Days of autonomy

Hello, are there any resources that can help us determine the recomended autonomy days for a certain location?

I would recommend working out how much excess storage would cost compared to what alternative charging means - like a petrol generator - would. And some over-panelling. Considering the price of panels and petrol, compared to battery ones, I would wager that anything past one rainy day of storage is counter-productive. I may be wrong.
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