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Motor mammoth Toyota, maker of the famed Prius hybrid car, is rumoured to be thinking about fitting some new Prius models with solar panels. The possible move is unlikely to seriously affect the car's fuel consumption, however, and is being seen by some as a PR stunt. Toyota is offering no official comment on the suggestions, …

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Anonymous Coward

PR stunt

What's new? The whole car has been a PR stunt from the word go.

I shudder to imagine the resources wasted when do-gooders junked their old cars to "upgrade" to it, to find it's barely if any more economical than its conventional competitors.

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Solar panels in the UK?

Running the airco might be a tad optimistic, but then in the UK it would hardly be necessary anyway. it might get up enough steam to power a digital clock.

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I know I'm picking nits, but...

"However, the Prius remains the only car being driven globally which is actually different from normal internal combustion jobs in its power-train engineering."

Oh, really?

Never heard of the Lexus GS 450h?

Or the Honda Civic Hybrid?

Lexus RX 400h?

Lexus LS 600h?

And those are just mainstream cars...

Incidentally, all of those are 'normal' looking, well equipped cars, unlike the 'hair shirt and sandals' Prius.

And the Lexuses (Lexi?) are SERIOUSLY quick - 0-62 in 3.5 sec from a spacious luxury 4 door saloon anyone?

Facts right please -

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Anonymous Coward

Does Lexus not count?

"...the Prius remains the only car being driven globally which is actually different from normal internal combustion jobs in its power-train engineering..."

I know Toyota make Lexus, but the P(r)i(o)us isn't the only hybrid powertrain, and I think Lexus is pretty much a worldwide brand.

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Doubtful, but...

In counties where there's more sun than we get in dear old blighty it might be useful to recharge batteries while the car is parked... But we'd need to see figures for the rating of the panel etc. etc.

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Boffin

NOT PR stunt

Say a 1m square panel catching sun 8 hours/day (for a sunny place like California, parked outside during a working day). With a 10% efficient panel, that's about 0.8 kw/h, or 2.8 MJ.

30 Litres of gasoline is about 1GJ. So 2.8MJ is 0.084 litres of gas per day. If the daily commute uses two litres (~20 miles), that's a 4.2% improvement in fuel consumption.

To decide if it makes economic sense one has to know what the solar panel option costs. To decide if it makes "green" sense, what the CO2 cost of making the panel is, compared to the fuel saved over the life of the car.

In the UK, halve the saving. The UK is probably the worst place in the developed world for deploying solar power. Most of the world is sunnier!

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Anonymous Coward

0-62 in 3.5 sec

Im sorry, but that can't be right.

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Anonymous Coward

@ Chris re 0-62

I'm not aware of an Lexus that can do 0-62 in 3.5 seconds?! Which one do you think can, as I'm quietly confident you're wrong. ;-)

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IT Angle

"Go West, Young Man"

Finally, a car that meets the advertised dream of driving in to the sunset.

"Can't come home, low on petrol, have to follow the sun".

Erm, wouldn't chucking the solar stuff on top (not forgetting the control gear) add to the overall weight of the car? How often would the panels need changing as they would go opaque quickly due to abrasion or will they be faced with glass? Why do they keep insisting on petrol? Why is it mainly tossers who buy the things?

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Happy

New fangled technology

I am not going to waste my hard earned cash on these Solar versions...

I'll wait for the tried and tested Hydo Electric version with your own reservoir in the boot which will use gravity to drop the water down through turbines under the back seats into the foot well (passengers might need wellies) then at night when electricity is cheap pump it back into your boot. Most probably just as efficient as the solar version in blighty.

Concept tested by Toyota North Wales in the '80s:

http://en.wikipedia.org/wiki/Dinorwig_Power_Station

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Happy

RE: "....the Prius remains the only car being driven globally...."

.... which allows you to easily spot those whom in earlier times would have been sporting hair shirts. Even GM's EV1 was a better looking vehicle, and a more environmentally-friendly one. I can easily argue that a kit car built from secondhand parts is more ecologically sound solution than the Prius, and a whole lot more fun! For those who want their hair shirt in scintilating colour, there is even a gent in Essex with a Westfield with a Mondeo diesel engine (heresy!) modified to run on corn oil. No solar panels required, thank you, air-conditioning and a smile are built-in!

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It's all a stunt

Solar cells really do produce very little when compared to the output of an internal combustion engine, and the electrical requirements of a car. One headlamp is 55 watts, just go and look at the size of the panel you need to run that. (Yes I know, who wants a solar powered headlight!).

If you really want to be green and have amazing economy, you could beat the prius just by getting a small diesel from the 1990s!

Sure it won't have an aircon button to suck 10% of the engine power, but it does have these glass thing you can open, called windows. (No they're not just an operating system).

If you really want to go to town, chuck 50% old veggi oil in with the diesel, and tada, you've just halved your usage of fossil fuel.

We really haven't progressed much.

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Anonymous Coward

I Wonder How...

they intend to handle end-of-life for all those highly toxic solar cells?

Maybe they'll just crush e'm, and ship the cubes to India/China!

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It's a nice start

It might not do too much, but it's nice to see steps in the right direction. They will want add a bit of pressure for the panel to be as light as possible - and moves towards making solar panels lighter will mean that a few years later some advanced cars may start sporting bigger panel areas on the roof, bonnet and maybe even the doors.

Once that sort of area is covered, then people who only make a few short journeys each week will see their fuel costs cut by a percentage worth looking at.

For the people that make longer journeys - well perhaps we'll see some solar power recharge spots with some early adopter companies putting up a PV array to charge up their employees electric cars. Woking already has a free recharge spot in one of the car parks for electric cars to get a free refill, and since Woking also has a big photovoltaic facade by the train station you could almost say people are getting their free solar power recharge there.

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Happy

Honda Civic Hybrid, Biodiesel and FCX

The solar panel on the Prius is pure gimmick!

I spoke to the Honda salesman about the Civic hybrid. I was expecting to be able to drive for some distance on battery (only kicking in the petrol engine when it needed to (for charging etc) or when you'd gone over a certain speed. The Honda Hybrid seemed to just switch the engine off when it was idle (like the BMW/Mini Engines with Efficient Dynamics). He said for the most part - I'd be on petrol... It is apparently a power assist hybrid.

http://en.wikipedia.org/wiki/Hybrid_Vehicle_Drivetrains#Power_assist_hybrid

I'm more interested in the biodiesels and cars than run on waste vegtable oil (chip fat).

The Honda salesman did interest me in the FCX concept (Fuel Cell) and said that would be in production next year (apparently). They biggest issue is apparently getting UK petrol stations to stock hydrogen.

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Coat

Water power?

Given Tokyo's summer weather, why not add hydroelectric assist as well...

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The point is...

... when your battery starts to go it'll likely still have enough charge to get you started because of the solar panel topping it up as quickly as it drains.

I have driven three cars, two needed battery top-ups after being stood still for a long time. Solar panels from Maplin prevented this.

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Anonymous Coward

Solar panels and air-conditioning

In this part of the world (HK), the extra pollution caused by vehicles running their engines to keep air-conditioning going is a significant issue, and one that's currently being debated hotly (sorry about the pun). The government is considering forcing car drivers to turn off their engines when parked, and understandably this makes a lot of mini-bus and taxi drivers upset.

So I'd be interested to know how big and/or more efficient a solar panel would have to be to keep the air-conditioning going for, say 15-20 minutes (which would cover most stop-periods I think).

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Anonymous Coward

@Chris - Lexus

I think you'll find the actual productivity of the battery part on the 400h and 600h is extremely low. It's almost laughable. And have you seen the weight of those monsters? They should harness the power of their own gravity instead.

If they could actually power the car for 80% of the time under 30mph, they'd make sense to me. At the moment it's pure gimmick.

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Anonymous Coward

Aircon

If it provides enough power to run the aircon when the car is parked in the sun with the engine off and the windows closed, that could be worthwhile. IIRC Saab had a concept car that did that years ago.

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Flame

How much energy...

... does it take to produce the solar panel, compared to how much it will produce over the lifetime of the car?

Jeff

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Solar powered air-con?

I can see the logic of using solar energy to power air-con (when it's sunny, you need air-con) but surely there are better ways of harvesting solar power for the purpose of providing cooling?

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Prius is OK

I drove one for a week - a hire car - and it was very economical actually. It's good in town because the engine switches itself off and doesn't come on uness you do about 10mph+. You can't drive much faster than that with the battery alone. I guess for Central London it would be an ideal vehicle! The brakes charge up the battery which is a good use of otherwise wasted energy.

I wouldn't own one though, because it feels rather heavy to drive, no doubt because of the dead weight of those batteries! I would imaging the maintenance costs would be quite high too.

I'd rather buy a diesel instead, for fuel economy's sake.

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@Steve Evans

To be fair, as far as I can tell modern air-co units take less than 10%. It's also worth remembering that you can lose 10% in fual eceonomy while driving with the windows down.

You also mention using veg oil etc. Apparantly you need to be careful as this can eat the seals in some cars, plus there's the issue of HM Revenue.........

Finaly, according to Ford diesel cars are not as efficient for short journeys. I've certainly seen that for myself. Compared to a peterol car the diesel takes an age to get up to temperature and hates short journeys.

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quite a bit of power really

The roof is big enough for a 50 to 100 watt panel, which could produce quite a bit of power over time. My five watt panel will completely recharge a deep cycle marine battery in about five days. You have to remember that though solar panels produce a miniscule amount of power, if coupled with batteries, it adds up.

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Joke

Another type of solar cell

Toyota are missing a trick here. Instead of photovoltiac cells, they should use solar-thermal cells. They can provide much higher energy transformation ratios than photo cells. Use an efficient heat pump and you should be able to generate steam. Either use that to run a steam turbine generator to recharge the battery, or directly to power the car.

Burn your biodiesel/biomass to supplement the sun's heat for your external combustion steam engine and Robert's your mother's brother. In times of shortage you can use anything inflammable, white-spirit, meths, coal, White Lightning...

Mines the anorak with the Stanley Steamer lapel badge, and the Ian Allen trainspotter's guide in the pocket.

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Toyota copy Skoda.

Is Toyota now taking design ideas from my 2006 Skoda? My Skoda Superb has a solar panel in the sun roof which runs the blower when I park in the sun. This prevents the impression of “getting into the oven” after the car has been parked in the sun for any time. It saves the air con working flat out to return the interior to something like a liveable temperature.

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Cooling alone is worth having

It's a great idea. A big market for the Prius is So Cal (partly due to local pre-EV regulations), where temperature rise when parked is a serious ergonomic problem. This solar panel might do little for driving the car, but if it means the car can keep itself circulating air (and thus cooler) when parked without flattening the traction battery, then that's worth it on its own. Such cooling is well-established on boats, and AFAIR Saab did it a while back too.

As to overall efficiency, then the Prius is a brilliant way to make an urban taxi. It's _not_ a super-efficient motorway cruiser (and not claimed to be one), but i's a damned clever hybrid.

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Lexus GS450h

0-62 in "less than 6 seconds" according to Lexus. Of course, to quote St Jeremy of Clarkson: "Hybrid? Yeah, in the same way that my Ford GT would be a hybrid if I put a child’s windmill on the roof."

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Plugged in to plug-in

"Toyota has thus far turned its face resolutely away from cars which can store enough electricity to make journeys solely on battery power"

Slightly unfair - the next model of the Prius will be a plugin, and they have already been road testing the development versions:

http://blogs.cars.com/kickingtires/2008/01/prius-plug-in.html

Might be interesting getting one then....

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Some other spanners thrown in the works....

These solar panels will be fixed - they cannot be angled to be perpendicular to the sun (unless you want to add a heck of a lot more drag), so you can forget the additional 2.8MJ (as per Nigel's comment above), you'll barely get half of that.

Then there are shadows from trees and buildings (as well as from our obligatory clouds).

Then there's the additional weight and drag of the panels (probably not so significant but they add up).

All these factors together make me wonder if it is really worth it.

Then there's the fact they are 90% inefficient, that being turned into heat - put one of those on your roof and you'll need more power than the panel will provide to run the air con just to keep the car cool !!!

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@Jeff

That's really quite simple - find out the cost of the panel, and then divide by the cheapest available energy.

Lets assume for a moment that it costs £100 - much less than the cost of a barrel of oil at the moment - therefore the CO2 emissions must be substantially lower than that.

It amazes me how many people think that there might be tons and tons of Carbon used to make a £1 product!

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GS450h 5.9s to 62mph

Jeremy Clarkson was talking bollocks (again) - The hybrid parts add 147KW to the maximum output of 250KW. Although the batteries would not allow this to be sustained for extended periods.

The "solar panel for the Prius" idea has already been done by some companies in the USA.

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Happy

50s technology FTW

I love the fact that a Mini (with an engine designed in the 50s) with £150 of mods is just as economical as a Prius and has a better power to weight ratio.

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Linux

@matt @ Steve Evans

Cooking oil and HM revenue...

According to HMRC.gov.uk you can use 2500 litres for your own consumption in one tax year before you need to declare or pay duty.

http://www.hmrc.gov.uk/si/2007-1640-em.pdf (pdf warning)

You do have to be careful, but not 'cause of seals, but because the viscocity of veg oil (google 'SVO in diesels' ) when cold and the glycerine in it. Older low pressure diesels cope ok with 75%/25% mixes, common rail ones don't! In fact their pumps fail spectacularly with the extra load of thicker oil

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A/C without electricity

Following on from the “it would be nice to run the aircon” theme, why not use a solar powered system to run a cooling system directly, in the same way that a gas-powered fridge works. No heat to electricity to chemical to electricity to motion transducers required, just heat to motion (of the refrigerant).

http://home.howstuffworks.com/refrigerator5.htm

It would only be good as a backup system; no good for de-misting on a rainy day etc.

Just an idea, feel free to build on it or shoot it down.

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IT Angle

My two-penn'th

1) Clarkson-san did a production "costing" on the Prius on the 1st edition of the new Top Gear series (air date 29th June I think) where he advised people about the cost of shipping Nickel (I think it was) from South America to Europe to be turned into batteries, which are then shipped to Japan....very "eco-friendly" in his opinion...!

But then again:

2) Surely any extra "free" energy (such as solar) that can be stored within the car (such as the battery) surely is a GOOD thing....such that over the lifetime of the vehicle, it uses less energy because of the "trickle" from the panels (and not withstanding the production and environmental cost of solar panels in the first place).

Maybe, if more vehicles, such as those with large flat tops, such as London's bendy buses or 40 ft trailers each had solar panels, then overall, all this extra energy could help....?

IT Angle - is there one? (OK - so "solar panels power new generation of in-car GPS" might be one - doh !! )

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five watt panel will complrecharge a marine battery five days"

"five watt panel will completely recharge a deep cycle marine battery in about five days"

Hmmmm

Say battery is 100Ah @ 12V charged by 5W 12V panel

Solar panel will produce maximum 5/12= 0.4A

Time to recharge at max is 100/0.4 = 250 hours

.......or about 10 days assuming bright sunlight 24 hours per day

Bovine extract anyone?

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Anonymous Coward

Eletric vans and trucks

Tanfield have the second most popular eletric motor design. Which is being used by Sainsburys M&S and TNT in the UK. Globally lots of companies use them.

They orginally made eletric milk floats back in the 70's 80's they butt of many a joke, but now they are making Long haul Artic lorries and eletric vans for Ford and Scania, but only for large customers.

This is the future for transport haulage..

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Dead Vulture

classic prius thinking

"fitted onto a car roof (as the Prius ones will reportedly be)" ... that's [onto] not [into] the roof. Has any one bothered to factor in added drag?

The "life of the vehicle" argument makes it [less viable], not [more]. The "life of the solar cell" argument is only very slightly better, presuming you never need the roofrack, the climate improves dramatically and of course assuming you are not involved in anything excessively bumpy or sudden.

However, the Prius is singularly unique in that not only is it inherantly uneconomic in concept, not only is it one of the most environmentally unsound vehicles to construct, not only is it no more efficient than a dirty 20 year old diesel but it is failing to produce on all these levels whilst promoting the destruction of countless perfectly good road vehicles, all in the name of sales. The weak may inherit the Earth, but it is the weakminded who buy into Prius.

"0-62 in less than 6 seconds" as I seem to recall reading above can easily be achieved and is most particularly satisfying to see it done with a Prius... Find a nice cliff, introduce the vehicle to a vertical drop scenario, the further the better. Takes a few seconds to pick up speed then it's down all the way. The most rewarding part has to be the sudden stop at the end.

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How about a Pluggable Electric Vehicles?

In the US there is a grass roots effort shaping up where the mentioned Toyota Prius is modified to actually run on electric for extended periods.

For more details see: http://www.spiritofdc.com

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Go

Re: I know I'm picking nits, but...

@Chris et al. It's the Atkinson cycle engine.

Yes, the Prius is indeed the only production car with that kind of powertrain. None of the other hybrids, hard or soft, have an Atkinson cycle engine. This engine produces more power in a peak, whereas the standard I.C. engine produces power in a wide band. I believe it's something to do with having a longer rest at the top of the first stroke, which allows the explosion to push the cylinder head down right at the beginning of the stroke. Because the power isn't produced in such a "shock", the engine doesn't have to be so armoured, therefore it can be more compact, therefore lighter. Look it up on Wikipedia, because I don't have time.

Just a thought: it would be hilarious to try running a car that size without electrical assistance on just the Atkinson motor. This is why the Insight, with its standard 1.0 liter engine, was so small.

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Boffin

Of course Lexus is just Toyota's posh brand...

.. as any fule do know?

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@Michael N White

Whereas over here in Blighty we've got the Battery Vehicle society who, rather than taking godawful, high-cockometer-rated, clunky designs, and modding them up to very slightly above diesels that are commonly available over here, build electric cars. Doing things properly, y'know?

And not only that, they help each other and talk to each other and foster a community spirit as opposed to scrounging around to pay for someones' roadtrip across America. I mean surely the greenest thing would be to NOT drive across America!?

Even our Kit-Car industry's got in on the act- at Stoneleigh this year on the Mills Extreme Vehicles stand was an MEV R2 fitted with LiFeBatt's LiFePO4 batteries, some control stuff and a NetGain Warp9 motor. 330BHP equivalent, topped out over 100mph, decent accelleration, about £17k (of which 10k was the batteries... you could build it a lot cheaper- though with less range- if you used SLAs) and fantastic accelleration. Only problem was the range of 35 miles- which is still perfectly suitable for driving about town and my commute. And given that a Prius should only be used around town or it's just a heavy, inefficient petrol car, and that they normally carry one person (or it'd overheat from the intense feeling of self satisfaction), it's vastly superior to them. Oh, and no nickel. Lithium, Iron and Phosphates- all, IIRC, available from and sourced from the UK. And they last longer than the Prius.

So to conclude, the UK's doing things properly. You're creating large, heavy vehicles and still cheating by keeping the petrol engine...

flame on.

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Coat

Don't be harsh on the Chris guy.

Y'know, the one who said that a Lexus reaches 0-62 in 3.5″. He didn't specify the speed unit. Although a moderately intelligent reader will automatically assume it's 62 mph (since 62 mph ≈ 100 km/h), I believe that 0-62 km/h is easily achieved in 3.5 sec by a, say, GS450h.

Mine's the one with the conversion tables on its back.

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Happy

clarkson

cause he proved a BMW M3 was more environmentally friendly than a prius - top marks that man

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Waves

For you Prius doubters, are there any other cars manufactured today that get 55 mpg? I sure don't know of any. I get between 50 and 55 mpg every day no matter what speed I average. The only time I ever got less (48 mpg), was traveling through some 12,000 ft mountain passes. The car is very comfortable, with GPS, backup camera, 6 disc cd player, full airbag system, leather, etc. My only criticism is the brakes are a bit touchy. The motor seamlessly kicks in ONLY when needed, and speed has no relevance as some people seem to think. It depends more on the state of the batteries charge and the slope. I have driven many miles, slightly down hill, at highway speeds without the motor ever starting up. If I am driving on even a slight up hill grade, the motor nearly always kicks in. It's no sports car, but I highly recommend this car to everyone. Diesel engines are somewhat efficient, but no where near stoichiometric. My new 2008 Ford F-350 diesel gets 11 mpg. Ouch! So, as far as the added solar panels, if they save one gallon of go juice per day, they probably will be worth their extra cost.

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Re: PR stunt

While I agree with you that the whole car has been a metrosexual PR stunt from the beginning, a rooftop solar is something that will benefit any car. Every car loses some of its battery charge when parked (up to 5-8% a day for some combinations of car+ alarm) and it is recovered during the most inefficient engine operating mode (while cold). A solar on the roof will go a long way towards improving that. In addition to that a solar on the roof coupled with an electric driven aircon can go a long way towards keeping the car environment nice and usable on those +30C days in the middle of a hot parking lot (this used to be an option on the S-class Merc by the way). Once again - savings from having to run the aircon fullblast when the engine is cold. And so on. In fact - it is something that is worth having on any car and not just the Prius.

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Ash
Joke

Isn't this a little like...

... cooking a catering pot of chilli on a 4-ring stove, then holding a Clipper lighter to it?

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@Matt

"To be fair, as far as I can tell modern air-co units take less than 10%."

That was a finger in the air figure, kind of aimed at the Prius, which doesn't have many geegees under the bonnet to start with!

"It's also worth remembering that you can lose 10% in fuel economy while driving with the windows down."

A valid point, although I think you'd need all the windows open to get near 10%, same goes for roof racks.

"You also mention using veg oil etc. Apparently you need to be careful as this can eat the seals in some cars, plus there's the issue of HM Revenue........."

I don't think it eats the seals so much as shifts all the old gunk that has collected there, which has probably been preventing a leak in the first place.

No tax issue with HM Gov any more, personal use, less than 2500 litre (I think) and it doesn't cost you a penny.

"Finally, according to Ford diesel cars are not as efficient for short journeys. I've certainly seen that for myself. Compared to a petrol car the diesel takes an age to get up to temperature and hates short journeys."

Indeed, but for short journeys a bus, your legs or a bicycle would be even better.

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