Since the first utility scale solar farm was opened in Australia – all the way in 2012 – the generation output of a solar facility has a distinctive profile, and one not seen in the grid before.
One a clear day, a near perfect curve is formed the output of the facility ramps in the morning, reaches a peak in the middle of the day, and then gradually winds down in the evening.
There can be variations. Passing clouds will cause variations to the output. And, if there is too much generation and too little demand, and wholesale electricity prices go negative, most solar farms will choose or be forced to switch off.
This is the output (see below) over the last three days of that very first solar facility, Greenough River near Geraldton in Western Australia, which has since been quadrupled in size, albeit to a comparatively modest 40 MW (many recent solar projects are 10 times bigger).
The generation starts around 7am and soon after 5pm, it is finished, at least at this time of year.
That distinctive generation profile has been true of the more than 100 large scale farms added to the grid since Greenough River, but that profile is now changing, courtesy of “behind the metre”, or “DC-coupled batteries” that push that solar output into the evening peaks.
The newly connected Cunderdin hybrid facility – the biggest DC-coupled solar battery in the country to date – has changed that profile completely.
Instead of sending all its output to the grid when produced, Cunderdin is now able to store it for when the solar is more valuable. The result: A consistent, or what some would call a “baseload”, output for the whole evening peak, between 5.30 and 9.30pm.
The Cunderdin project, now owned by GPG, is doing that because it has a short term contract with the Australian Energy Market Operator that requires it to deliver power to the grid during those times.
Unlike other batteries contracted to soak up rooftop solar during the middle of the day, and send it back into the grid in evening – such as Neoen’s Collie battery that will be the country’s biggest when complete – Cunderdin is soaking up its own solar.
The Cunderdin facility features a 128 MW solar farm, with a “DC-coupled” 55 MW/220 MWh battery. Over the last three days, it has been feeding into the grid at around 44 MW or 45 MW without interruption in those key evening hours.
It may be the first at this scale, but it won’t be the last. A similar facility has begun construction at Fulham – 88 MW of solar and 120 MWh of battery storage – and some of the key projects that have won mandates in state and federal government options will fulfil a similar role.
Even wind farms, such as the new Pottinger hub in the south west of NSW – are being couple with batteries at the same connection point.
These are AC-coupled rather than DC coupled, but they perform the same purpose – soaking up output when it is not wanted or needed by the grid, and sending it out when demand and prices are higher – or when the sun don’t shine, and the wind don’t blow.
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