Rooftop solar pushes South Australia to record low demand (again)

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Rooftop solar – along with sunny weather and mild temperatures – push grid demand in South Australia to yet another record low.

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The combination of growing rooftop solar installations, mild temperatures and sunny weather has pushed South Australia’s grid demand to yet another record low, this time shaving around 6 per cent off the previous low set just six weeks ago.

The new low was set just before 1.30pm in South Australia (just before 2pm on National Electricity Market time) when the minimum grid demand hit 554MW.

This shaved some 33MW off the previous low of 587MW set on September 17,which itself was nearly 200MW or 25 per cent the previous record low demand of 786MW set just a week earlier.


SA rooftop solar - demand -
Graph: Dylan McConnell from Climate and Energy College in Melbourne.

For six hours, according to the APVI solar map, rooftop solar PV provided more than 30 per cent of the state’s demand. For nearly three hours, rooftop solar provided more than 40 per cent of the state’s demand.

As we explore in this article here, rooftop solar provided 9.2 per cent of the state’s local generation in 2016/17 and would likely be more than 10 per cent if larger rooftop solar installations were included.

Within a decade, that share is expected to double to more than 20 per cent, at which times on days like this Sunday, minimum demand may actually fall to zero because of the amount of solar being generated.

SA low demand graph -

The Australian Energy Market Operator, which includes these forecasts in a new report into the South Australia grid, suggests that by that time it will be necessary to store some of that excess solar for use later in the day.

The same situation may occur in West Australia, too, because of the amount of rooftop solar being installed in a small grid. The uptake of rooftop solar is accelerating because of high grid prices and the falling cost of solar technology, and grid demand fell in W.A. to an 8-year low last week.

“At these times, South Australia could store or export its excess generation to the rest of the NEM via the interconnectors, provided they are in service,” AEMO notes in its report.

“This, in turn, will provide market participants with greater opportunity to manage their energy use.”

AEMO noted, as it has previously, that South Australia is the first region in the NEM in which high rooftop PV penetration has caused minimum demand to shift from overnight to near midday – a transition that occurred five years ago.

Many argue this is a good reason to shift the “controlled load” of electric hot water systems from the night-time to the mid-day hours, particularly since the closure of the coal fired generators which could not be switched off at night and needed something to power during the night time.

However, problems with the nature of the metering, and the potential expense of the shift, are barriers to the migration of hot water systems to the day-time hours.

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  1. George Darroch 3 years ago

    I wonder if solar isn’t also making us better domestic consumers of electricity.

    When you know when your electricity is ‘yours’ and when it’s someone else’s, you might be more careful about how often you turn on the air-conditioning and what appliances you buy.

    (Alternately, extra ‘free’ electricity could see the rebound effect that is sometimes talked about and infrequently demonstrated.)

    • Rod 3 years ago

      Spot on. The admittedly generous SA FiT (44c + retailer Fit) is a great incentive to be very energy efficient and export as much as possible.
      Smart consumers who aren’t on high FiTs will quickly work out it makes sense to use energy rather than export.
      Also, as many systems, inverters and batteries have meters, consumers have more information about how energy is being used.

      • George Darroch 3 years ago

        As commercial premises take on board solar and smart meters, they might also realise that setting the AC for 23c instead of 21 is a better investment on a hot summer day.

    • Joe 3 years ago

      George, I can vouch for myself that since I have solar and monitoring I am so much more conscious of using appliances.

  2. George Darroch 3 years ago

    We should absolutely be storing excess domestic solar, whether in the form of hot water, battery, or ice-cooling systems in summer.

  3. yahoo2 3 years ago

    The barriers to the migration of hot water systems to the day-time hours is just as likely to be interstate coal assets that still need a market at night. Why else would AGL offer me $1 per day EV charging on nightly J-tariff in South Australia?

  4. Jo 3 years ago

    “… However, problems with the nature of the metering, and the potential expense of the shift, are barriers to the migration of hot water systems to the day-time hours. …” so much about smart meters #!$#@!!#.

    • Rod 3 years ago

      The problem is most SA meters are still the “dumb” type.
      SAPN had a voluntary replacement program but I’m not sure what the uptake was.

  5. CaresAboutHealth 3 years ago

    Can you explain the problems with the metering?

    Giles wrote on 6 Oct 2016: “According to the Australian Energy Regulator, a price spike to $14,000/MWh occurred just after 11.35pm on Monday, September 5 (in SA), when demand jumped 212MW as the grid operator switched on all the electric hot water systems under its controlled load operations.”[1]

    This suggests that the grid operator can choose when to switch on the electric hot water systems, so why can’t this be done during the day if that’s when power prices are at their lowest?

    • Rod 3 years ago

      I am more than happy to be corrected by someone who knows better.
      My understanding is that we, SA, still have a LOT of dumb meters. The time for the HWS to come on and turn off is hard wired into the meter. (11:30pm-7am) This can only be changed by a tech visit.
      The grid operator may have the option to override the HWS via ripple technology or similar. That is turn the heaters off during part of that period if needed.
      It is an interruptible load and the tariff is discounted as such.

  6. Chris O'Neill 3 years ago

    However, problems with the nature of the metering, and the potential expense of the shift, are barriers to the migration of hot water systems to the day-time hours.

    This is an opportunity. I hope they take it.

  7. Michael Murray 3 years ago

    Really interesting article here about SA’s sudden change to exporting power.

    It seems the gas turbines at Pelican Point have been turned on more often. This explains why every time I look at

    SA seems to be exporting power to Vic whereas if you look at the AEMO report on SA in the article above it has a graph showing how SA imports always greatly outweigh SA exports.

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