First of all, 95% of the time appears to be a number you pulled out of your ass. No offense.
Second of all, 95% uptime for residential housing needs would be rather irritating. It would amount to almost an hour and fifteen minutes a day. For heavy industry it would be a lot worse though. Shut down the power to a manufacturing plant, or a microchip factory, or a foundry, and you end up scrapping an awful lot of product. I know this, because the company I work for scraps product once or twice a year when the power goes out.
Thanks for the link though. I always like it when opponents help me prove my point!
Translation: they don't have to bear the full cost of wind power, because they can just buy electricity from France's nuclear plants (which run 24/7) when the wind is not blowing very strongly.
Suppose I came over to your house every day, and flipped off the main breaker in your electrical panel. Then I put a padlock on it, and kept it off for 73 minutes. Every day. Or instead of every day, let's say that I did it for 18 days out of the year. 18 full 24 hour days, with no power.
You'd be okay with that? No, you'd be fighting mad.
It's certainly doable for residential, if you're willing to make certain sacrifices. The main obstacle isn't even the cost of a battery stack, it's the fact that lead-acid batteries only last 4~5 years. Hopefully Firefly's batteries will cure that: NiMh performance at lead-acid prices, in a battery that lasts for decades.
Don't be too hasty. Rising energy prices combined with nanotech have produced a wave of new storage devices. And even if the carmakers had no interest in battery tech (not true), the laptop and cell phone industry certainly does.
Google the following:
firefly battery
A123 battery
altairnano
EEStor (this one will really make you shit a brick)