Based. >> it's charging. >> even though it's a cloudy day. >> reporter: christian says the panels can add an average 7 0 miles a week or 3,600 miles of driving range a year. more in sunny locations. you still need to plug in for a full charge or a long road trip. >> but the solar gives you that additional feature. you have around 6,000 miles in l.a. or 4,800 miles in new york that comes directly from the sun for free. >> reporter: christian and his childhood friend came up with the idea when they were 18 retrofit ing an old car in the garage. >> it's always the same problems people have with e...