SA Power Networks inverters promise flexible solar exports

Households with solar in constrained parts of the electricity network stand to profit from new inverter technology.

SA Power Networks inverters capable of responding to signals from the grid are being deployed so customers can sell more of their excess solar power.

Led by SA Power Networks, a new ARENA-funded project will trial the technology with 600 Victorian and South Australian households in areas where the network is most constrained.

By allowing solar export limits to be automatically adjusted every five minutes based on signals sent by the distribution network, SA Power Networks inverters will remove the need for a 5kW cap on the amount of energy households can sell back to the grid.

SA Power Networks Mark Vincent said they have a target to double the amount of solar that can be accommodated by the network by 2025.

“We are looking at smart solutions, rather than expensive network capacity investment, to help make it happen,” Vincent said.

The $4.8 million project offers a way for network operators to manage flows of electricity back into the grid to avoid voltage fluctuations that can threaten stability – a growing challenge for a grid designed to carry energy in one direction.

Using inverters that allow flexible – or dynamic – exports will free up more export opportunities for solar households, albeit at varying levels depending on conditions in the grid.

Project partner AusNet Services will lead the Victorian trials, which is also supported by solar inverter manufacturers Fronius, SMA, and SolarEdge and energy management provider SwitchDin.

SA Power Networks Flexible Exports for Solar PV Trial project
Arial view of South Australian suburb.

Stretched to the limit

The capacity of the network to accommodate two-directional energy flows is a particular challenge in South Australia where rooftop solar is being installed at world-leading rates. The Climate Council’s most recent scorecard shows that 35 per cent of households have installed panels, making rooftop solar the largest source of generation in the state.

On a typical day solar supplies about approximately 10 per cent of all the electricity consumed in South Australia, but at times this has spiked to reach nearly two thirds of demand. SA Power Networks has previously warned of the risk of blackouts if supplies of electricity exceed the amount being used at a given time.

If no action is taken, there are fears the electricity system will become less equitable, with late solar adopters constrained and the costs of upgrading the network passed onto all energy users — whether they benefit from solar or not.

If successful, the project hopes to create a connection standard for dynamic export enabled solar inverters and introduce a new solar connection agreement for customers that could be adopted by any network across Australia.

ARENA CEO Darren Miller is optimistic that the trial will lead to energy from rooftop solar being better utilised.

“Currently less than 10 per cent of rooftop solar systems installed across Australia operate with smart control systems which means many people are limited by what they can export back into the grid. If the trial is successful, it should help more customers sell more of their energy into the market and benefit from cost savings on their energy bills,” he said.

Enabling more renewable energy

Tesla is currently working with the South Australian Government to trial another approach to the challenge, aiming to deploy 50,000 rooftop solar and battery systems in the world’s largest virtual power plant. Able to be controlled remotely, the batteries will soak up excess energy during sunny periods to be injected into the network to balance supplies and voltage.

ARENA recently announced funding to grow the virtual power plant by installing 3,000 solar and battery systems at social housing properties around Adelaide. As well as providing 15 MW of generation capacity and 40.5 MWh of storage, the project will provide cheaper energy for social housing tenants.

The project has been supported under ARENA’s focus on improving the integration of renewable energy into the electricity network. Without more storage and measures to manage the variability of wind and solar, there is risk that energy becomes less affordable and reliable as the transition to renewables advances.