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# Ford looks to the sun with concept model

• Ford (F) plans to unveil a solar-powered concept car at the Consumer Electronics Show in Las Vegas next week.
• The automaker says the sun could provide enough power for 75% of all the trips of a car such as the C-MAX Solar Energi Concept.
• Industry watchers will be keen to hear the driving specs Ford thinks a solar-powered vehicle can deliver in the future.
• Probably works great in Vegas. How about in Seattle?
2 Jan, 07:24 AM Reply Like
• 1980XLS
, contributor

Solyndra on Wheels!
2 Jan, 08:06 AM Reply Like
• Arthur Fisher
, contributor

Like a lot of us older guys, maybe it slows down a lot towards sunset?
2 Jan, 08:27 AM Reply Like
• capeman228
, contributor

What does solar powered mean? Solar at home with a plug in? Solar panels on the car?

I assume that they are putting solar cells on the car and I wondered what that could do, so I did the following quick calculations to see how much difference solar could make:

How many watts do we need?
One gallon of gas contains an energy equivalent of about 33kwh, and a gas engine is around 25%efficiency. An hour of driving in a small car will consume between .5 and 2.0 gallons an hour. Let's assume 1.0 - so a typical small car which consumes a gallon of gas in an hour will require about 8000 watt hours of energy. We'll need to supply our little car with about 8000 watts an hour from the sun if we want it to be really solar powered.

How Many Watts do we get?
Suppose you plaster solar cells all over the car and get 40 sq ft - with a very efficient panel, that will produce about 640 watts when the sun is shining. Electric motors are more efficient than gas ...80% is typical but lets assume we have a 100% efficient motor.

We can tell from the gas engine example that we need about 8,000 watt hours of useable energy.

But the solar panels will have produced only 640 watt hours...or less than 6% of what is needed.

This will work fine if the sun always shines and you take long breaks between driving sessions. Very long breaks. But for someone who drives only an hour a day, that electric contribution could become very substantial.

On the other hand, if the efficiency of those solar cells gets much above 15% it could become an even more substantial contributor - especially for light duty cycles like commuting.
2 Jan, 01:10 PM Reply Like
• Tdot
, contributor

Cape - You can look at the referenced article for details, you know, by clicking the live link on the highlighted word "unveil". All sorts of answers to your questions are there! Reading it just might help you with your understanding and comprehension!

Also here is Ford's article: http://ford.to/1eYG0br

And another version: http://ford.to/1eYG2jl

Anyway, it isn't a solar powered car, it is a solar powered battery charger on the roof. The current rapid chargers used at home and at public charging stations typically use 240V AC and operate at around 6000 watts. The slower extension cord type base "overnight" chargers use 120V AC and maybe 1200 watts.

Of course, Tesla has their own unique charging strategy, but that's not important right now.

Full on direct sunshine at sea level contains about 1000 watts of radiated power per square meter, after some 340 watts per square meter are absorbed and scattered by the atmosphere. Those roof panels look something like roughly 3 square meters?

You can do the math from there, yes?

The vision is to partially recharge the battery on sunny days while it is sitting idle in the parking lot at work, school church, the mall, whatever, sort of like if you plugged it into a 120V outlet.

What might be interesting is whether the thing can gather enough solar power on a sunny day to sort of limp the car home at low speed if everything else fails.
2 Jan, 03:34 PM Reply Like
• capeman228
, contributor

Yes, I realize this is a hybrid...my point, perhaps poorly worded, was to see how many minutes of driving would be contributed by the solar cells. In other words, are the panels worth the effort, not to mention the loss of moon roof!

My calcs used 16 watts/sq foot from a panel, which is achievable with premium current production panels. Your figure of 100 watts per sq m is more typical but I assumed in this app that they would use a high end cell.

The point is, with cells on roof and hood you would get at most 640 watts *8 hrs or 5kwh per day which amounts to somewhere in the range of 40 minutes of drive time per day. Not bad, really.

(Actually, the Ford article claims 8kwh collection, but I think that they have some external concentrator lens at work).
3 Jan, 12:43 PM Reply Like
• Tdot
, contributor

Goodness Cape, if you actually read the articles (please?) you would see that Ford stated that on a sunny day the solar cells would charge the battery enough to cover 75% of daily commuters' daily commutes, absorbing about 8 kW-hr, equivalent to a 4-hour charge off the grid. The typical EV gets roughly 3 to 4 miles per kW-hr, so let's say 24-32 miles of range per solar charge.

Ford did the math and expounded on it for you, there is no reason to speculate and guesstimate!

Also, as previously stated, the solar radiation available at sea level for conversion is 1000 watts per square meter, not 100 watts. And again, in the article you should READ (!) Ford is using the newest most advanced high efficiency solar cells available with special Fresnel lenses to focus and amplify the radiation to the solar collectors as the sun "moves" across the sky.

3 Jan, 01:04 PM Reply Like
• capeman228
, contributor

I think you will be hard pressed to find a collector capable of producing more than about 16 watts per square foot. Check out the current SUNPOWER panels - they are the manufacturer for Ford on this project. It really doesn't matter how much power hits the earth, only how much the panel can produce!

Fords numbers are interesting but incomplete. There is no way that they are collecting 8kwh on that little panel without EXTERNAL lenses, something that aggregates incident radiation for a larger area and concentrates it on those panels . My math did not include that lens so I came nowhere close to their 8kwh per day....I was addressing the panels themselves only.

There is no picture of that lens in the press release that I saw, nor is there any price placed on it. I just did a google search, tho, out of curiosity and found a carport looking thing associated with the project and that is probably what they have in mind.

But my guess is that this external appliance will be the least practical part of the whole shebang. For commuters, it would have to be located at the location where you keep the car during the day, of course.

As for 'Ford did the math for you...so no need to speculate' - well, you are more confident than I in press releases....I always expect them to be a bit of truth and a bit of spin.

Hats off to Ford anyway for the effort; if you are going to spend money on a solar panel it does make sense to put them in a vehicle that already has the storage capacity and electric controls, not to mention one that displaces inefficient gasoline usage.

Plus, as I pointed out, you do get about an 8% duty cycle. So you could be driving through death valley, run out of gas, and still continue after a refreshing (long) walk in the desert.
3 Jan, 03:33 PM Reply Like
• capeman228
, contributor