Solar Modification

[TealCanady]

Hi all,

I'm curious if any Roadster owners have taken it upon themselves to modify the roof into a solar panel or if anyone has even considered it? I'm curious if the extended range would be worth it in places like CA. Any thoughts?

Teal Canady

[doug]

A simple back of the envelope calculation would show that given the surface area available, the extended range would decidedly NOT be worth it.

Should add that it can make sense to run some ventilation fans, stuff like that. But not for adding range to the car. Not with current PVs anyhow.



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[TealCanady]

Ya I suppose the charge would be insufficient to warrant the panel. I was mainly curious if anyone had done the math, with a 2 sq ft solar panel on the roof and a 3 hour drive assuming ideal conditions for the sun would the roadster get a 5 mile boost or 20 miles..Guess we'll have to wait for the solar tech to catch up.

[dpeilow]

Not with current PVs anyhow.

Even if they were 100% efficient, the extra range from a Roadster roof would be a few miles on a sunny day at best (hint, lookup solar flux, local sun angle, etc).

[OppositeLock]

Ya I suppose the charge would be insufficient to warrant the panel. I was mainly curious if anyone had done the math, with a 2 sq ft solar panel on the roof and a 3 hour drive assuming ideal conditions for the sun would the roadster get a 5 mile boost or 20 miles..Guess we'll have to wait for the solar tech to catch up.

I love back of the envelope computations.

First, let's make some assumptions about your 3 hour drive. Let's assume that it's high noon for the entire three hours and you are at the equator. Given these conditions, we can assume that sunlight delivers about 1.4kW/m2 of energy, so a two square foot panel will yield 260W at 100% efficiency. The best solar cells available are less than 50% efficient, so let's halve that, 130W of power from the solar panel. Over three hours, 130W produces 390 watt-hours of electricity. According to Tesla Motor's web page, the Tesla Roadster consumes about 15 kW of power at 60 mph, meaning our 390 Wh of solar energy is enough to power it for about 1.5 minutes, during which you will have traveled 1.5 miles. So, it's definitely not worth it

[mpt]

Don't forget charging loss; i.e. 80% efficiency at best... so about a mile or so.

That could be an important mile one day!

Interior ventilation would be my choice for that power.

[TEG]

Taken to an extreme, with maximized efficiency, and covered with solar panels, you can make a vehicle that can do freeway speeds on solar power...

http://www.wired.com/autopia/2009/10...lar-challenge/

...A Japanese team has won the World Solar Challenge, racing across the Australian outback an an average speed of 63 mph to wrest the title from a Dutch team that’s dominated the past four races...

[TealCanady]

Thanks for the replies all. A mile is definitely not worth it but given the billions that are being poured into solar it may be possible one day to extend the range using solar paint / panels with increased efficiency. Ideally of course you would like unlimited range during the day but I don't see that occurring in my lifetime.
I'm guessing its probably the same story using the wind generated from driving. The S seems to have a small 4 slat opening on the hood which wind will come through, but probably only another mile range to the car: ) Thanks again all.

[mt2]

I'm guessing its probably the same story using the wind generated from driving. The S seems to have a small 4 slat opening on the hood which wind will come through, but probably only another mile range to the car: ) Thanks again all.

Oh, no, no, no. Don't even start with the wind turbine thing. The physics are so simple that even I understand it. As the wind turbine converts air movement to electricity it creates drag. Since there are loses in the conversion and storage, you don't gain as much energy as you lose with the drag. Hence, you actually reduce your mileage. If you decided to use the turbine to intentionally slow the car, you would not recapture as much energy as the regenerative braking already does. It's an all around bad idea that keeps popping up.

[doug]

It's an all around bad idea that keeps popping up.

This monstrosity combines both:
EarthSure Announces AirRay, A Solar And Wind Powered Electric Car - Green Diary



I guess because of email, people don't use envelopes anymore...