[jacquesm]

That's a very expensive battery for the given capacity. If you want to be efficient check out the gel batteries used to power golf carts and forklifts. You'll need 24 2V cells if you want to do this efficiently both from a cost perspective as well as to reduce line losses between batteries and inverters. (24 and 12V are really not adequate for larger power installations).

[IgorPartola]

Such as these? http://www.batterystuff.com/batteries/golf-cart-products/

I don't really see orders of magnitude jumps in power/$. Or am I looking for the wrong thing?

[jacquesm]

No, more like these:

http://pics.camarades.com/v/jacques/renewables/batteries/IM0...

Sold in bulk. That's a 48KWh bank and it cost about $US 5K

[IgorPartola]

This is roughly 2.5 times cheaper than the marine battery I found first, definitely not orders of magnitude.

This is $5k for 2 kW * 24 hours. So 3 of these at $15k total would roughly replace my $700 generator + $10 worth of gasoline for emergency situations.

To truly run my house where it would be adequate at 20 kW or 24 hours or so, I'd need 10 of these at $50k. To run my house of for a week (where I live, the last major power outage lasted three weeks), I'd need $350k. For that amount of money, I can just buy a very nice house in Florida and go down there when the power goes out.

Now, if I go top of the line, I can get a 22kW generator (http://www.homedepot.com/p/Generac-22-000-Watt-Air-Cooled-Au...) for $4,700 + gasoline at $2.30/gallon where I live. This will not even require me to go out and start the thing as it kicks on automatically, much like a battery backup does.

Battery powered houses just don't make sense cost-wise, and at this price disparity it's not a question of spending a little more: $350,000 vs $4,700. That's two orders of magnitude. It's not the clean option, but given that it's standby power, I'd rather see us invest in more efficient power plants (nuclear and wind) than home batteries.

[jacquesm]

I think you're more than a bit power hungry. My house consumed < 5 KWh max per day, so even running to 50% discharge that bank would power the house for up to 5 days.

It's much easier to save on consumption than to create capacity, especially stored capacity. You don't really realize just how much energy goes into AC, heating, washing and so on until you've lived off the grid for a bit. And then you'll quickly learn how to conserve energy. I'm currently living in an on-grid house, the old habits die hard, my computers are probably the biggest consumers here.

Anyway, if 22KW is your power budget then don't bother going off-grid without a generator.

Battery powered houses make perfect sense if you're able to conserve power, if you can't then of course it does not make sense.

[IgorPartola]

That I suppose is the line for me. I am unwilling to go to a point where I cannot use my washer/dryer, dishwasher, AC, etc. I believe the majority of the developed world is with me on this, though of course there is a minority that have other priorities.