Word has leaked out that the next-generation Toyota Prius will offer optional solar cells on the roof manufactured by Kyocera. Yahoo! News reckons the new system, rated at least 2kW, should be capable of powering the air conditioner unit. The current Prius and other Toyota hybrids already have an electric AC unit. "Adding solar panels to a model targeting mass consumers would mark a first for a major automaker", The Nikkei said. Ahem. Let's flashback to fall 1991, courtesy of the New York Times archive. The last generation Mazda 929 had 500W solar panels on the sunroof. The cells ran exhaust fans in conjunction with the AC unit (the Mazda's chiller wasn't electrically powered). The rooftop solar system could trickle-charge the battery from dead to full steam ahead in one week– assuming the 929 was parked in Arizona during the dry season. The old system was perfect for the airport long-term parking lot. It'll be a lot harder for the Prius to make this work on a daily basis, but the PR benefit for both the ToMoCo hybrid– and solar technology in general– is literally priceless. Even before it turns a wheel, the next gen Prius has trumped Chevy's plug-in electric – gas hybrid Volt.
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I’ve been wondering when either Honda or Toyota would add solar panels on the roof to a hybrid vehicle. I was assuming Honda would be the first since they have a solar panel plant operational in Japan (which they’ve found a way to product panels with substantially less energy and materials).
Wow! I’m happy to see this.
I just drove my (MID-SIZED) 2008 Prius from the gas station (the only one in the area which now sells pure gasoline) – it’s slightly down hill to downtown and there was some country driving and also town driving. I did manage to get almost all of the lights on green, too.
Computer shows 77.1 mpg. Parked next to a new Subaru Impreza (SUB-COMPACT) and the sticker on the window showed 17 mpg city, 23 highway.
The future Subaru hybrids can’t come soon enough, and Subaru needs to start working on them NOW, with their new partner, Toyota.
If Ray Kurzweil is correct in saying photovoltaic solar power will double in capacity and halve in price every 18 month’s (Moore’s Law) then it won’t be long before we’ll see this feature on most new cars.
The aircon must be the obvious place to start – if there’s enough sun to warrant having the aircon on – there’s enough sun to power it.
What about the solar powered air conditioning through panels on the sunroof of the Audi A8?
Oh, wait. Now every time an inventive piece of history is reintroduced through anachronistic hypermarketing, Toyota is happy to take credit.
Where did that 2kWh figure come from? And why use a unit of energy to rate the panel? Is that 2kWh generated in one whole day in the Arizona sun? By my calculations, standard ~15% efficient solar cells on the roughly 1 square meter of Prius roof would generate about 150 Watts continuous in strong sunlight.
That’s good though – who wouldn’t like to get into a car that’s maybe only 90 degrees instead of 125 degrees?
Wasn’t Ford going to use photo cells in the Edge to power a venting system. The idea was to keep the interior cooler, especially with the Vista roof. It doesn’t mention this feature on the Edge website so I am assuming that it didn’t make it to the final product. Anyone else remember this?
Menno, it’s disingenuous to call a Prius (96.2 cu/ft passenger space, 14.4 cu/ft cargo) a “midsize” and call an Impreza (94.4 cu/ft passenger, 19.0 cu/ft cargo) a “sub-compact”. Not to mention the fact that you are comparing your MPG from a quick jaunt to the gas station to the average MPG of the Impreza STI version!
GREAT!
Hope ya can still get a sunroof in it, tho.
Toyota builds sunroofs on their cars, Chrysler makes a new 6 litre HEMI.
I guess we all have to spend our r&d dollars on something…
We have 2 Prius’ now; our 2004 has been doing a lot of duty parked with the AC on since my wife is on crutches (while I’d go get a wheelchair for her or something); the new one has been used exclusively by me for commuting.
Current reading on the ’04: 45.1 mpg; on the ’08: 52.9 mpg.
It does make a difference; and having the solar A/C would help a bit. But people need to realize that’s about all it could run – it’s very unlikely it would even be worth hooking it up to the hybrid battery
@tn4601: I wasn’t aware of the Audi A8’s solar powered fan, which appears to do the same thing as the Mazda 929’s.
@bolhuijo: this report of the Nikkei article, the original appears to be subscriber-only.
Actually, its a bigger deal then you think…
Each one of those cute little “leafy” icons on the Prius display means you recovered 50 Wh of power for later use.
At 2 KW, the solar cell during the day is equivelent to 40 of those precious “leafy” icons an hour. Park it in the sun all day and you can get a nontrivial boost to the batteries.
Thus putting a 2 KW solar cell on the roof is a nontrivial benefit.
bolhuijo makes a good point. As soon as I read the article, I thought to myself that I must have missed a major improvement in solar panel technology. Last I heard, the best you could get out a Prius-sized roof would be 500 W/H at best. I checked Kyocera Solar’s web site and found the same old solar panels I have seen in the past, although Kyocera claims 16% efficiency instead of 15%. This warrants further investigation.
Yeah, Prius = Midsized and Impreza = Compact according to http://www.fueleconomy.gov
Looks like Menno made the same mistake others make classifying a car by the appearance instead of the measurements.
My only experience with solar power comes from using survey equipment. My company has a GPS survey system at one of our operations. One of the components is a base station at a fixed surveyed location which sends radio signals to the mobile antenna we use to mark points. The base station runs off of a solar cell and is good for one day and night of continuous operation. If you forget to turn it off before going home, it will have little left the next day. The solar cell is about as big as a car roof. It’s great for this low-power application, but I’d be hesitant to run an air conditioner on it.
2 to 5 kW – that’s outstanding! Let’s assume they’re not using concentrator technology – only crystalline or thin film cells. Furthermore, let’s say they have super hi-tech cells with 25% conversion efficiency. Standard insolation is 1000W/m^2, so to get the 2kW, they need 8 square meters of solar cells on the roof. Given the dimensions of the current gen Prius, it casts a shadow at high noon of 7.66 square meters. My conclusion: Toyota plans either a HUGE size increase for the next Prius, or some elaborate folding panel technology to be deployed while parked, which will have the side benefit of providing shade for the other cars parked nearby. Either way, I totally want one.
Correction noted on the Impreza. It’s a COMPACT.
Still, you can see how discordant it was to pull up next to a small-ish car and see “17 mpg city” on the sticker.
Pretty damn poor, no matter the performance, for a small car.
I did also mention that I’m typically around 52 mpg with “real” gasoline, 48 on the 10% ethanol sh!t. Not trying to pull a fast one, just wanted to share the major dissonance of pulling up next to a new Subie (yes, I think it was the performance version).
I prefer the performance of my Prius. 0-60 in about 10 seconds (with a reasonably charged – as normal – traction battery), tops out at 106 mph (faster than any US or Canadian speed limit, or most European ones, for that matter), and it PERFORMS at 45 mpg and up while doing pretty much the same duty as any other mid-sized car (D-class car internationally).
“Subaru Impreza (SUB-COMPACT) … 17 mpg city, 23 highway.”
Subaru’s insistence on weighing all their products down with AWD drive-trains is a big disadvantage when customers are paying close attention to fuel economy.
“If Ray Kurzweil is correct in saying photovoltaic solar power will double in capacity and halve in price every 18 month’s …”
Almost none of Kurzweil’s prognostications are well founded, including this one. Solar cell technology has been around almost as long as integrated circuits and is indeed improving over time, but nowhere nearly at a Moore’s law rate. Moore’s law is grounded in the ongoing miniaturization of feature sizes on a silicon circuit which has managed to continue apace for a long time. Those of us who work or have worked in that industry often speculate about the point at which Moore’s law will run smack dab into the Law of Diminishing Returns. That is in itself and interesting and lively debate, but solar cells are not part of it. Moore’s Law is not a law of nature like Newton’s laws of motion, but is rather a shorthand observation Gordon Moore made by the observation of industry trends and their underlying technological reasons. Solar cells, unlike integrated circuits, are a bulk conversion process and have enjoyed only the long, gradual improvements in efficiency and cost one expects from an economies-of-scale and competitive market dynamic. Thus, solar cells are on a price:performance improvement curve similar to that of automatic transmissions or air conditioning from the 1950s to today.
Menno is right that 17mpg for a compact car isn’t good enough anymore. The goalposts have shifted, and not just for big SUVs.
As of July 1, gas stations in Oklahoma had to post signs to inform customers whether the fuel has ethanol in it. The legislature finally did something right. Unfortunately, there’s still some wiggle room. Some pumps say “May contain ethanol” or “Fuel may contain up to 10% ethanol.” In my view, if there’s any ethanol the signs should say “Warning! Adulterated Gasoline!” I’ve taken my patronage to a station that says flatly “Our fuels contain NO alcohol.” On my last long road trip I noticed my mileage ran about 1.5 mpg less than in the past. Now I realize it was probably because I was unwittingly using adulterated gasoline.
That would be awesome if the car could pre-cool the cabin, or keep it semi-cool while parked. Now we can leave pets and babies in the car!
driving course,
You obviously haven’t heard of the Great Lakes region! Here, it is routinely 80+ degrees and overcast in the summer :).
They sell solar powered exhaust fans you close the window on. As seen on TV.
http://www.coolest-gadgets.com/20060517/solar-powered-ventilator/
Nicholas, you’d never achieve 2KW (theoretical peak capacity) in any given hour – even in direct sun. You might approach it once in a while, but average would be far far lower. The cells would have to be perfectly flat and perfectly perpendicular to the angle of the sun’s rays, which would have to be unobstructed for that entire hour by anything – even the mere wisp of a cloud.
That being said, if it’s cheap, I’m all for it, because I have to park in the sun anyways. But don’t make the mistake of overselling it.
I suggest reading the article on Yahoo. They down play its significance. Calling it symbolic at best. They state the same as many posters about the limitations. A PR move at best for Toyota, and kind of a foolish one IMHO.
There is no point comparing an STi to a Prius. Nothing about the STi (gearing, AWD, turbo, etc.) is made for getting good mileage. Not everybody wants to drive a Prius. Some people think the performance/MPG tradeoff of an STi is worth it, and they have the right to feel that way as long as we are all paying the same amount for gas.
According to Edmunds, you can get solar-powered ventilation (not A/C) on the Maybach 57S, so it’s not just Toyota that’s putting solar cells on car roofs. I wonder if Rush Limbaugh’s 57S includes that feature (c.f. article on $100 fill-ups)?
“What about the solar powered air conditioning through panels on the sunroof of the Audi A8?
Oh, wait. Now every time an inventive piece of history is reintroduced through anachronistic hypermarketing, Toyota is happy to take credit.”
Classic….also so true. How many people out there think Toyota invented the gas-electric hybrid vehicle?
This works for me.
I live in Florida. Maybe I could also charge my iPod, cell phone, bluetooth earbud, laptop computer, and wristwatch from my Prius solar charger.
I’d be willing to pay more for such an option. As for “how much more,” I’d have to give that some thought.
I’ll second what my fellow Floridian ZoomZoom said. The option for a solar powered exhaust fan to keep the car cool in the sun would be a no-brainer in this climate.
tn4601:
What about the solar powered air conditioning through panels on the sunroof of the Audi A8?
Oh, wait. Now every time an inventive piece of history is reintroduced through anachronistic hypermarketing, Toyota is happy to take credit.
What about actually doing some research before making silly statements and assumptions?
The Audi A8 has a solar sunroof, NOT solar panels on the roof. There is a difference. The Mazda 929 has the same thing, as does the Maybach. The 929 and A8 sunroofs power a conventional fan, NOT the entire A/C system.
So yes, this WOULD be “a first for a major automaker” assuming it’s true. The Prius would have the whole roof covered in panels, not just the sunroof and also it would power the A/C unit, which has not been done before.
People are already doing this… http://www.thegreenmotorist.com/index.php/prius-converted-to-get-100-mpg-and-solar-power/
So Richard…
Are you going to correct Yahoo’s (your own?) mistake, and make it 2 KWH kW and 500 WH W?
Hint kW is a unit of power, i.e. 1 kW = 1.341022[…] hp. kWh is a unit of energy, i.e. 1 kWh = 0.03412128 therm = 3412.142 BTU.
TTAC is usually pretty quick with these corrections…
OK, I have new blades for my hack saw, when can I change roofs?
Engineer:
So Richard…
Are you going to correct Yahoo’s (your own?) mistake, and make it 2 KWH kW and 500 WH W?
Hint kW is a unit of power, i.e. 1 kW = 1.341022[…] hp. kWh is a unit of energy, i.e. 1 kWh = 0.03412128 therm = 3412.142 BTU.
TTAC OCDs rock! Text amended.
I don’t think Toyota claims to invent these things. What makes their using them meaningful is (a) the way they integrate them in the system, and (b) the fact that they implement these innovations in a car that many people actually buy. (When was the last time you saw an A8 or a Maybach with solar panels?)
Saving energy and reducing pollution is difficult and requires a level of attention to detail that most auto makers apparently are unable to muster. For us, our Prius is a rare example of what industry can accomplish when a well-funded corporate project is tightly focused on a single goal (minimizing emissions in the case of the Prius).
Toyota certainly deserves a lot of credit for trying out these solar panels manufactured by Kyocera.
Hope the experiment works because mass producing solar panels for a popular car could bring the costs down and make solar panels more practical for our home use.
@Engineer: thanks – it’s been a very, very long time since physics class that obviously didn’t stick.
I remember the 929 system, and with the abundance of gadgets on modern cars, I was always surprised others were slow to follow suit.
I think this makes a lot of sense. Even if it’s not enough juice to run the A/C by itself, solar-powered ventilation would be a godsend much of the year. And extending driving range just by being out in the sun is a happy thought.
I just hope it doesn’t require a moonroof, like the Mazda system did. I *HATE* sunroofs. (Something about their inherent tendency to leak in the rain.)
Even if you are only getting 1 kW out of the solar cells, thats 20 leafy-cars-an-hour…
Look at it this way, if you are doing a plug-in prius to house-power, its probably not going to want to draw more than 10A (or 1.1 kW) anyway when plugged in, lest you need to rewire your garage.
So solar or plug, same difference.
However, it probably isn’t worth the money, as 1 kWH is less than $.15, so at 8 hours/day * 300 sunny days, that comes to only $350/year worth of juice for your plug-in prius, yet 1 kW of solar cells is still >$5K for that application today.
Wait a couple of years for the NanoSolar cells to get high-production: they can conform to the roofline easier and are cheaper. As a $5K option, its “No way in heck”. But if it was $2K or less for a practical 1 kW, it would be a decent deal.
Without using the uber-expensive space grade cells the most most your could get out of the roof of a car would b 200-300Watts per hour.
There is no Moores Law for PV. Solar cells get 2-4% cheaper and more efficient per year.
Sill a good idea though, if I lived in a hot climate I’d gladly pay a bit more to have a car that is 90F vs. 120F+ after being parked in the sun for 6 hrs.
Fellow Floridians: I have found the perfect way to keep one’s car cooled; park in the shade. I know this might seem obvious, but I see so many people who go to the mall and park in the sun instead of the covered garage, that maybe it isn’t that obvious.
Another trick, if you have a sunroof, you should leave it tilted open when parked in the sun in order to let the hot air in the car circulate out.
I found that cracking the windows in Florida did very little – but it sure does a lot here in Texas, with the lower humidity.
Another nail in the coffin for the Electric Vega. Toyo didnt get their reputation selling gimmicks.