Because if your home is drawing electricity during the day when your say your batteries are charging that is going to decrease its charge rate. Unless this system of yours is strictly for your vehicle...

There are a few things here i have to address... First of all your saying this system will cost 12k PLUS BATTERIES. The following is a link i found to a 100 amp solar battery.A 5.5kW solar system, includingtwo dozen230 watt panels and a 6kW inverter, will set you back $12K (plus batteries). That is a moderate size solar system, which will provide peak power of 240 volts at 22 amps. This is equivalent to 120 volts at 44 amps, or a peak battery charging current of 392 amps at 14 volts DC -- sufficient to fully charge 46 of your 100 amp-hour batteries in a six hour period-

Intermec S07-101067 100 Amp Hour Replacement Batte Ry,replace

Just one i found real quick using google search. There are cheaper ones, and there are more expensive ones but generally speaking with batteries, you get what you pay for.

1 battery = $596

46 batteries = $27416

Not counting the cables needed to wire them together that is a total of aproximatly $39,416 plus the cost of a chevy volt which starts in the neighborhood of $31,000, thats an initial minimum investment of

over $70,000. I dont know many people that have that kind of money to invest in a system that will do nothing more than Put a 35 mile leash around their neck.

Do me a favor and look at how many days last year had zero cloud coverage. Then go back to my initail comment, i never said this couldnt be dont, i said it wasnt effective. Its not time effective, and its deffinatly not fiscally effective. But if you have 70k lying around with nothing to do, go nuts.In fact, with that system you could chargethreeChevy Volts every night (assuming six hours of sun every day in between, and assuming that you used the solar battery reserve for no other energy needs).