Fears proposal to charge households with solar panels to export electricity will kill demand
South Australia is the wrong place to be looking for growth toward 100% renewable supply. The State does have more wind generating capacity than it consumes (1300 MW or so), but most of the time most of its power is drawn from (or forced onto) fossil generators in the much bigger, adjacent State of Victoria. South Australia is not isolated from fossil power at all – it is dependent on it.
A better example of reliance on renewables is the fully isolated West Australian grid, more than 2000 km to the west of Adelaide. The Western Grid has more than 1200 MW (capacity) of rooftop solar, barely matched by approximately 1200 MW of gas and a similar, decreasing capacity of coal. The coal-fired equipment must be run at more or less constant power, so the unpredictable vacillations in the solar output must be matched with gas generation, much of which is single-stage gas turbine. With the solar capacity increasing at more than 200 MW per year, the grid operator is warning of instability ahead.
People who are rich enough to own or be buying a house are given a State government subsidy to put solar panels on their roofs, with them paying the rest. Blind to the pay-off time being something like 15 years, they are attracted to reducing the power bills that help the public purse pay for the grid's operation. They are then subsidized a feed-in tariff of 7.13 cents/kWh (55 m$/kWh in USD), regardless of when and whether the grid can handle the injection.
The geography of the WA grid is too flat to speak of hydro or pumped hydro storage. As you probably know, firming by battery storage on this scale is impossibly expensive and home batteries quite inadequate. Nevertheless, poker-faced, the grid operator is changing the tariff to favor the evening feed-in (10c between 1500-2100, else 3c) "to encourage people to invest in batteries". Cheated of their high-noon profits, greedy householders will probably start buying batteries that they have next-to-no chance of ever paying off. With one third of households having solar decorations, the size of their vote will probably ensure that even more of the public purse gets hijacked for battery subsidies to again help the rich dodge paying their share of the bill for the grid.
So-called synchronous condensers are repurposed synchronous generators, often from retired coal fired plants. Such are kept rotating via a small Diesel engine. The inertia helps maintain line frequency against sudden changes.
Of interest is that the utility is using a couple of these rather than install banks of batteries for the same purpose.
(link to) "Synchronous condensers to lift constraints on renewables in South Australia"... So-called synchronous condensers are repurposed synchronous generators, often from retired coal fired plants... Of interest is that the utility is using a couple of these rather than install banks of batteries for the same purpose.
Apart from being intermittent, the power from wind generators of South Australia has unstable phase. Steam-derived power is synchronous - inherently stable. Consequently phase stability of the grid in South Australia has for many years been provided by the steam generators in Victoria, about thousand kilometres away. When a storm knocked out the connecting powerlines several years ago, the South Australian grid collapsed, plunging the state into a day long blackout.
A synchronous condenser is a grid-driven generator, outputting power back into the grid with the phase stabilised. Logically, synchronous condensers should have been installed progressively as the proportion of wind power increased. However South Australia was able to parasitise its phase control from the Victorian generators to the east.
After the blackout, the public demanded that the government fix the vulnerability. Blind to the fact that it would be hopelessly inadequate, followers of renewables insisted that a battery be installed big enough to level out the intermittency. Instead, the most expensive battery in the world was installed to flatter true believers, while the connection to Victoria was restored to provide on-demand power - and redundant phase stability.