Dear EcoGeneration,

I am writing in response to your article published on 27 May entitled What solar traffic jam? … a role for the networks in tomorrow’s solar-filled grid. The article contains some inaccuracies and misconceptions that require a response.

In reference to networks (outside of Victoria) having little visibility of their LV networks, your quote that “It’s been a perennial problem for the networks forever – and they just didn’t really care…Now they are being forced to care” is somewhat disingenuous.

Australia’s electricity distribution networks (DNSPs) are expected under regulation to manage voltage efficiently and at least cost to customers. Prior to the advent of rooftop PV, this involved dominantly a single issue: the fact that voltage drops along the line at times of high demand. By ensuring network voltage was high enough at the substation at times of low demand to allow for voltage drop under load, this was achieved effectively and efficiently for more than 100 years without the need for extensive monitoring of the low voltage end of the network.

With the advent of rooftop solar, the traditional, simple approach no longer works as we now have a significant amount of energy injected into the customer-end of the network in the middle of the day, which causes voltage to rise at that end. Essentially, we have had to double the ‘dynamic range’ of our LV networks.

What is needed now is more active management of voltage during the course of the day to keep it within bounds both at times of peak load, when voltage still drops as it always did, and at times of peak solar output, when it now rises. This in turn requires greater visibility of voltage in the LV network. This issue has arisen entirely from the growth in rooftop solar over the past 10 years.

Networks understand this issue, and care about it. If you read any DNSP regulatory proposal from the past ten years – all of which are in the public domain – you will find that networks in high-solar regions have been flagging this issue and the need for investment in improved voltage management and greater network visibility for many years.

It is certainly true that network voltages are generally in the upper part of the allowed range much of the time, as the UNSW report has found. What is not true is the suggestion that this is evidence that ‘the problem has been there all along’ or that it has been ignored. It is perfectly acceptable for network voltage to sit at the upper end of the range at times of low demand, like overnight, for the reasons explained above.

It is also wrong to suggest that voltage issues can be trivially fixed. If it were as simple as just ‘lowering the voltage’ across the network then that would have been done, as networks have a regulatory obligation to maintain voltage within the allowed range, and no reason, commercial or otherwise, not to do so.

In South Australia we are making steady progress in reducing daytime high voltage issues, in particular through a recent program of upgrades of voltage management systems in 140 of our larger substations supporting 790,000 of our 900,000 customers, so that we can raise voltage in the evening to deal with peak demand and lower voltage during the day to facilitate solar exports.

But voltage management relies on physical assets at all levels in the system, and there is much more work to be done. In South Australia, we have more than 70,000 low-voltage transformers across the state, none of which can be adjusted without a truck visit, and many of which are old units that can’t be adjusted at all.

Some of our zone substations are already at the lowest transformer tap, meaning that voltage can’t be lowered further without a significant upgrade. As your article observes, greater network visibility is a key piece of the puzzle and one we are working on.

The article also perpetuates a common misconception that DNSPs lose revenue because of solar. This is simply untrue. DNSPs are regulated businesses that operate under a fixed five-year revenue allowance set by the Australian Energy Regulator.

Revenue is set following a detailed process of considering customer service frameworks and reliability and other targets, network needs and stakeholder input. That revenue is then recovered over time through network tariffs, whether energy sales rise or fall. This means DNSPs do not lose money when customers install DER or generate their own electricity. Nor do DNSPs have any role in the buying and selling of solar energy – that’s the role of retailers.

In fact, DNSPs benefit from the transition to distributed energy, as it means that an ever-increasing portion of the overall energy system is connected to and feeding energy through the distribution network, increasing the value and importance of the networks that we are responsible for.

Again, we would urge interested readers to have a look at DNSPs’ recent regulatory proposals, which are published on the AER’s website, to see what DNSPs are actually doing to upgrade Australia’s ageing distribution network infrastructure to enable the incredible uptake of DER.

In summary, while we agree that generally high voltage levels in the distribution network are a significant immediate challenge to accommodating higher levels of DER, and we agree that the lack of visibility of voltage in LV network outside Victoria is a key gap that needs to be addressed, it is entirely wrong to suggest that DNSPs are not working actively to address these issues because it is somehow against their commercial interests. The opposite is true.

Our goal at SA Power Networks is to double the amount of solar on our network by 2025 and we wholeheartedly support the transition to distributed energy. It is unequivocally a good thing for DNSPs, as it is for Australia and the planet, and we at SA Power Networks are working hard to actively support customers and the DER industry to enable and accelerate this transition.

Mark Vincent
General manager, strategy and transformation
SA Power Networks