South Aus $200 mil big battery paid for itself

So why haven't they built three or four more.
The chart below shows how little impact $200 million dollars worth of battery has on the unreliables system.

How many billion $ more batteries will they need to fill the gaps left by the unreliables?
And if they are so profitable, why have they wasted the last 5 years in building more?

Battery input can be seen in blue.
Wind is green and solar in yellow.