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Ergon confirms rule changes to take rooftop solar boom off-grid

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Ergon Energy, the electricity network distributor for more than 90 per cent of Queensland, has introduced new standards – flagged here late last month – that will allow its solar PV customers to go off-grid, in a bid to cut exports of rooftop solar generation to the grid.

In a statement published on Thursday, Ergon said rooftop solar was continuing to boom in the state, with the company receiving about 1800 applications for solar PV connections a month.

The changes, it said, would allow the distributor to manage the impacts of this boom on the network, while allowing new customers to connect solar PV systems that did no export to the network, and paving the way for the addition of battery energy storage systems in the future.solar rooftops

“Ergon has 96,000 customers with solar PV installed across regional Queensland. That equates to 17 per cent of residential customers,” Ergon CEO Ian McLeod said.

“Considering there were fewer than 2000 homes with solar just five years ago, that’s an almost 5000 per cent increase, requiring Ergon Energy to manage the impacts on the network in terms of safety and reliability, while working to provide customers choice.”

As we wrote here in June, Ergon and Energex (which services the south-east corner including Brisbane) have both been moving in the direction of limiting or preventing households from exporting excess solar electricity back into the grid, despite its potential to accelerate grid defections and the so called energy network “death spiral”.

At the end of last month, Ergon confirmed to RenewEconomy that from July 1, it would allow non-exporting solar households with a capacity up to 30kVA to connect to the main grid with a reduced level of technical assessment compared with exporting systems.

McLeod described the new standards as consistent with the company’s commitment to give customers greater choice and control over how they source and use power.

Ergon today confirmed that its customers with solar PV systems with a maximum inverter capacity not exceeding 5kW export to the grid would receive a feed-in tariff of 9.07 cents a kilowatt hour, as set by the Queensland Competition Authority.

McLeod said the changes did not affect customers who already had a solar PV system and new customers would still have access to the government-mandated Queensland Solar Bonus Scheme.

“The greater benefit for customers comes from using the power derived from their solar PV system themselves rather than exporting it to the grid, so this option may suit some customers,” McLeod said.

“In the longer term, if the price of battery energy storage systems falls as predicted, then it may also create an option for customers to store the excess electricity created during the day for their own use at night.

“If the stored power is used during peak times, this has the potential to help manage future prices for all customers.

McLeod also stressed that the company believed no one would be disadvantaged by the new standards, adding that they would help keep the state’s solar PV industry viable, while reducing upward pressure on electricity prices for all customers.

“These new standards for connecting inverter energy systems (including solar PV systems) to the electricity network will allow more people to use our network for two-way flow of power,” McLeod said.

“We strongly believe our network can be an enabler of customer choice in terms of how they make and use electricity into the future.

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  • juxx0r

    I’m cool with Ergon managing the stability of the grid, and if this is what needs to be done, then so be it.

    However, with the $46B we spent over the last decade gold plating the grid, and now it seems we don’t have a dime to upgrade systems so that we can take more solar; that’s clearly not true, it’s that they don’t want more solar.

    • Chris Fraser

      Maybe not – i think the original 2007 plan for grid investment was Capacity for everyone to run a 20kW airconditioner on hot days. They forgot to include in their shopping list step adjusting transformers embedded in the system to control local voltages. Now the money’s been spent and there is nothing to stop PV from overwhelming the system ? The conspiracy appears to be, for all consumers who don’t install a lot of PV, their choice of energy source is limited to centralised generators both clean and dirty – and excludes their PV abundant neighbours from a few streets away. This is a step backwards away from democratic energy trade – a slowly closing shop.

      • juxx0r

        I get that what has been spent hasn’t been for this purpose, but:

        “In some cases, customers have their applications to install PV systems on constrained sections of the network downsized, unless they are prepared to pay for an upgrade to the network.”

        So can’t the network pay for the upgrades? Isn’t that their job?

        • Chris Fraser

          They could facilitate any upgrade needed, whether that be network grunt or tweaking network voltage. Policies that either welcome PV or discourage it will probably determine how they invest.

    • Winston

      The “grid” is the whole grid: it goes all the way to the Eyre Peninsula and down to the bottom of Tassie.

      Lots of solar can destabilise the grid in ways you wouldn’t expect that have nothing to do with Ergon’s assets. Often, the issue revolves around what happens when a big load (like Boyne Island) or generator suddenly disappears from the grid because the network protection schemes tripped (in response to lightning, equipment failure, etc). The grid experiences a rather nasty spike or dip in voltage. The problem is that solar inverters are set up to be pretty finicky where the grid is concerned. It’s doesn’t take a big spike to make them trip off.

      Now consider what happens when a really big chunk of electricity is being supplied by solar, and a big load or generator suddenly disappears. You get a big dip or spike, the AC frequency starts changing too quickly, and all the solar inverters trip off at once. Suddenly you’re well short on generation, the voltage dips even more and the grid shuts down.

      My guess (I don’t know for sure) is that the no-export option is an isolation mechanism designed to prevent that cascade from happening. Or to prevent the situation from getting worse while they figure out what to do.

      In Germany, they mandated that all the inverters controlling > 10kW systems had to be retrofitted. All 315,000 of them. At a cost of between 65 and 175 million Euro.

      simple explanation: http://www.solar-inverter.com/en-GB/797.htm

      complicated explanation: http://www.ecofys.com/files/files/ecofys_2011_paper_on_frequency_stability_challenge.pdf

      So yes, they’ve been spending an awful lot of money on the grid while totally missing something important. This issue is about something “not-grid” (lots and lots of tiny little inverters) affecting the grid in an unexpected way and it totally blindsided the lot of them. But it got the Germans, too. Gonna be some bumps on the road to the new world.

      • Chris Fraser

        That’s an important trip mechanism because that also protects rooftop solar systems, which are monitored nowhere near as intensely as grids and capital assets. I get that this says we can’t put more dependence on solar energy supply through the day, because it is also a victim of grid stability due to other events which are completely unrelated to PV. I would consider that just another failure in design. It sounds as though for those few critical seconds, the network may need to employ a buffer, like embedded capacitors or Ultrabatteries to smooth things out. I have heard they can respond very fast.

        • Winston

          A synchronous condenser will do the job. But running synchronous condensers is an ancillary service, and ancillary services don’t pay enough to recover the cost of the condenser. The cost would end up being on the network operator, who would pass it on to the end customer.

          All these solutions involve bolstering the grid, paid for by everyone, so that the people who install solar panels won’t break it. You’ll see plenty of people around saying that isn’t fair.

          Personally I think it’s worth it if it means clean air. And once everyone has solar panels it’s no longer an issue ;-)

          • Chris Fraser

            I’m just glad that an industry person has come on here to explain it. Many professionals may read, few contribute. Of course we as PV energy traders will pay, but we get the benefits also. This scenario sounds like a much more secure grid than we have been used to where a tree across a powerline miles away keeps us out for days !

          • juxx0r

            My issue is that they gold plated the grid for their ends, but won’t even give it a dulux makeover for our benefit.

      • Jules

        The 50.2Hz issue is a uniquely German problem. In Australia, residential solar PV grid connections are governed by AS/NZS 4777 and the setpoint for over-frequency trips is 52Hz for 2s. You would need a seriously insane amount of load rejection to get 52Hz for 2s in the NEM. So I really don’t think that’s the reason behind the no-export option.

        I would prefer to take Ergon’s statement at face value. Their contention is that certain distribution feeders are underrated and customers aren’t able to install the size of PV array that they want, i.e. Ergon limit the size of the arrays so that their weak feeders don’t overload. So with the no-export option, the customer can install whatever they like.

        That said, I do think that policies such as these are actually providing incentives for people to defect from the grid, since you would almost certainly need storage to make the most out of PV without grid export. And grid defections are probably not what Ergon actually want!

        • Winston

          Sure, but it’s the under frequency situation that’s the issue, since tripping generation in over frequency is corrective. Also, it’s the rate of change of frequency that instigates the trip, not just the frequency itself. Recent charts shown on this site by Giles show just how much solar is contributing (http://reneweconomy.com.au/2014/energy-prices-crash-as-queensland-solar-takes-hold-21256). The big plant are off or running at minimum generation and system inertia is low. Things ain’t what they used to be (thank the gods). The standard is being reviewed.

          It’s probably not an issue in Qld as long as QNI is in service, but if the trip is QNI itself under high import conditions things might get hairy.

          I find the weak distribution feeder thing a bit odd. The feeders were built to provide capacity towards the customer. To overload a feeder the solar capacity would have to be so high as to not only supply all the consumption in an area, but supply the same again in export, running the feeder in reverse. I’m not sitting in Ergon’s control centre, so I hardly know if that’s what’s happening. You’re probably right; the cynic in me is saying that they’re not all sitting around there worrying about anything beyond their little patch.

          The grid defection thing is interesting. They charge based on energy used, and solar is digging away at their (regulated) income. It doesn’t matter if people defect or not – as long as the sun is shining they’re not getting paid (daily fixed portion of the tariff aside). If people do disconnect their capacity problems go away.

          Personally, I think of this whole thing as Ergon single-handedly kick-starting the next phase of the renewable transition: the stabilisation of renewable generation through, as you said it, storage. It had to happen some time. It’s a kick in the guts for everyone, though, for that to happen through a no-export policy. The same people who would stabilise the situation by installing storage won’t be able to help the grid when the grid needs them!

          • Jules

            The point with the 50.2Hz over-frequency tripping in Germany is that a huge chunk of PV (they say up to 8GW) could cause an under-generation scenario, thus leading to an under-frequency issue, i.e. it is overly corrective!

            But you’re right, frequency stability has always been the biggest issue with low inertia renewable energy sources (e.g. EirGrid’s system). That said, I’m generally unconvinced it’s a huge issue in the NEM. The biggest single generating unit in the NEM is probably the 700MW Eraring unit in NSW. In QLD, the largest units are smaller ~350MW. In a system with >20GW of generation in service, I doubt a single unit trip would cause that much frequency variation to have widespread ROCOF and under-frequency trips.

            QNI is also double circuit 330kV, so you’d be pretty unlucky to have both circuits trip out. Furthermore, QNI has historically exported power from QLD to NSW (90% of the time) and QLD has almost never imported more than 200MW.

            Anyway, rather than operating on gut feel, I should probably run some simulations of these cases to see what happens…

            As for the distribution feeders being underrated, my hunch is that the problem is less to do with the feeder itself and more to do with overvoltages at the distribution transformers (which are likely to have fixed taps) when power is being exported from lots of residential PV.

  • Matthew Wright

    So they are going to allow some nominal feed-in say 5kW. Does that mean that you can install a 10kW inverter with 20kW of panels and set it to maximum export of 5kW and they will greenlight that configuration fairly quickly?

    Does it also mean that an inverter can be set to zero grid export while waiting for relevant approvals then the installer can return to the site (or do it remotely via the internet) and change the inverter export setting to 5kW (or whatever the maximun standard approved amount will be)

  • Alen

    Considering QLD FiT bonus scheme ran out July 1 and retailers are willing to only pay pittance for the kWh exported, I will be more than happy to make my next PV system (sunnyboy with in-built storage) a non exporting system.

  • Miles Harding

    The start of Ergon’s long walk from the tar pits?