Are your figures, notably 4-6 hours of generation, overlooking the potential for home battery owners to buy power in during off-peak (cheaper) periods, for either their own usage, or for selling back to the grid, at other times?

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XorNot 2 days ago | parent [-]

I've costed it and it doesn't work out. But you can realize why without doing the calculations: unlike solar, batteries aren't surface area limited. So better capitalized producer can achieve better economies of scale and just build warehouses of the things to do exactly that. Which is what they do - and thus off peak power trends towards a tiny margin over the warranted kWh cost of a battery.

	▲	Jedd 2 days ago \| parent [-]
		Okay, I think you're in a different part of the world to me, then - I can generate about 85kWh in a day here, mid-summer, about 34 degrees south, and that's throttled by my 10kW inverter. I could go higher with a better inverter, but energy providers in Australia, or at least my part of it, basically drop all pretence once you go over 10kW feed-in, and the already pitiful rates they'll offer as standard asymptote towards zero. Time of usage tariffs vary quite wildly here, but it's not uncommon to have close to 70c at peak hours, and 20c at off-peak. These fees are complicated by the daily connection charge, which is around $1.00 but varies on your location, provider, and your ToU and other schemes. Some 'pretend to be a wholesaler' options exist here, but our wholesale pricing is bid and sold in 10m blocks, not 15m, as per your other note. Also, we have ~6 hours a day where peak pricing is generally applied, and maybe ~9 hours where we're at off-peak pricing - so the math tends to be more compelling.