Given that your short (i.e. 10 miles) commute costs about $1 in utility rate electricity (at 20c/kWh, .5kWh/mi), to be worthwhile, the solar panels would need to cost far less than the $2 per day that such a commute costs. Accounting for rainy or cloudy days, and the inevitable dirtying of the solar panels, it's unlikely to be worth the expense in economic terms, to say nothing of the aesthetics.
It would make more sense to use the money to put solar panels on your house, if generating your own energy for commuting is a priority.
That's why I maintain that the only value of on-car solar panels for daily commute purposes is for hybrids with small batteries (which are Toyotas strategy) since the alternative to electricity in that case is using petrol, which typically costs 2x per mile compared to electricity.