Tesla Semi truck unveil & test ride set for Oct 26th !

valhalla360 wrote:

dodge guy wrote:
I think this would work if they had a good solar panel system. I think with a van type trailer loaded with solar panels would greatly extend mileage.

It will be interesting!

Assuming a 8'x 50' trailer with 14w per sqft that's about 5.6kw of panels assuming 100% coverage (80-90% is more realistic).

On a typical day, the assumption is typically about 4hr at the rated output, so 22.4kw-h generated.

A semi-tractor typically has a 400-500hp diesel and climbing long grades is the use case that pushes the HP requirement (unlike a car where it's acceleration that drives the HP requirements and the low end torque of an electric motor is a big advantage). Going down the road loaded at 65mph, expect the engine to be putting out around 200hp or about 153kw.

So at 65mph, a full days solar collection (assuming 100% efficiency) will generate 8.75 minutes of propulsion.

When you figure you won't get 100% coverage on the top of the truck, the panels won't be 100% clean and you won't get 100% efficiency, if you get 5 minutes run time off the solar panels, I would be shocked. At 6mpg, that's about 0.9gal diesel per day saved. So let's be generous and assume fuel prices go up such that it's $5/day in fuel savings or 1.8% of the fuel consumption on an 8hr run.

A 5.6kw home solar array runs about $15k. Let's pretend, the truck one wouldn't cost more and wouldn't negate the energy collected by increased drag with the solar panels.
- If you got an interest free loan it would take 8 yrs to pay off but assuming say a 5% it jumps to 11yrs
- At current $2.50/gal, the 5% annual interest is greater than the annual payment. Even worse if you figure $20k solar array to make it road worthy.

Great math. I was only talking about extending the range, not for full charging. Basically supplemental to plug in charging. But it sounds like it wouldn't be enough to make a difference.