They can be depending on your needs. Lithium iron phosphate batteries are pretty cheap for their capacity. If you build your own power station with them you'd be surprised how far your money goes.

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UltraSane 2 hours ago | parent [-]

It is much more expensive that just buying electricity from the grid at night.

	▲	scheeseman486 8 minutes ago \| parent [-]
		In Australia, if you have the space for rooftop solar, it's far cheaper in the long run to buy solar+battery. We did the math for our household and even if grid prices are stable (which they aren't, they're fast increasing) we're still going to make money back on the investment in less than 4 years. Granted this includes a government rebate for the battery, but overall the prices have plummeted. Any government that isn't pushing for renewables and energy storage at this point is actively working against it's citizens.