Yeah.. Like a whole bunch of others say in this thread - this is bollocks.
I got into the solar game early. I had mine installed about six years back. I got 48 of the 180W panels (there are much better now) and they cover pretty much all of my electrical use (aswell as my south facing garage). Given that used to be around $250-300 ish a month, that's a fair ongoing savings.
Now, couple that with the Green tags / SREC's which I can sell for (depending on wether gub'ner Christie is being a nobhead this year or not) anywhere between $60 and $600. Five few years back I sold a bunch for $400ish, last year I sold some for $60.
Either way, my 'payoff' is about six years, give or take a couple.
Now - back ontopic. I have a battery backup system aswell! It cost me about $3500 ontop of my installation and consists of a unit which senses the grid and shunts power to the batteries, and 4 marine batteries of some particular type that I don't actually care about. They cover the electrical usage of my house overnight if the grid is down. Not if I'm watching some huge plasma telly all night, but lights.. radios, computers, intarwebs (which.. work for all of 4/8 hours into a regional power outage, it seems that Comcast have an 8 hour emergency generator). During the (summer) day, my panels will provide power to the house and also charge the batteries enough that they'll carry me through the night again. I don't have to turn off refridgerators, clocks, I can even microwave some noodles.
I haven't done numbers. I don't care. This is real world "I have done this.. experience."
The nice thing about battery backups though is that it's instant. I don't even get a flicker if the grid goes out, or there's a brownout. If I turn off my mains my batteries kick in quick enough that computers don't reboot... If I didn't have a little alert set up to tell me when it happens I'd never even notice.
I also get alot of power outages in my area. Stupid reasons like stapling power cables to telephone poles.. which then get hit by trees, etc etc etc.
Oh.. and a few hurricanes over the past few years aswell..