity retailers, Energy Australia.

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But even he was surprised by the power usage in his home.

Energy Australia former managing director Richard McIndoe was surprised when he investigated the voltage of his electricity supply.

"I was getting up once every three or four months to change light globes," he told 7.30.

"And this is what led me to look at voltage.

"I'm being force-fed more electricity than I need," he said.

After he realised the scale of the problem he started a company that specialises in filtering out extra voltage in homes and businesses.

7.30 visited his house in Melbourne on a day when the grid was delivering electricity at 254 volts — just above the allowable voltage limit.

"Based on the 254 volts I'm getting here, I'm roughly paying about $1,200 more for my electricity each year than I need to.

"We have a major issue with regulating voltage across Australia. And it's getting worse."

What is voltage?

Sorry, this video has expired What are volts and how can they contribute to higher power bills?

Voltage is essentially electrical pressure.

It is the force that sends electrical current from power stations, through transmission lines, to your home or business.

The nominal voltage for Australian households is 230 volts, but because voltage fluctuates all the time, electricity should be delivered within an allowable range of between 216 and 253 volts.

For households in much of Australia, electricity is supplied with voltage towards the top end of that range and even just above the 253-volt limit.

Depending on the appliances in your home, that can mean greater electricity consumption and bigger power bills.

"Most customers just are not aware of it, so nothing happens about it," electrician Dean Spicer told 7.30.

"Once an appliance reaches saturation, that excess energy just burns off as heat, which is just money down the drain."

But high-quality comprehensive data on the voltages supplied to households is not easy to come by.

Voltage to households running high

7.30 asked two companies to take a snapshot of electricity meters across most of Australia. Their findings give an indication of the scale of the issue.

The metering company Metropolis sampled 12,012 electricity meters four times a day from October 19 to 30, in all states and territories except the Northern Territory and Western Australia.

The readings taken at 1:00pm, when rooftop solar panels are boosting network voltage, 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.

The average minimum reading recorded by Metropolis was 241.6 volts.

A recent survey of 12,000 homes found the average minimum voltage was well above the nominal level. ( ABC News: Natasha Johnson )

Metropolis also reported that 1,642 meters were above the 253-volt limit during the trial period, while just six meters were below the 216-volt lower threshold.

In Victoria, 20.2 per cent of meters logged readings outside 216-253 volt allowable range, as did 19.3 per cent in South Australia and 12.0 per cent in New South Wales.

The German battery company Sonnen also contributed data from 825 meters it has access to, taking hourly readings over five days, and the findings were similar.

Most of the meters Sonnen surveyed were connected to rooftop solar systems.

Twenty-six per cent of those meters logged readings above the 253-volt upper limit over the trial period.

It can burn out appliances

Scientist Sean Elphick runs an annual audit of the quality of Australia's electricity.

The survey, which has been running since 2002, has consistently found that higher voltage on the network that supplies households is a major concern.

Sean Elphick in his testing laboratory. ( ABC News: Jerry Rickard )

He says running voltages at the high end is a legacy of the way the network was designed.

"The realistic fact of the technical operation of networks is that some consumers will have higher voltages than others, and that's really unavoidable from an engineering sense," Mr Elphick told 7.30.

He is also researching the effect of changes in voltage on electrical appliances, and says higher voltages can mean some appliances will use more electricity.

"In general it will reduce the life of appliances, but it's fairly uncertain to what degree and there is a little more research to be done in that area, I think," Mr Elphick said.

"The impact on electronic devices is still to be really quantified."

'A difficult balance'

Andrew Dillon of Energy Networks Australia. ( ABC News )

Energy Networks Australia, the peak body for Australia's poles and wires companies, said managing voltage on the grid was a difficult balancing act.

Spokesman Andrew Dillon said this was because the networks had to account for a drop in voltage as power is consumed by households along electricity lines.

"Many households do have voltages towards the upper end of the range, and the reason for that is to ensure that all households along the street are not falling below the bottom of the range," he told 7.30.

For some parts of the network, such as remote areas of the NT, Queensland, and WA, low voltage is more of a problem, because electricity has to travel great distances to homes.

Mr Dillon acknowledged that higher voltage can have an effect on power consumption and appliances, but said the impact was minimal.

"Sustained high voltages at very high levels are likely to have an impact on power bills [and] networks are doing everything they can to ensure that doesn't happen on a regular basis across the country," he said.

Mr Dillon said the rapid uptake of rooftop solar systems was a particular issue for the networks, because solar systems are supplying extra electricity to the grid, and boosting voltages.

"There are technologies we could adopt today, to be able to manage the voltage challenges we have from solar better than we are now," he said.

"The problem we have is we are not willing to pay billions of dollars further on the network … [we're] after a smart, cost-effective transition."

Some poles and wires companies are trialling voltage reduction on a large scale, and there is evidence that this could cut electricity consumption.

The results of a recent trial, by the Victorian network United Energy, showed that when voltage was reduced at 20 substations in and around Melbourne, every 1 per cent reduction in voltage saw, on average, an estimated 0.69 per cent reduction in demand for electricity.

But there is also research by the Queensland network Energex showing the scale of the problem the networks are facing.

When Energex reviewed almost 34,000 of the electrical transformers on its network in 2014, it found 76 per cent of the transformers were set too high, and were sending too much voltage through to households.

High volts could mean wasted solar

There is one area where high voltage is definitely causing headaches, and that is for people who have installed rooftop solar systems.

Pensioner Paul Ryan installed solar panels on his house in the Victorian town of Warragul more than a year ago, but for much of that time they have not been working.

The system often has to shut off to protect itself from high voltages coming in from the grid.

"It turned out to be a bit of a white elephant in a sense," Mr Ryan told 7.30.

"It cost me an arm and a leg to set up this system and it's not performing."

Solar systems can shut off when voltages are too high. ( ABC News: Briana Shepherd )

Rooftop solar systems are designed to operate at a few volts higher than the grid, so they can feed electricity back into the local network.

But with network voltage supplied to households already running at the high end, solar energy feeding into the grid can boost the volts even higher, and over the 253-volt limit — causing solar inverters to shut off.

With 1.8 million solar systems installed in Australian homes and businesses, a significant amount of renewable energy may simply be wasted.

Mr Ryan's energy provider has acknowledged voltage in his area is running too high, and it has promised to adjust the settings on his local transformer to reduce the voltage getting to his house.