When engineer Rolf Wittwer retired in 2012, his dream project was designing an energy-efficient home near the town of Port Broughton in South Australia.
- More than 2 million Australian households have rooftop solar systems
- When solar systems feed extra energy into the grid, it can increase voltages on nearby power lines
- A UNSW study found voltages were already sometimes over the upper limit of what was allowed
Rooftop solar was a big part of his plan because he wanted to save money on his energy bills by feeding energy back into the grid.
But things didn’t go as planned.
“I was looking to see my return on investment flowing in and I was horrified to see that [the solar system] was constantly shutting down and restarting — up to 13 times a day,” he said.
He suspected the voltage on the powerlines near his house was running too high, so when his rooftop system fed in spare energy it was enough to drive the voltage on nearby powerlines over the permitted limit.
That meant his solar system shut down automatically.
Mr Wittwer’s network provider, South Australia Power Networks, told the ABC it checked the voltage near his house in August 2017 after the solar system was first installed, and it was operating within the allowable range of between 216 and 253 volts.
Mr Wittwer got his system rewired and last year added extra panels and an expensive battery. But his solar system can still only export a fraction of the energy it produces.
He’s still convinced the voltage on his local network is running too high.
UNSW research finds high voltage widespread
Mr Wittwer’s is one of more than 2 million Australian households with a rooftop solar system.
As take-up of this renewable energy has grown, it’s been blamed for destabilising the grid, in part because it can potentially increase voltages on nearby electricity lines.
But a University of New South Wales (UNSW) study has shown voltages are already close to, and sometimes over the upper limit, of what’s allowed — and rooftop solar has little impact.
Based on the data, the Energy Security Board has suggested the energy networks could be breaching technical voltage regulations.
Voltage is the force that moves electrical current through powerlines to homes.
It is controlled through a series of transformers, which reduce the voltage of the electricity running through powerlines from the high-voltage transmission network to the lower-voltage distribution network near people’s homes.
If voltage is too low, the power will be poor quality and may even cut out.
If it’s too high, energy will be wasted, power bills may increase, and some appliances may burn out faster.
For its study, UNSW crunched the data of more than 12,000 solar households, analysing the voltage of the electricity reaching the homes before any extra solar power could affect the readings.
Even though the nominal voltage on the grid is 230 volts, the researchers found 95 per cent of readings were higher than that level.
When voltage levels are near or even above 253 volts, there’s already no room for households wanting to feed even the smallest amount of solar energy back into the grid.
What’s going on in the grid?
The Energy Security Board, which commissioned the UNSW study, said the findings pointed to a “material level of technical non-compliance” by the networks, and a “backlog of compliance issues” that needed work.
The peak body for the poles and wires companies, Energy Networks Australia (ENA), said in most Australian states, network companies themselves had very limited information about voltages near people’s homes.
“We need more information. This is the challenge — knowing what is going on in the grid,” Andrew Dillon, chief executive of ENA, said.
But Mr Dillon promised the networks were looking for cost-effective solutions to high voltages that would not drive up power bills.
“There are simple measures we can take to start to remedy this and they are all underway pretty much everywhere,” he said.
Advocates of renewable energy said more investigation, especially into background voltage levels set by networks, was needed.
“This report is really important because it encourages us to actually have a look at all the factors that are leading to high voltage in the grid, and not just pointing the finger at rooftop solar,” said Ellen Roberts, the national director of Solar Citizens.
She said she feared solar, which was often blamed for grid instability, had become an easy scapegoat.
“Rooftop solar has really driven down power prices and been a source of clean renewable energy for all, which has meant that it’s dinted the profits of some of those big coal and gas generators,” she said.
For the past eight years, electrician Peter Sutrin has run his own solar business in the Queensland city of Toowoomba, on the Darling Downs.
He said voltage issues existed in the network long before solar grew popular.
“It’s easy just to blame what wasn’t there before, but the fact is the problem was always there and now people are just finding out about it,” he said.
“I will say I think the network has a very difficult job, a very large job, in trying to balance the voltages across Queensland. I will give them that.
“But at the same time, I’m not really sure if they are doing very much about it, they’re not letting anyone know too much.”
Voltage difficult to monitor, regulator says
The ABC approached regulators in Queensland, New South Wales, the ACT, Victoria, South Australia and Tasmania — the states and territories which make up the National Electricity Market — and asked how non-compliance on the low-voltage distribution network was dealt with.
None could provide the ABC with an example of when, or if, such action had been taken.
The potential fines for voltage non-compliance could add up to millions of dollars.
In a written statement, a spokesman for South Australia’s Department for Energy and Mining said compliance was difficult to monitor due to limited visibility.
“Voltage complaints are investigated and, if necessary, data loggers would be installed to assess the issue,” he said.
“If required, the network operator would then take action to balance the load on the network. Distributors, including SA Power Networks, are working on implementing solutions to address this issue”.
Watch the full story on 7.30 tonight on ABC TV.