More rooftop solar needed to reduce peaks, stabilise grid | RenewEconomy

More rooftop solar needed to reduce peaks, stabilise grid

Days after ACCC calls for rooftop solar scheme to be abolished, new report identifies why more rooftop solar should be encouraged to reduce peak demand on hot days and boost system security.


Days after the Australian Competition and Consumer Commission called for federal incentives for rooftop solar to be abolished, a new report has identified why more rooftop solar should be encouraged – to reduce peak demand on hot days and boost system security.

The analysis from The Australia Institute looks at the three critical days over the past summer, when demand soared in the worst of the heat-waves, and major coal generators tripped – helping push prices towards the market cap.

The TAI looks at how rooftop solar delayed and reduced peak demand across the National Electricity Market, in some cases by up to eight hours and by up to 2000MW.

“This improved the reliability of the grid, covering for coal-fired power plants during breakdowns,” it says.

ACCC chairman Rod Sims, a long time critic of rooftop solar incentives, called for the small-scale renewable scheme (SRES), which offers upfront rebates on solar system purchases, to be abolished by 2021.

He based his case on the fact that the rebates were costing all households up to 40c a week, but his analysis included no assessment of the benefits of rooftop solar, which the likes of network owners, the CSIRO, and the Australian Energy Market Operator say will account for nearly half of all supply by 2050.

The TAI study makes clear what those benefits are. “When demand was highest this summer rooftop solar reduced peak demand by over 2000MW, the equivalent of a large coal power plant,” the TAI’s Ben Oquist says.

“Household solar also stepped into the breach, more than compensating for the large breakdown at Loy Yang B power Station, which occurred during another period of high demand.”

AEMO has identified that hot days present the greatest challenge for the country’s electricity system, because demand soars and gas and coal generators often fail in the heat.

“Our system now struggles to meet peak demand without rooftop solar and other renewables,” Oquist says. “The great thing about solar is that it reliably produces power on hot, sunny days, just when we need it.”

Indeed, NSW energy minister Don Harwin – in the state with the most dependence on coal power, and home to some of the most unreliable fossil fuel generators – has credited rooftop solar for moderating prices and avoiding power shortages in heat waves in both 2017 and 2018.

“We often hear that solar doesn’t work when the sun doesn’t shine. Fortunately, the sun does shine, a lot, exactly when we need solar most,” Oquist said.

The TAI analysis shows that rooftop solar delayed peak grid demand in South Australia, by eight hours on one hot day, and over six hours in Queensland. (See two graphs above).

“If governments are serious about energy security, providing incentives for solar panels and batteries should be a key priority, rather than building more unreliable coal and gas plants,” it says.

“As more households install batteries, this effect will last further into the evening.”

In South Australia, the previous Labor government had looked to boost system security through a series of schemes that would provide rooftop solar and battery storage for low-income households, starting with public housing.

These schemes included a proposed 250MW virtual power plant from Tesla, comprised of rooftop solar and Tesla Powerwalls installed for no deposit in 50,000 homes, and a separate scheme to install rooftop solar and sonnen batteries in another 10,000 homes.

However, since the election of the Liberal state government in March, these schemes have been put on hold. A spokesman for the government told RenewEconomy this week that work was continuing and an announcement would be made soon.

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  1. Graeme Harrison 2 years ago

    Ah, the South Australian government, like all LNIPA governments before it seeks to kill off progressive renewables projects, without acting coming out and saying that they are being killed off. Thus far, just permanent deferral. Of course the election platform they stood upon was that they would continue the excellent work SA had done on renewables… As always, judge them by their actions, not their words. The big donors of the LNIPA will be in there seeking to white-ant all renewables, and to sign-up for Josh’s plan to back-pedal nationally on renewables.

    • PLDD 2 years ago

      I am pretty cynical about government promises. But I reserve judgement about SA. It only about 4months since the election and in that time the new energy minister has been positive about these schemes. Let’s wait until the announcement before jumping to conclusions.

  2. Rod 2 years ago

    Maybe the idiotic SA Liberals need to look up the word “soon”.
    As far as I can see they have done nothing since coming into office. Except of course, bag Labor at every opportunity. Very similar to the last time they were in and we had a recession during most of it.
    Neoliberal, trickle down, austerity sh*t only works for some. And it won’t be housing trust residents.

  3. Andy Saunders 2 years ago

    And don’t forget the hidden factor – shade.

    Rooftop solar comes in roughly 1.5m2 panels, which produce around 0.28kW or so each. But they also block the solar insolation onto roofops – around 5kWh/m2/day (more in summer) – or around 1.5kW of heating per panel. Some of that would have been reflected away anyway by the roof, and ceiling insulation blocks a lot more, and then a heat pump (AC) is typically used to remove the excess heat internally, at a ratio of maybe 3:1. But each panel may reduce the power demand on the AC by 50W or so (maybe more, maybe less) just by shading the roof…

    • Rod 2 years ago

      Why the benefits of shading aren’t pushed has me perplexed.
      My own experience of a noticeably cooler roof space and house after installing a second array has me convinced shading should be a consideration.

  4. Ian 2 years ago

    Well done Giles, this insight is needed to counteract the actions of powerful groups like the accc.

  5. JackD 2 years ago

    Unfortunately it would seem that Liberal Govts (or LNP/Coalition Govts) / Govt aspirers are good at promising and then delivering nothing earth-shatteringly far-sighted. Vic’s Ted Bailieu (Liberal) rode the coat-tails of ALP predecessor John Brumby efforts, and just opened Brumby’s projects. Ah hang on, Baileau did do something – he effectively curtailed the development and deployment of wind turbines through severe planning restriction (controls). And lets also not forget Campbell Newman’s LNP pursuit of Abbot-like evangelism on pro-coal anti-solar activitism in Queensland.

    Interestingly and oddly, the NSW Coalition are not as against Renewables as one might expect and I guess that this can only be a good thing. However, NSW has a LOT of catching up to do on the Renewables front.

    Reading into SA’s history, it seems that its been a long time since they had a progressive conservative government (Playford oversaw the building of ETSA and this gave SA its power network). Yes, this was built on coal generation (like Victoria’s SEC as overseen by Monash) but at the time all of this was far sighted.

    SA has a proud of history of social progression but progressive government has only (in recent memory) come from the ALP (Dunstan, Bannon, Rann, Weatherill/Koutsantonis) with intervening Liberal Coalitions hell bent on undoing the progressive work. The new SA Liberals are not likely to be any different. In the fullness of time, I feel history will judge Jay Wetherill and Tom Koutsounis rather favourably and the SA people will sigh and pine, for some similarly far sighted to come forward and lead the next progression.

    And if SA gets its way, despite its Liberal Government, it will leverage its high concentration of renewables, to build a competitive edge for attracting business to it. One can only hope that the Liberals don’t get in the way.

    • Paul Surguy 2 years ago

      The Port Augusta power station was built for black coal that came from Port Kembla then went to brown or burning dirt as some would say

      • JackD 2 years ago

        I thought SA had Black Coal like NSW rather than the Lignite (Brown Coal) found in Victoria but I admit that I haven’t properly researched that aspect. Perhaps ETSA changed over to Brown Coal for similar reasons to Victoria, which was that Black Coal was expensive to import from NSW and was subject to relatively unreliable delivery (Miners and Train Drivers strikes). The yearly reports show that this issue plagued Monash and his Electricity Commissioner colleagues with it ultimately resulting in the development of Brown Coal generation in the Latrobe Valley.

        I haven’t also read up enough on Playford in regard to his push for electrical development in SA. However like the SECV’s role in Victoria, Playford’s ETSA was instrumental in developing industry in SA and developing SA as a whole more generally.

        As I stated in previous post, the development of these State Government Electricity bodies were quantum leaps forward in centralising delivery of electricity of a uniform standard and in a reliable manner. A far cry from those early electrical developments built by Local Government controlled activities in many state jurisdictions.

        Moreover generally, if we’re going to have a distributed electrical system to facilitate the sharing of power across groups of users, then we need to utilise our transmission and distribution assets to their maximum potential.

        Whilst batteries and Hydro can provide stability and storage to spread the bursty nature of renewables generation, the ubiquitous grid is a necessary component in achieving balance of power flows from supply rich sub-regions to high demand others. Supply regions are likely to feature multiple personalities, going from Supply Excess to Supply Shortfall perhaps in the course of a few hours or possibly for several days or weeks at a time.

        Finally, SA for example is a classic resource rich wind generation facility (with a growing resource solar generation facility) but has limited demand (currently). It has abundant areas of excellent wind and solar prospectivity but especially so, out in the remote regions. In fact some of highest solar resource prospectivity areas in the world, are found in SA.

        We should be exploiting this in the same way other resources have been developed across this wide brown land.

        • Paul Surguy 2 years ago

          The black coal was supply by ship,the state wanted to supply itself and do it the Playford way which was great,also other projects were Playfords doing

  6. Ray Miller 2 years ago

    With the addition of the extra GW’s of solar this year of both small systems and solar farms, the peak reduction WILL break last summer’s record.
    For the ACCC to be competent, they should have valued the NEM support of PVs at a critical time? If PVs saved at least one state from load shedding how much was that worth?

  7. George Darroch 2 years ago

    The 2018-2019 summer will be hot and the sun will shine. And there will be a lot more solar, both domestic and commercial. The peak-shaving events that these are creating will be even longer and larger.

  8. Ian 2 years ago

    Looking at these graphs you can see that rooftop solar is just less than 1/2 way to meeting the daytime peak demand . That’s with about 7GW installed across the country. The openNEM widget clearly shows that black coal can vary its out put by at least 20% and it does that every day, or about 4GW of variability. Gas and hydro are fully dispatchable which gives another 4GW of leeway, We also know that home hot water heating is a large component of household consumption and can be shifted to the day possibly giving another 4GW of slack in the supply demand balance . We are probably looking at another 10GW of solar installed before any storage becomes essential.

    At some point storage will be needed to timeshift solar, perhaps at the 17GW mark. Why not shift the LGC’s to only apply for solar or wind plus storage. Ie a large scale renewables developer can only receive the LGC if they have a certain amount of storage eg a 100MW farm would need to install 100 MWH of storage to get the LGC.

    Or perhaps the STC could be doubled, but only linked to 1kWh solar plus 1 kWh storage, (1:1) ratio. ie, no storage ,no stc. 1:1 ratio of storage, double the existing STC

  9. saugato mukerji 2 years ago

    The next step which will further increase the benefit of roof top solar to home owners without depending on higher feedin tarifs is simple. Home owners pay 34c/kwh when they consume the utility company supplied energy and only get back 6c/kwh when they feed in. It would make great sense to reduce the peak home solar PV output and increase the number of hours over which the PV output is produced. It is simple split the number of panels( say 20) into 3 or 4 groups (of 5 or 6 ) and allign each group to maximise the output in different time slots i.e 6am to 10am 10am to 1pm, 1pm to 4pm and 4pm to 730pm. So instead of a 5kw system producing a peaky output i.e. 20kwh between 11 and 3 and 5kwh before 11am and after 3pm The output can be flattened resulting in something like. 5kw between 6am to 10am, 4kwh between 10am and 1pm, 4kwh between 1pm and 3pm and finally 4kwh between 3pm and 7:30pm
    Though the daily power production at 17kwh there is a greater potential for reducing the number of kwh purchased at 34c/kwh, which has a far greater financial impact than exporting excess kwh at 6c/kwh.
    A more sophisticated study of the power consumption pattern of the home from sunrise to sunset over the year is necessary to arrive at the optimal size of the groups aimed at the morning, mid day and late afternoon. This data should be available from a smart meter and should be the reason to install a smart meter that can provide continuous power consumption data digitally.
    With falling price of PV panels we should now think of installing excess panels so that peak output of the inverter is delivered from each full capacity bank of panels facing NE, N , NW and W.
    An average home consumes 18kwh per day in Australia. The water heating load is often 30 to 40% of the energy use. Further refinement of home solar PV can be done where, offpeak water heating is being used by switching the excess solar PV output to the water heating before feeding it back to the grid for 6c/kwh.

    On the surface these measures seem to be reducing the grid support provided by Solar PV on hot summer days of high peak demand. But in reality by increasing the financial return on Solar PV to the homeowner by the strategic flattening of the peak and widening the hours of the Solar PV output, the potential for adoption of Home Solar PV is greatly improved.

    Potential adoption can go from 25% in 2017(5.7GW) to double or triple this figure.

    Flattening the peakiness also has the benefit of reducing the stress of the amount of energy storage capacity needed to balance the peaky and volatile nature of renewable energy. Reducing the energy storage needed will be very helpful in speeding the transition to zero net emissions by 2050.

    To summarise the economic return from Solar PV to the home owner can be boosted by strategic flattening of the peak PV output to avoid paying the full 34c/kwh tarif for 10 to 12 hours instead of the current 5 to 6 hours. The benefit can be got by splitting the available panels into 3 or 4 groups and alligning the different groups to peak for the morning, mid day and late afternoon sun positions to flatten the peak but widen the power delivered by the panels to the home.

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