Comment by JKCalhoun

I would love to see this laid out practically.

For example, if you had an electric golf cart with a solar roof, on a sunny day…

With two adults, a speed of 35 MPH, an LLM suggested a ratio of 10:1—that is, the power demands of the golf cart were 10x what the solar could deliver in real time. (LLM considered also aerodynamic drag, rolling resistance of golf cart tires…). When I suggest a speed of 25 MPH, the ratio came down to 5:1.

Regardless, assuming batteries to store energy on the cart, it suggests a 10 minute drive to your neighborhood grocery store would require the golf cart to sit in the parking lot for close to an hour before it will have caught the batteries back up to their charge before you left home. (And this is at the rather impatient 25 MPH drive.)

To get to a better ratio you would have to engineer like hell to start squeezing the numerator. Make it radically aerodynamic, low-rolling resistance tires (probably the lowest hanging fruit), cut the weight significantly…

I do love the idea of something like an electric rickshaw or tuk-tuk. Maybe not streamlined, but you could get much better rolling resistance with something like bicycle tires—and weight could be kept in check.