I'm frustrated with Ford regarding their inability to let buyers know a delivery date. I want to purchase a new care now. I would most likely purchase the Ford Focus instead of the Nisan Leaf based on my experience with Ford products. The Leaf is attractive because its avaiable now.

Ford, PLEASE provide some delivery and price otherwise I will have to settle for the Leaf.

^? From Nick's article above:

"According to a Ford press release, at launch in late 2011 the Focus Electric will be available to consumers in..."

I thought "late 2011" was pretty clear. Whether Ford can hit that release window remains to be seen. We'll likely know more in a few months.

The cost of the solar roof would greatly exceed the amount of electricity the roof generated over it's lifetime. It does sound like a great idea, covering the roof of an electric car with PV cells to generate electricity, but in reality it isn't much more than a gimmick. As others here have pointed out, cars aren't typically in direct sunlight all day and even if they were the electricity generated would be minimal.
If you had the entire roof a huge solar panel it would only generate enough electricity to move the car a mile or two a day. At most, in perfect conditions it may generate 1kWh of electricity and the car could go about 4 miles on that. I can see it being used to power accessories like the A/C, radio and heater, but even then the cost probably doesn't outweigh the benefit.

What one has to remember about PV panels built into roofs of EVs is that they aren't there to completely charge the vehicle. They can't. But they can be VERY useful and practical for powering climate controls when parking for short periods out in the open.

Remember that both the interior heating and cooling on an EV is going to be electrically generated. On hot days down here in the desert, I would welcome stepping into a car with the air conditioning already on. Likewise, wouldn't most northern climate dwellers like the heater to be turned on upon entering their cars when its freezing outside?

The danger here is that one could deplete the battery while keeping there car's interior climate controlled all day long, say, on a very long shopping excursion (forgetting to switch it off, etc.) But I think that being able to normalize interior temperatures for even a few minutes before having to enter the vehicle on excessively hot or cold days is a marvelous use for these built-in rooftop PV panels. That you don't have to turn on an ICE and pollute the air to do it is a real plus.

@dgcolorado . . . Yes, all valid points that you bring up. I realize that PV panels have to be oriented perpendicularly to the sun's rays for optimal performance (park your car on a 32° incline due south,) and that a rounded roof, heat, weight of protective covering over silicon chips, etc. are all working against the idea.

But 100 to 175 Watts? That's at least SOME free power that can be put to good use. Even non-cooled air circulating for a few minutes before entering a 110° F interior would be a plus. It would certainly work far better than the "As Seen On TV" underpowered fan-blowing gadgets - with a paltry few square inches of cheap PV film- that are inserted into a partially opened window.

Whenever I see for/against arguments regarding built-in PV panels on car rooftops, the overly-optimistic exclaim "charge as you drive" possibilities while those who have a more realistic grasp of the technology are often too quick to dismiss any benefits whatsoever.
I guess I'm somewhere in the middle (glass half full . . . even if its a small glass) and can see at least some potential usefulness in the idea.

Now, would I, as abasile points out, spend $4200+ for such an add-on at the showroom? Not on your life. I had no idea that this is what new Prius owners were being asked to pay for this option. I could get a lot of rooftop panels for my home (agreed that this is the best place for them) for that kind of scratch.

Although I don't have it, I have seen a study from a very competant source that shows a good return from a small PV array on a car (EV or ICE) if it is used to power a vent fan. It turns out that an automobile air conditioner is sized to cool a car that has been sitting in the sun all day down to a tolerable temperature in a few minutes. Since a car in the sun can get extremely hot, this temperature is way above ambient (ie: at ambient T's of 100F, the inside T could exceed 130F). This makes the necessary A/C unit way larger and less efficient than needed for normal use.
A small, solar powered vent fan can bring the inside temp down nearer ambient temp and this allow the manufacturer to put in a smaller, more efficient A/C unit while still meeting the customer's desire for a tolerably cool car in a few minutes.

I agree that powering a fan off the traction battery might be just as good and is probably cheaper but solar power is cool. :-) People will be willing to pay a fee bucks ( as shown by the Pruis offering this option) for a cool factor that actually accomplishes something real, even if the cheaper alternative you propose will also work. It's all good!
On further support of the solar option, if a car is left in long term parking for a long time, this PV may keep the hospital loads (clocks, computers, etc) from running down a small aux battery as often happens on Priuses and ICE cars.

@Benjamin Nead, that sounds good to me! I'm hoping to see aftermarket add-ons become reasonably economical sooner rather than later. Happy New Year.

@Keith, That's interesting and I am not surprised that the main battery is isolated when the car is off (or that the accessory 12 V battery has "issues"). However, there could be ways to use a small amount of power from the main battery if it was so desired. The reason I suggested it was to point out that the amount of power produced by solar cells is so tiny that they have little cost-benefit when used in a sub-optimum location such as a car roof (or hood or trunk deck). Especially given their fragility, weight (if protected by glass), the needed wiring, and so forth.

In my view, "ex-EV1 driver" had it exactly right when he pointed out that the reason for solar cells on an EV was the "cool factor". People do spend money on less useful options on their autos, after all. But to pretend that they produce enough power to be cost-effective is just wishful thinking. That was the point I was trying to make.

If keeping the accessory battery charged is the goal, there are other options, such as doing a better job of controlling "leaks". Or parking the car in a place where it can be plugged in.

Perhaps I'm in the minority, but I prefer to garage my cars (and there is no sun in my garage). Next to my house, a car is the most expensive possession I own and leaving it outside to be damaged by weather seems foolish (UV from the sun is especially harmful). To do so because it has a solar roof makes no sense to me. (Yes, I understand that people are talking about parking outside while shopping or at work. Better to find or install covered parking in my view.) But, then, I tend to keep cars for two decades or more, rather than trade in for a new one every few years. It is a different mindset.

@Darren,
Actually, you probably won't have any trouble with a 66 mile roundtrip commute in the Leaf or Focus EV. Heavy traffic won't actually hurt you much, only the extra time with the Air Conditioning running.
I agree that the option to buy a little extra range is a good idea but Tesla seems to be the only company that understands this - maybe thats because they have a 2 year head start on selling EVs.
If you want a little insurance that is easy though, you might want to investigate plugging in at work. 120V charging will get you about 25 extra miles of range during an 8-hour day.

@Mike Streadwick, How many solar panels one needs to offset the amount of power used by an EV depends on a number of factors:
Latitude, angle of panels (I adjust mine ten times a year), ambient temperature (the colder the panels the more power generated), weather (of course), and so forth.

It would be inefficient to have solar panels used just to charge an EV with no provision to store the power when not used or tie it to the electrical grid. The reason is that solar panel output varies with time of day, season, and weather. This wouldn't provide the steady power needed to adequately charge an EV. It could be done, it just isn't very practical.

Most of us have "grid-tied" systems in which the PV panels and inverters are connected to the regular power grid and excess power generated is supplied to the grid to be used by someone else. This is monitored by a dual electric meter that shows how much power is used and how much excess was generated. That power credit can then be used at other times of the day or other days when the power production is reduced. The exact details of how grid-tied PV systems work depend on the state and power company.

It is possible to connect the PV array to batteries and store the power to use directly but this is more expensive and is usually done by people in remote areas away from the power grid.

The amount of power that a PV array can generate can be estimated based on one's location and climate. It is usually expressed as an average number of hours per day times rated panel output. For example: if one has a 1000 watt array and over a whole year it produces 1500 kwh of power, that works out to 4.1 hours per day times rated capacity. (But this is an average, in winter or on cloudy days output is lower, perhaps much lower, and on sunny days it can be much higher.)

For my system, my 700 watt array generated 1164 kwh in the last year (which works out to about 4.56 hours times 700 watts). FWIW, that was about 75% of my total household usage over that time. [My PV array is quite small compared to most, a typical household system would be in the 2000 to 5000 watt range, depending on household power use.]

If one assumes that an EV will use about 0.25 kwh per mile, then my 1164 kwh generated would be the equivalent of about 4656 miles. The mileage traveled will vary depending on speed, weather conditions, altitude, use of heating and cooling, and the like. Lower urban speeds will need less power per mile and higher freeway speeds will need more, because air resistance (drag) increases as the square of the velocity.

Given those numbers, I plan to double my solar array this spring so that I will generate enough power to offset the miles of a future EV and still have some left over to offset some household use. (I don't drive that much and some of my miles are on a bicycle.)

You might want to talk to a solar installer in your area to find out how much power solar panels typically generate where you live. You can then determine how big an array you would need to generate enough power to provide the number of miles you expect to drive in an EV.

Anyway, that's a general idea of how it all works. [As an aside: living in the snowbelt, I have found that the best way to remove snow from solar panels is to use a window squeegee on a long painter's pole. That pulls the snow off without damaging the panels. Works better than a broom or snow rake.]