I think it's less a question of batteries being economical, and more a question of the relative economics of batteries vs solar panels.

After all, if the highest demand is between 16:30 and 19:00 you could use batteries to store power at 12:00 and sell it at 18:00 - or in famously sunny Australia you could build enough solar panels that solar output at 18:00 matches power demand.

If batteries have a solid 9% return on investment, but solar panels have an even better 12% return on investment, panels will outpace batteries even though the batteries are a decent investment.

(Also, from a politican's perspective, making batteries highly economical is how you get batteries built. And an awful lot of pro-environment policies involve raising taxes, banning things and creating new chores; it's nice to have some green policy announcements that actually benefit voters in the short term.)

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perilunar an hour ago | parent | next [-]

> you could build enough solar panels that solar output at 18:00 matches power demand

No you could not. For half the year the sun has set by 18:00.

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sevenseacat an hour ago | parent [-]

I mean in the dead of winter, yes. For six months of the year? Definitely not.

	▲	perilunar 26 minutes ago \| parent [-]
		Definitely so. Unless you are on the equator, the sun is up for less than 12 hours a day from the autumnal equinox to the spring equinox. The sun will set before 18:00 local solar time. So apart from funkiness with time zones and summer time (which extends a couple of weeks past the autumnal equinox in Aus), yes, roughly half the year.

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danmaz74 4 hours ago | parent | prev [-]

You won't get 12% return if your panels generate electricity which is only paid between 18 and 19, because there is already overcapacity between 16:30 and 18.