By Phil Kreveld
Cnut the Great (c. 990–1035), also spelled Canute, was a Danish prince who became King of England, Denmark, and Norway. He is famously known through the apocryphal anecdote King Cnut and the tide, in which he set his throne by the seashore and commanded the incoming tide to halt so as not to soak his feet and robes. Of course, the tide disobeyed.
Cnut’s experience is not dissimilar to pushing back against the ‘solar tides’—that is against the irresistible force of consumer energy resources sending energy back into the grid—which was the topic ‘de jour’ at a 2024 plenary session of the Australian Climate and Energy Summit.
Of course, a network rule change was always bound to happen sometime soon, and AEMC chair Anna Collyer implied it in her interview with this journal. Charging more for network connection is going to raise the hackles not only of energy consumers but also solar owners.
The Australian Financial Review of 23 April featured the article Grid change could cost solar users $3000: “Solar power and battery owners could be more than $3000 worse off while most electricity users would have their bills slashed by 2040 under a controversial proposal to change the way households are charged for power. The proposal, floated by Australia’s grid rule-maker, would overhaul the way poles and wire operators recover their costs via consumer bills as solar, batteries and EVs change the way power is used in the electricity grid.”
Related article: Network pricing reform could deliver $6 billion in savings
Go figure
Our present annual electrical energy consumption is 178TWh. On an annualised average basis, rooftop solar represents 21GW of capacity. Present total capacity in the national electricity market is 87GW and aggregate rooftop solar photovoltaic generation, accounted for separately, is 22GW of which 18GW is the capacity net of power production restrictions. It is now largely responsible for curtailment of large-scale generation—and voltage control problems in transmission.
Distribution networks are squirming this way and that way to accommodate the rising solar tide; the latest proposal being captured in draft standard AS DR 5438. It addresses operation of solar systems for the economic benefit of their owners, and operation within power and voltage limitations of distribution networks’. The draft standard deals with flexibility in electricity generation, consumption by households, electric vehicle supply equipment (EVSE) including vehicle-to-grid operation, and dynamic operating envelopes for power export by rooftop solar installations.
Serious capital expenditure in prospect
The underlined power and voltage limitations of distribution networks is the kicker. Here are just some of the consequences. The networks used to carry I2R losses to the premises of their customers. They still carry those losses except they have gone up and up because of large amounts of reverse power flow from solar. But there’s more. To control voltage, they now carry increased Q2R losses. The distribution transformers are subjected to over-heating, and depending how far they are away from something approaching an infinite bus, subject in some cases to reverse magnetisation, over fluxing and causing harmonics. On-load tap changers are running out of range, requiring increased maintenance work—and in sub-transmission reactors have to be installed to prevent voltage rise. The willy-nilly distribution of solar on the phases has given rise to voltage unbalance and excessive neutral current, necessitating the installation of capital-intensive D-STATCOMs in ‘edge of network’ locations as well as in feeders
It’s network charges, stupid!
It’s network charges, that are a prospective problem. For Maine (East Coast, USA) they are 21 cents (50% of tariff); for California, 33 cents (40% of tariff); and in Australia, 16 cents (40% of tariff). No one need feel too sorry for the networks. They have for years been rent-seeking operations with little by way of engineering challenges necessitating more capex. But the solar tide coming in ever increasing waves has networks seeking expansion of their regulated asset base. Investment in distribution and transmission networks is $115 billion. The 2026 Integrated systems plan indicates a further investment needed of $128 billion. The current regulated asset base puts us on a par with the United States with 15 times Australia’s population. In due course network charges will swamp renewable source marginal costs.
Related article: Is the renewables transition in dire straits?
The renewable deception
Renewables are not some nirvana of low, low energy costs—or rather, never mind the ‘energy’. Think of power flow, increasingly sporadic because of ‘duck curves’, and the costs of keeping a continuous southeastern network humming. All that solar (and wind) is making for ‘interesting times’—keeping voltage and frequency in check—much of it due to distribution networks. We may be doing something for the climate but it ain’t for free.
