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Comment by chrisamiller | Hacker News Reader

A quick analysis of our local (St Louis) rates for an average (1700 sq ft) suburban house indicate that time shifting to get peak rate savings isn't worth it:

Payback time on the 10kWh battery would be around 26 years, and on the 7kWh battery would be 33 years.

So, at least in the midwest, I think you'd have to be either using a ton of peak energy or coupling the battery pack with solar to make the investment worth it.

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And as long as utilities are forced to buy back electricity at market-or-higher rates, there's zero incentive to every use a battery system with solar.

It's perfect for data centers that need UPS and generators for outages.

Isn't that the idea though? Solar + battery + electric car = no gasoline, electricity, or natural gas bill.

If the average car gasoline bill is $3000/year, electricity is $1000/year, and we demand a 5-year payback, we can spend at most $20,000 on a solar+battery+car system over what we would spend on a conventional gasoline-car and grid-house.

Yeah, that's the primary use, but there has been speculation here and elsewhere that a battery could be worthwhile just for exploiting the difference between peak and off-peak rates. This indicates that, at least for my area and usage, the answer is no, it's not worth it.

Unless we actually started taxing carbon emissions, in which case you could see those numbers change very quickly. I'm not saying it's likely, but you can't assume your future payments for specific items will stay consistent years in the future.

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