Yesterday was a mild, sunny day in Adelaide with huge amounts of solar energy being pumped onto the grid. So much so that it appears that SAPN has demonstrated its flexible export restrictions.
What are flexible exports?
The uptake of residential solar energy in South Australia has been phenomenal. More than 411,000 systems were installed in the state, which only has around 1.8 million inhabitants. The electricity generated by these plants, which is fed into the grid, helps reduce wholesale electricity prices. But sometimes you can have too much of a good thing, and that will become more and more the case as the years go by. A very high proportion of solar in the grid and too little demand can lead to grid instability and power outages.
One of the tools SA Power Networks (SAPN) has to manage rooftop solar installations is flexible (aka dynamic) exports. Systems can adapt to network conditions using signals that SAPN sends remotely to compatible inverters. This allows for a much higher maximum export limit (up to 10kW instead of 5kW) for much of the time. However, it can be reduced to up to 1.5kW if the grid is overloaded with solar energy, demand is comparatively low and the excess cannot be exported to Victoria for some reason.
Trevor from SQ experiences his first limitation
SA Power Networks (SAPN) began making a flexible export option available to more solar homes through a phased rollout last July, and in July this year announced that owners of compatible systems at more than 200 additional locations across the state will be able to participate .
SolarQuotes General Manager Trevor decided to sign up before the virtual ink could dry on the announcement. He is a brave man because once you change, there is no going back. It has 20kW solar panels, a 10kW inverter, a home battery and a couple of electric cars. On July 24, it switched from its fixed export limit of 5 kW to flexible exports.
Trevor didn’t get much, other than being able to export more, which he was very happy about. That was until yesterday. His system had exported about 9 kW over the course of the morning:
… but before midday this decline began and fell to as low as 5 kW, even though the weather conditions were perfect for solar power generation – clear skies and around 16°C.
Looking at Open Electricity (formerly OpenNEM), rooftop solar alone covered almost 81% of South Australia’s electricity needs as of midday.
But that’s not all: at 1:30 p.m., the rooftop solar array was covering 88.1% of demand, which was pretty impressive considering it was a weekday. At this point, renewable energy across the state met 123.9% of South Africa’s electricity needs.
Trevor’s exports remained at around 5kW for a while and then gradually increased again (with a few brief dips) until around 2pm. Thereafter, there was another decline, with rooftop solar alone covering 83% of demand before increasing again – and then system generation began to decline. This is what the day looked like until around 4:20 p.m.:
So this was Trevor’s first experience with flexible export reduction. It is a much more elegant solution for managing solar power systems than another (dull) SAPN stopgap tool, namely remote disconnect/reconnect. As far as I know, this has rarely been used before and flexible exports will help reduce the cases where SAPN may need to use that big red button. And other states will follow in SAPN’s footsteps.
Note that by the end of 2024, all new solar installations or upgraded systems that involve an inverter replacement will be subject to the choice of flexible exports or a fixed limit of just 1.5kW across South Australia. But existing solar owners who already have a 5kW export limit can keep it if they wish.
Further information about SAPN’s flexible export initiative can be found here.
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