I am looking into building something similar to these.

To charge my car from a trip to Indy, I need ~38,000 watts

Over a 6hr day – thats around 6,300 watts of panels

At 650watts a panel – thats 10 panels

I can get each panel for $220 – or – $2,200

Batteries are running around $100 per kilowatt – or $3,800

An inverter running 240v split phase at 50amps – $1,200

The total cost would be around $7,200

If power is running $.15 a kilowatt (with fees/taxes)

Figuring 280w/mile – that equals about $.04 mile

$7,200 would require around 180,000 miles to break even….