The Solar Semi Range Extender

[Haxster]

While putting solar cells on passenger EVs doesn't make a whole lot of sense, it may be more practical to put them (and maybe some storage) on the trailers that electric Semis pull.

Think about it:
Lots of flat surface area
Typically in the sun a lot
Appearance is not an issue
Even when not coupled to an EV tractor, they can help power refrigerated trailers

Thoughts?

 

[Derek Kessler]

Could work for refrigeration trailers, but for charging that utterly massive battery it'd barely make a dent.

 

[BrokerDon]

Hig efficiency / able to purchase separately residential panel Panasonic HIT 330W : 65 inches x 39 inches

53' semi trailer = 636" = 9.8 residential panels x 2 rows = 20 panels x 330W/panel = 6,600W ~ 6.6kW

Unfortunately you're going to lose a significant part of that output since panels will need to be mounted FLAT on the roof of the trailer which will dramatically lower their output in winter... or the farther north you travel.

You also need to factor in:

• additional wind drag of 20 panels "dirty-ing" up the nice smooth trailer roof
• panels will add height to the trailer... potentially problematic on lower clearance overpasses & tunnels
• if Tesla Megacharger electric will be free, adding solar makes zero sense. If not, Tesla electricity would have to be significantly higher than 9¢ per kWh cost of solar (after 30% federal tax credit)

Cost of panels: 20 x $400 = $8,000
Racking, charge controller / inverter, installation, wiring = $4,000 ("Wild Ass Guess")
Total Cost ~ $12,000

Not sure adding a rooftop of solar to trailers makes sense but LOVE the disruptive thinking!

 

[Haxster]

Could work for refrigeration trailers, but for charging that utterly massive battery it'd barely make a dent.

Let's see:
15 Watts per square foot (maximum output)
40 feet trailer length by 8 feet wide
40 x 8 x 15 ~= 5 kW gross...not too shabby!

Teslarati estimates the cruising energy at ~2 kW. So, on a sunny summer day in Alaska, a Tesla Semi could run way longer on photons than the driver could legally drive (or hold their bladder).

 

[Haxster]

Not sure adding a rooftop of solar to trailers makes sense but LOVE the disruptive thinking!

If you like disruptive thinking (like self-driving electric trailers), check out this thread:
Tesla Semi Battery and Charging configuration

 

[BerTX]

I haven't looked at the numbers myself because it is silly, but something is wrong in theses numbers by at least an order of magnitude. Otherwise the transportation energy problems of the world are solved. Solar trucks for transporting goods. Solar buses for transporting people. Heck, solar trains for that matter.

I don't like to drive at night, but I guess I'll have to start, just to avoid the traffic from these things.

 

[BerTX]

Teslarati estimates the cruising energy at ~2 kW. So, on a sunny summer day in Alaska, a Tesla Semi could run way longer on photons than the driver could legally drive (or hold their bladder).

There's your hole. If my MS could cruise at 2kW, it could run for 30+ hours without stopping. Does that number seem right to you?

 

[electracity]

2kWh per mile at 60mph? So 60mph needs 4kw.

no, that's wrong

Yeah the truck consumes 2 kw at 60mph. But it takes an hour at 2kW to make 2kWh. So at 4 kW from the roof the truck adds 2 mile per hour of sunshine.

4kW would charge a 1000kWh battery in 250 hours (at 100% efficiency)

 

[electracity]

There's your hole. If my MS could cruise at 2kW, it could run for 30+ hours without stopping. Does that number seem right to you?

it can at 15mph

forget time, calculate distance

 

[Haxster]

There's your hole. If my MS could cruise at 2kW, it could run for 30+ hours without stopping. Does that number seem right to you?

Uh...yeah. You're right. I misread 2 kWH per mile for 2 kW. Sorry
Close-up look at the Tesla Semi "Megacharger" charging port

So much for perpetual motion.

Still, it looks like there could be some benefit to using solar panels on the trailer for extending the range (or saving costs) in some situations.

 

[BerTX]

it can at 15mph

forget time, calculate distance

Yep, I'm driving at night for sure if all those solar trucks are driving at 15 mph.

 

[BerTX]

Uh...yeah. You're right. I misread 2 kWH per mile for 2 kW. Sorry
Close-up look at the Tesla Semi "Megacharger" charging port

So much for perpetual motion.

Still, it looks like there could be some benefit to using solar panels on the trailer for extending the range (or saving costs) in some situations.

Maybe! For sure it may be able to supplement other loads like refrigeration. Working out the extremely variable solar output into power sufficient to add to the driving power might not be worthwhile. Charging while draining batteries is hard. From a cost and efficiency perspective, having the solar stationary and optimized is probably better than carrying it around.

 

[electracity]

A MW of solar requires about 2 acres and produces about 5MWh per day. If a typical Tesla Semi charges using 800kWh, at 80% efficiency 2 acres of solar will charge 5 trucks per day.

So a 100 acre solar farm will charge 200-250 Tesla Semis per day.

Revenue at 7 cents is $5 million/year.

 

[Haxster]

Maybe! For sure it may be able to supplement other loads like refrigeration.

Or a really robust phone charger.

Charging while draining batteries is hard.

Complicated? I agree. However, Tesla seems to have figured this out for their home PowerWall.

Of course with the Semi, there would be two charging sources: regen (from multiple motors) and solar...plus maybe a wind turbine that pops up when slowing down quickly.

 

[SDRick]

A MW of solar requires about 2 acres and produces about 5MWh per day. If a typical Tesla Semi charges using 800kWh, at 80% efficiency 2 acres of solar will charge 5 trucks per day.

So a 100 acre solar farm will charge 200-250 Tesla Semis per day.

Revenue at 7 cents is $5 million/year.

electracity,

I was hoping someone would do the math on this, thank you. Elon said the semi's would run on sunshine but I am having trouble understanding the logistics and costs. The amount of land required would be inordinate as would the number of batteries to provide charging when photons are low or absent. Will semi trucks running on sunshine pencil at 7 cents?

 

[electracity]

electracity,

I was hoping someone would do the math on this, thank you. Elon said the semi's would run on sunshine but I am having trouble understanding the logistics and costs. The amount of land required would be inordinate as would the number of batteries to provide charging when photons are low or absent. Will semi trucks running on sunshine pencil at 7 cents?

There are already solar plus storage PPAs (Power Purchase agreements) for less than 7 cents, but all the terms are not clear. Even so, I can't imagine the risk/reward of building megacharger power stations is worthwhile for Tesla. So I don't know what Musk is thinking here.

Putting solar and storage at a Walmart distributuon center to power Tesla Semi seems to make a lot of sense.

Tesla needs to stay away from commodity businesses. Bulk electricity is a commodity business.

 

[Tiger]

How much solar panel area could you fit on the roof of a semi with full trailer? Maybe also the sides? Tesla Megacharger Location thread