Solar Hybrid Cars

I have been asked several times why solar panels have not been proposed for charging the batteries in a plug-in hybrid vehicle.  I have not felt that, with current technology, a solar panel could generate enough electricity to provide a meaningful range for a car.  I ran across an article that makes the case for solar hybrid vehicles.  The author assumes that a the car would be driven 10 miles per day on solar power. Additional range could be obtained from the power grid to provide low cost commuting for those commuting a relatively short distance, which is a very large number of people.  The range could be extended considerably by using lightweight construction materials and by future efficiency improvements in solar cells.

According to Cris Neal writing in Energy Pulse "Hybrid vehicles with solar photovoltaic (PV) panels should be part of the solution to America’s environmental problems and dependence on oil." He goes on to say that PV panels added to hybrid cars are much more cost effective than PV panels added to buildings, and that solar hybrid vehicles directly address the shortage of oil. "The incremental cost of solar PV panels on hybrid cars and displacing gasoline has a payback period that is much shorter than the payback for solar PV panels on buildings and displacing electricity.

A solar hybrid vehicle would allow someone to drive their plug-in hybrid vehicle 10 miles to work on grid power. The solar system on the car would charge the battery while sitting in the parking lot all day. Then it could be driven home in the evening on solar power.

His analysis is based on using a vehicle that requires the same power as the Toyota Prius, requiring 1 kWh of electricity to travel seven miles, with a 150 watt solar panel.  A 3.1 year payback period would result when using gasoline at $3.00/US gallon.

Solar Hybrid Vehicles, Cris Neal, Energy Pulse, May 22, 2006

Comments

[The Anonymous Poster]

The rule of thumb for solar panels is assume 5 hours of full sun on a good day. A 150W panel would make 750Wh. This would get the Prius 5.25 miles of driving for a sunny day.

However, one thing you must take into account is that the watt ratings on a solar panel are usually overstated. That 150W panel will probably make less.

[Mel.]

This seems like a pretty good application of the glass-film solar technology that's been discussed at Green Car Congress.

The trick is, of course, creating panels that don't LOOK like panels. But even if solar application is negligible as a mileage-enhancer, these principles seem tailored pretty nicely for powering various onboard electronics such as lights, stereo, etc.

Thoughts?

[The Anonymous Poster]

One other thing. If you're going to put these panels on the car flush with the bodywork, then they will not be at the optimum angle with the sun and produce even less power than it's given rating.

[Robert McLeod]

Silly idea. What happens if you park the thing in the shadow of a building or a tree? Or a parkade or a garage?

Commuting hours are not good solar production hours. Even if you had an hour-long commute in each direction it would still be far more efficient to use a fixed mount oriented towards the sun and actually plug-in the plug-in at home and at work.

[PowerPointSamurai]

I researched solar PV panels recently to charge the trolling motor battery on my boat. The results weren't entirely encouraging. An 18W array is $159.99, or a 15W for $139. Looking at the power-weight ratio of the cells, I'm not so sure its a great tradeoff. They certainly aren't good for steady state use unless you have a purpose-built solar car like the Sunraycer solar race cars. I could maybe buy the argument that if this was purely a commuter car that it could give you a couple of free miles, then it's a pretty good idea. Maybe it could also increase your MPG a little. Bottom line here is that it will save some gas, but don't expect your Prius to go purely solar (unless your house is PV electric and you charge it off your home PV array).

[Jason]

One scenario that solar panels do address is the "Hot car in the sun". A significant amount of energy is wasted in the typical hot vehicle simply by trying to drag the internal temperature back down to ambient.

There are also significant sections around an urban center, where both power outlets and private garages are difficult if not impossible to come by. If you want a PHEV of any flavor, a PVHEV would be your only choice.

For half of my adult life, I've had a vehicle that was driven almost exclusively on the weekend. Five days of trickle-charging in the sun would cover all of my Friday-night and much of my Saturday driving needs.

[hamerhokie]

Not to pile on here, but the Prius can't go seven miles on its battery alone. Were it allowed to discharge down to 20% of its capacity, you might be looking at 4 miles at sub-50 MPH speeds.

[amazingdrx]

Put the panels on the garage or over the parking areas and charge the cars. Even over the highways, or use the solar heat absorbed by highways to generate electricity to charge the cars. and install induction power strips in highways to charge electric vehicles as they drive.

This is a workable use of solar powered transportation. Maybe someday solar cars with the panels on the cars will be practical too.

I would add wind and solar on homes and buildings into the equation too. This distributed generation sand storage, in the electric car batteries is a great solution to our energy problems!

If mass production is encouraged, it will work!

[Stacey Wilson]

Looks like a good solution to the fuel problem. I'm wondering though how much this will cost. If it's going to be costly, then I guess you're better off with Saturn Vue Green Line since it is one of the least expensive hybrids so far.

[bde2200]

I'm so sick of this BS. Anyone who believes in this crap need to put up or shut up. Let's do a little beta testing. You guys put up the money to build this car. Put it on the market. Repeat these claims in your advertising. Then we will see if anyone buys it. Then we will see what your civil and criminal liability is for FRAUD.

Have a nice day.

[bde2201]

Here ya go bde2200...

http://media.ford.com/newsroom/release_display.cfm?release=22296

[bde2202]

School's in. :)

[hamerhokie]

The author attributes zero cost to integrating PV onto a car roof. Yet another assumption favoring his economics.

On the other hand, people place those windshield reflectors on their dashboard every day so it wouldn't be too much to ask them to place a solar recharger on their roof when they park the car. It would be more of an energy appliance than anything, and could be accommodated by a special low wattage DC charging port. When it's time to go, stow it in the trunk or hatch.

You could make one sized at about 300 watts and generate 1.5 KWH easily, maybe more. That would buy you about 7-8 miles in a Prius (modded with a bigger battery for plug-in).

[odograph]

Isn't the charging voltage on a hybrid like 300v? I'm not an electric engineer, but I'd guess that there would be some good efficiency loss as a 12v or 24v solar panel is stepped up that high.

(BTW, I'd put the solar panels on my garage, not my car's roof)

[odograph]

Oh, found this ... maybe you all have seen it:

"The PV Prius uses a 12-volt PV source with a small lead acid battery and battery voltage controller, inverted to 120 VAC, transformed to 345 VAC, then rectified with current control to nominal 300 VDC. The charge from the PV batteries flows into the Prius hybrid battery when the ignition is on.

The 300 VDC output of the solar subsystem is attached to the switched side of the original Prius battery, so the PV battery cannot recharge the NiMH while the ignition is off. The PV system can inject a maximum of up to 2 amps continuously into the battery while the ignition is on.

Lapp’s modelling predicts a 10%–20% fuel efficiency improvement for the 270 watts of PV (to be bumped up to 360 watts with the additional of a fourth panel), so the 10% on the first trip with little optimization was “a pleasant surprise”."

... owning a Prius, I can see +/- 10% as within normal weather (wind) based variation, but for what it's worth:

http://www.greencarcongress.com/2005/08/solarpoweraugme.html

[Sullivan from The Netherlands]

Check tese URL's

www.calcars.org

www.lapprenewables.com/hybrid%20project.html

www.solatecllc.com

[Rob]

I'd like to address the assumption that solar does you more good on a car than on a building. I work in the energy industry and built one of those solar cars once, so bear with me a second.

A solar panel's output varies by the voltage it's supplying - there's a well-known I-V curve for most cells. If you directly connect the panel to a battery, the output is rarely optimized and generally drops off as the battery reaches its full charge. Some systems include MPPT (Maximum power point tracker) modules which can compensate for some of it, but you still drop off on output as the battery nears its charge. Finally, the efficiency of batteries is never 100%. I don't know what today's automotive NiMH batteries are good for, but we used to count on 5% loss on our lead-acids on the solar car. For a car-mounted solar panel, you really only get its full potential when you're on the road driving. One more thought- the peak power trackers go nuts for a few seconds when shadows pass over the car, and you are generally limited by the worst performer in a string. So if you're at a stoplight with wires or a streetlight casting a shadow on one corner of your solar array, that corner sets the performance for the whole array.

Okay, let's consider building-mounted. A building solar installation site is carefully chosen to avoid shadows around the clock and the year. If you have an off-grid system, you have the same limitations for battery storage, but you usually also have some electrical load around the clock.

But, thanks to incentive programs and net metering laws, the cost and availability of grid-tied systems are far more widespread. Most new systems today are grid tied. Here's why - the inverters for net-metered systems generally include the MPPT function within, and the grid is essentially a perfect storage medium because there is always a load out there to accept your excess power. Plus, the grid-tied solar is a big benefit to the grid - it replaces power generated a great distance away by coal, oil or natural gas-burning plants, especially during the hottest days in which the least-efficient peaking plants come on line to support demand. Few people realize how much power can be lost between the power station and your home - up to 10% of the power (sometimes more - check your utility tariff) is lost by passing through hundreds of miles of wire and several trasnformers. The excess power from a grid-tied solar system sometimes doesn't even pass through one transformer - if you and a neighbor are both fed from the same pole, for example, your excess power might travel only the 200 feet to your neighbor's home. The result is that more of the solar power is put to use. In other words, building-mounted solar wins, hands-down.

[Tom Mccarty]

These fellows are marketing an amazing replacement conformal PV roof for the Prius:

http://www.solarelectricalvehicles.com/

Maximum 1200 watt-hours/day, so probably more like 600 watt-hours/day over the course of a year.

In any case, they say it has a payback in 2-3 years, so I'd assume it'd be 4-6 years under the best of conditions. Seems to me that if you live in a sunny climate, and you park in the sun when you go to work, this seems like a good choice.

If this were done on _all_ Prius, the price would probably be more like $1000/car, cheap for 10 miles/day of free power. I wish Detroit actually cared about making useful vehicles like this.

[Gar Lipow]

I think the idea of small amount of integrated solar for peripherals might have some merit in an electric car (not a hybrid) if pv costs come down one whole heck of a lot- especiall for air conditioners. If it could reduce the the peak drain on batteries by reducing air conditioning load in hot sunny weather, it might pay for itself in extending battery life. Very speculative. If solar PV ever becomes cheap enough for mainstream uses, as people say, putting it on the roof of your garage to charge your EV would make much more sense.

[amazingdrx]

Rockin' new nano layer lithium ion battery design that uses titanium oxide. The stuff that makes paint white.

http://amazngdrx.blogharbor.com/blog/_archives/2006/6/6/2009676.html

1 minute charge!

[Jimmy]

MAN! why can't my hybrid (honda civic) have a LARGER BATTERY so I could make more use of it? Driving for more than 1 minute on the battery alone at sub-30 mph speeds drains anywhere from 1/4 to 1/2 of the battery. BTW... i like the post above mine

[satyanarayan prasad]

i want a proper size ,solar panel to ,touse it in my hybrid electric vehicle

[thebizofknowledge]

The only problem I see with this is that the average consumer drives more than 10 miles to work, and also the trip involves side trips to pick up kids from school and daycare, as well as running errands. It seems to me the range would have to be increased somewhat for this to become a viable option.

[Mike Tieman]

HYBRID AUTO'S SOON OBSOLETE?
"rev the engine up to 300 RPM and take off"

Las Vegas, NV September 28th ...... In two days, the local manufacture of the OmniValve automobile intake valve, brings to the floor of the SEMA show, what they say "will make hybrid's obsolete" their latest version of the OmniValve. The new design has higher lift and is designed to go the distance 100,000 miles or more.

Hybrid technology uses electricity generated by the engine to do the low speed driving in the city with lots of starts and stops. Electric motors can generate very large amounts of torque efficiently to get your car moving. This is where Internal Combustion engines are the most inefficient. Using this arrangement, hybrid cars today get city mileage greater then they do highway mileage. However with the cost of gasoline in decline so are sales of these hybrid autos. Saving money owning a hybrid, even with $3.00 a gallon gasoline, which was with us just a few months ago, is not a guarantee. The auto itself is much more expensive and the batteries are quite expensive to replace. The life span of the batteries varies but if your not careful you could be buying 3000 dollars worth of batteries after just 3 years of using the car. That is 1000 gallons of gasoline, more then offsetting any fuel savings. So, the hybrids future is unclear at this point, so says OmniValves of Las Vegas.

OmniValves say there is a better solution, if you use there patented intake valve, you can create the low end torque similar to that of an electric motor for your autos city driving needs. This would do away with the need for an electric motor and more importantly the batteries.

An OmniValve V-8 engine can idle at 200 RPM, creating enough torque to run the A/C the Alternator, water pump and the power steering, then just rev the engine up to 300 RPM and take off. This is a significant improvement in low end torque. It is basically unheard of for a cars engine to idle at 200 RPM. For example a hybrid car would normally idle at 700 RPM. OmniValves also say that an auto with their technology generates far less pollution than a hybrid. The amount of, heavy metals like Lead and Zinc that is used in making and running Hybrid's makes it not very environmentally friendly, says OmniValves.

OmniValves say they will save the most precious resource there is ..................... Money! Saving money is the same as saving the environment, according to OmniValves. "While the Hybrid cost is up to $15,000.00 more then a conventional car of the same size and style, the auto that uses the OmniValve is about $150.00 more, which will be saved in about 3 months of driving" says OmniValves.

"Then you have the savings in R&D and tooling to make these new hybrid models, your talking 100s of millions saved and passed on to the consumer, it is a win, win scenario" says OmniValves.

OmniValve is so satisfied from their testing and that there is no doubt what so ever this technology works and works extremely well and they are so comfortable with their broad patents and patents pending, that they are offering to engineers, manufactures and even some individuals, free sets of the OmniValve. To qualify for a free set, you must be either a potential customer or someone who can advance the technology or someone willing to do advanced testing. Further details can be seen at www.omnivalves.com or Booth 51008 at 2006 SEMA in Las Vegas The Valves can be seen in person also in the Grand Ballroom New Products Showroom.

[Paul Emus]

I use solar panels in my car windows to power small fans in cracks of the windows to keep the interior cooler. I have an Igloo ice chest type cooler that cools with a 12 volt plug, but one big solar panel I have does not seem to run it yet. I also have a small AA battery charger with solar panel. There might be other possibilities.

[scott]

here's a solution to keeping your car cool in summer months using solar power.

http://www.audi.com/audi/com/en2/tools/glossary/operation_comfort/solar_sunroof.html

[Hybrid Car Owner]

Interesting discussion, obviously the solar powered hybrid is still years away from a reality.

[Dr. Al]

I have designed just such a car. See http://www.physicslablh.com/futureDesign.htm

[Clee]

Al, I'm wondering why I don't see any photovoltaic cells in any of your artsy sketches. How many square meters of PV did you design in?