“Flexible exports” vital to the value of rooftop PV, and could help avoid the big solar button

One of the best ways to avoid using the Big Solar Button, while also ensuring consumers get the most out of their rooftop PV investment, is not yet available to most of the nation’s households, despite having been rolled out in South Australia with great success.

A new report by the Institute of Energy Economic and Financial Analysis (IEEFA) has found that the “sluggish” and “patchwork” use of flexible rooftop solar exports across Australia is costing a big chunk of new and existing solar households tens of millions of dollars in lost income.

According to the report’s author, Dr Gabrielle Kuiper, that figure could balloon to more than $200 million over the next three years as more solar systems are installed, unless decisive action is taken to ensure the fast, consistent implementation of flexible exports across the National Electricity Market (NEM).

Flexible exports, as the name suggests, use smart inverter software to provide much more flexibility over how a rooftop solar system operates, allowing exports to vary throughout the day in response to communication from the network operators.

In South Australia, where rooftop solar generation has on numerous occasions met all of the state’s demand, flexible exports have been being rolled out since 2023, giving households installing new systems the option to export up to 10kW – double the previous limit of 5 kW – in return for allowing the network to lower those export limits “periodically” to manage grid stability.

To do this, the state’s distribution company, SA Power Networks, has developed software to forecast the network’s hosting capacity 24 hours in advance, on a five-minute basis, to safely and dynamically manage solar inflows of up to 10kW per inverter.

Households installing solar that don’t want to take part in SA Power Networks’ Flexible Exports scheme can also choose that option, but are given a hard export limit of 1.5kW.

For most of the time, customers signed up for flexible exports can export the maximum amount that the network and their inverter can handle – up to 10kW per phase. But when there’s too much solar for the network to handle, exports will be automatically adjusted to match the network capacity.

So far, it’s been a great success – not least of all because it preserves self-consumption for customers, meaning that even if the grid goes into “solar shutdown” mode, system owners can still use their solar, they just can’t export any energy back to the grid.

This means less likelihood that AEMO will need to hit the dreaded Big Solar Button. And the evidence shows that, even in rooftop solar saturated South Australia, very little network directed curtailment is being used.

“SA Power Networks modelling shows flexible exports will likely be set below the doubled 10kW limit only 2% of the time or approximately 50 daylight hours per year,” Kuiper says.

“This is extraordinary, especially given about half of households already have rooftop solar installed in the SA Power Networks area, and at times rooftop solar supplies more than the state’s total electricity demand.”

Kuiper says the extra energy can be used to partially displace large generators in wholesale supply, support local networks, and to stabilise the grid, unlocking an estimated $A5.08 billion in net benefits for all consumers to 2042, according to a Deloitte cost-benefit analysis.

Outside of South Australia, however, she says the lack of uniform national regulations leaves equipment manufacturers and installers, and ultimately consumers, disadvantaged by the inconsistent, inefficient, slow or non-existent rollout of flexible exports.

IEEFA estimates that the delays to implementing flexible exports outside of South Australia has cost households installing new solar systems and those with existing 8-15kW solar systems a combined $35 million in 2023.

The report estimates that this cost will accumulate to $211 million over the next three years, and will grow further if the implementation of flexible exports is delayed beyond 2026.

“The implementation across six jurisdictions by 11 different distribution network service providers (DNSPs) is being planned or delivered using a variety of standards and devices,” Kuiper says.

“Unless there is a nationally consistent approach to communication and integration, meeting all requirements for all DNSPs will be a huge undertaking by industry.

“What does this mean for the consumer? It will push up the cost of doing business in Australia for manufacturers, which ultimately will make Australia less appealing with higher product and installation costs than any other global region.”

Kuiper says that to avoid this, basic requirements could be put in place to minimise the costs of compliance by inverter manufacturers. At the federal level, she wants energy minister Chris Bowen to lodge a rule change to look at options to manage minimum system load – including the fast implementation of flexible exports.

“It is in the interests of consumers that these be put in place as soon as possible, given that approximately 300,000 household solar systems are being installed annually and the financial benefits calculated above,” Kuiper says.