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Rooftop solar threat to grid requires holistic response


Preventing South Australian summer blackouts requires a whole government solution and can’t be solved by switching off rooftop solar alone, according to a state energy expert.

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The State Government and Opposition have been at loggerheads in recent weeks over a plan to allow the Australian Energy Market Operator (AEMO) the capacity to turn off household rooftop solar to prevent summer blackouts when too much surplus solar is in the market.

It comes as SA Power Networks last week announced it would upgrade voltage management systems at about 140 of its major substations to cope with more solar power being pumped into the grid.

While the upgrade is designed to ease potential pressure in the system, it also aims to cater for increased solar output as more households install panels.

UniSA research fellow Stephen Berry told InDaily while the State power network’s move to upgrade was “an appropriate response” it did not solve South Australia’s underlying energy issue.

He said it, along with the move to grant the Australian Energy Market Operator (AEMO) capacity to turn off household rooftop solar to prevent summer blackouts, were “band-aid” solutions to a much larger national issue.

“What we’ve done is move from one organisation – being the Government being totally responsible for the complete system for providing electricity – to a situation where there are lots of different parts,” Berry said.

“What that means is that each one is coming up with a solution for what they can do for their business, not what is best for the entire system and that works perfectly well for their shareholders and for their business. But it might not be the best overall solution or sets of solutions, because each one is doing their own thing.

“What we need to have is genuine, holistic policy where all of the parties are working together for what is the best solution set for the whole infrastructure not just for their individual companies.”

He said while it may be necessary for AEMO to turn off South Australian household solar for up to a few hours when there was an “imbalance between supply and demand” ultimately grid instability depended on long-term federal planning.

“AEMO can’t, to a degree, control how many people put PV on their rooftop or how many new solar farms or wind turbines are built,” he said.

“They can’t control the supply, yet they have to balance supply and demand. They’re looking at what they can do to fix the problem that they have in delivering a quality of electricity.

“What we need to do is have a stronger role by government in understanding how the whole system works and getting the parties to work together. The federal level needs to pull all of the parties together to provide that infrastructure and investment to provide the whole system solutions rather than everybody put a band-aid on what they see as the sore point.

“This is about a restructure of the whole electricity network, so we can capture the wonderful benefits of when there is free supply, or free sunlight and free wind, when we can capture that but use it in a productive way.”

SA Power Networks last week announced the state’s electricity network was undergoing upgrades to handle more solar power being pumped into the grid.

A statement from the network said it would upgrade voltage management systems at about 140 major substations supporting about 790,000 of South Australia’s 900,000 electricity customers.

It said South Australia had more than 270,000 customers with solar systems capable of generating about 1500MW of energy, equal to several large coal or gas-fired power stations.

SA Power Networks’ manager of corporate affairs Paul Roberts said the network had to move quickly to balance support for the fast-growing number of solar customers, AEMO and the State Government.

“SA Power Networks, with welcome support from the State Government, is investing in the rapid deployment of new voltage control measures in our larger substations,” Roberts said.

“This will help us better regulate voltage levels throughout the day and year.

“So, during those periods of high solar export in the middle of the day, we can keep the volts down to ensure customers can continue to export their excess power to the grid.”

SA Power Network said its voltage management upgrades had already been implemented at 40 sites, with the remaining 100 planned to be completed by early 2021.

It said the upgrades would allow it to better deal with load and supply issues should the State’s interconnector to Victoria go down.

It followed the State Government and Opposition trading blows over a proposal to allow South Australian Power Networks to stop household solar power feeding back into the grid.

Last month, AEMO released its electricity forecast – the Electricity Statement of Opportunities – which highlighted a need to be able to switch off rooftop solar remotely as well as for individual existing customers.

AEMO said it did not expect to need to have to disconnect existing solar after the coming summer and anticipated grid reliability would improve in the coming decade.

The State Government has said it would allow SA Power Networks to manage power going into the grid from household solar panels.

“AEMO’s role is to maintain the security of the power system and they have indicated that they may need to manage the output of rooftop solar systems for short periods of time to prevent blackouts. This would be as a last resort measure, which hopefully will not need to be utilised,” a spokesperson said.

“AEMO has recommended this as the best means of avoiding the costly and disruptive effects of widespread blackouts.”

The State Government says the policy is critical to grid stability and will cost households with solar systems only “a few dollars per year if needed”.

Opposition energy spokesman Tom Koutsantonis said the proposal would impact properties with battery backup.

“What they are going to inadvertently do by forcing this is make batteries … obsolete during a blackout,” he said.

“They are also going to have a requirement on customers to have an agent in place to monitor their solar panels and to act as the agent to turn their solar power off when required by the government.

“That means that that cost be borne by the householder and we don’t know how much that is going to cost.”

He said the solar industry had also been told that there would be a ban on new installations unless the power management changes were implemented.

On Friday, Australia’s Renewable Energy Agency (ARENA) announced $8.2 million in funding to Tesla Motors Australia to install residential battery and rooftop solar systems at 3000 properties owned by Housing SA across Adelaide.

The housing trust tenants will then join in Australia’s largest virtual power plant, which aims to deliver lower energy bills and a more resilient electricity grid. Tesla will install 5 kW of rooftop solar and a 13.5 kWh Powerwall battery system at each property, at no cost to the tenant. The system will provide approximately 80 per cent of average household energy use.

Together with 1100 systems already installed in a previous phase, the combined 20 MW / 54 MWh of residential energy storage will be used by Tesla in a centrally controlled VPP trial.

Housing SA tenants involved in the trial, like other renters, are usually locked out of being able to benefit from renewable energy. The tenants will benefit from cheaper household electricity bills, with the project offering electricity rates 22 per cent lower than the default market offer.

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