JUN 03

None of that sounds legitimate. Their website is far too thin on testable/analyzable specifics. Even if that PV had optimum angle towards the sun at all times, unobstructed and outdoors, it would get only about 4 hours of insolation on an average day in an average city. That's good for 848 watt-hours. Again, that's if the panel were able to track the sun, which it can't. So let's be generous and say it can get 750 Wh/day.

A Prius used 250 Wh/mile, so that solar charging is good for 3 miles/day.

A typical new vehicle will be used for 15,000 miles/yr, or around 41 miles per day. Real-world Prius MPG is 47.5. Run the numbers, and that means this would save - again, being generous with the sunlight assumptions - 23 gallons of gasoline per year. That's worth $75 at current gas prices.

Take their lowball price estimate of $2,000 (which seems impossible, but let's go with it), and you're looking at a 27 year/405,000 mile payback period.

By comparison, say you had a green power option at home from your utility. Current net premiums are around 1 cent per kWh, with the national average for residential electricity at 9.96 cents per kWh. So that puts utility wind to residential customers at around 11 cents per kWh.

The 48V DC battery in this company's setup has a 3 kWh capacity (62.5 amps) with a 95% charging efficiency. So to recharge it from a completely discharged state takes 3.16 kWh. At 11 cents per kWh, that comes to 34.6 cents for enough energy to move the vehicle 12 miles.

Assume full discharge and recharge daily, and ignore battery replacement costs for the moment. Keep in mind that the solar panel plus installation is at least $1,000, if not more, so taking their lowball price estimate of $2,000 (which again, is probably unrealistic), then the net cost would be $1,000.

Run the numbers, and the payback period for that approach is under 6 years, or around 85,000 miles -- less than 1/4 that of the solar arrangement.

U wonder if the this voids the warranty ?

It works and you guys are guessing if you'd just read our year old white paper on the web site you'd be close. We have moved on to a high voltage batteries replacing the factory unit with proven techonogly and been driving around for the last year on solar power in my Pruis. I think the gas has gone bad at this point. At $ 4 a gallon this is a simple choice keep hidding under a rock and prey for more oil or move on to a new world. I can't keep up with the orders.

It works and you guys are guessing if you'd just read our year old white paper on the web site you'd be close.

With all due respect, Greg, that's hardly a "white paper". I read everything on your website before commenting. You lowball the electricity consumption of the Prius by a substantial amount (it's usually estimated at 250 Wh/mile and you claim it's between 150-175 Wh/mile). You also assume a "a nominal daily trip length of 28 miles", which is not the proper nomenclature. What you mean to call it is "vehicle miles traveled" (VMT). A "trip" is a single "A to B" journey. Most vehicles take several trips per day. Reagrdless, the average VMT for a newish vehicle is not around 10,200 miles per year (per your estimate), it's between 14,000-16,000 miles.

As for the amount of energy one would expect to get, your numbers assume insolation values between 4.16 and 6.36 (212 watts w/95% conversion efficiency through the charger), and that's if the PVs were optimally oriented, which certainly wouldn't be the case with a vehicle that could be inside, under a tree, etc, but always has a fixed plate pointing directly up. Those values themselves are skewed towards the kind of average numbers one sees in sunnier climes, and certainly are not typical of what one would see during winter months. So the variation in insolation values are much wider than the range you gave and certainly need to account for the fact that the panels don't track the sun and keep an optimal angle (and again, might not even get solar exposure many times). And if you're assuming the car is always out in full sun, you'd need to account for what that will do to the paint and surface of the vehicle compared to keeping it garaged most times.

The PVs themselves are rated above average efficiencies, so they must come at a premium. Either way, the peak watt average price runs $4.85 right now, so the PV alone should cost $1,028. Since it's a custom design, I can only assume it costs more than that.

You then go on to play with the assumption (rightly so) that the real-world mileage of the Prius is not going to be 55 but closer to 45. Data seem to indicate it's 46-48 mpg. Regardless, you use this lower fuel economy number to update your financial model without an equal adjustment in the Wh/mile numbers (since those wouldn't be the same between theory and real world, either).

You then go on to say that combusting 1 gallon of gasoline puts 24 pounds of CO2 into the atmosphere, when actually it puts 19.564 pounds per gallon.

You then go on to posit that a "PV Prius" could run totally on solar by connecting up with a home solar array and upping the battery pack to 8 kWh size. Assuming the 50% discharge in your model, that means 4 kWh would be available per day. Again, you would need a battery much larger than that, since it's really more like 250 Wh/mile with 41 VMTs per day. And that's an average amount, so it's unlikely one will never exceed that amount, hence it will never be "purely solar" unless you propose increasing the battery pack size up to that of a full BEV -- and even then. Tesla only claims 200 mile range for their vehicle, and that's with about 200 Wh/mile at the outlet and a massive LiOn battery pack. But even at 41 VMTs/day @ 250 Wh/mile, assuming your 50% discharge level, that's going to require a 21.5 kWh battery pack. Would something like that even be feasible if it's lead acid?

At $ 4 a gallon this is a simple choice keep hidding under a rock and prey for more oil or move on to a new world. I can't keep up with the orders.

First of all, gas isn't $4/gallon. It's $3.16 and falling. The fact that oil prices are high and that are environmental consequences does not mean that your specific type of solution is cost-effective, or even the best option for increasing the efficiency of a Prius. Saying "you can't keep up with the orders" without customer testimony, data on sales, or any sort of concrete data on performance and actual, real economics (not theoretical ones), makes much of it questionable. And almost all of the empirical assumptions of your model are favorable to you, so when combined, they completely overstate what someone may likely achieve with this setup. You don't even have concrete prices for systems on your website, nor any mention what these mods will do to one's manufacturer's warranty.

It would be great if this all worked out, but my experience with renewables, their economics, as well as hybrids and their economics, just doesn't make this wash for me. You'd need to have a lot more concrete, verifiable performance and economic data for this to be more credible.

While I agree with the above analysical methodology, it fails to account for the full cost of gasoline, which is NOT $3.16/gallon. You should use the life cycle cost of gasoline...including costs of environmental damages (Exxon still has not paid for the Valdez accident...), maybe even the war in Iraq and Nigeria, etc., etc., that are not reflected in the pump price. When you can account for the actual cost of a gallon of gasoline vs. the lifecycle cost of PVs, then I will accept your arguments. PV technology has been supplemented by huge government investments, but those amounts are a fraction of what the US has invested to support the oil industry (e.g., $700B in Iraq since 2003). Until you account for gasoline's life cycle costs, you are only cherry-picking cost factors to suit your arguments. Unfortunately, this methodology is in widespread practice by industry-supported propaganda groups intent on subverting the US and world democracies for short-term corporate profits.

While I agree with the above analysical methodology, it fails to account for the full cost of gasoline, which is NOT $3.16/gallon. You should use the life cycle cost of gasoline...including costs of environmental damages (Exxon still has not paid for the Valdez accident...), maybe even the war in Iraq and Nigeria, etc., etc., that are not reflected in the pump price.

That's neither here nor there. No individual controls the subsidization of petroleum, to whatever extent it exists, so it has no relationship to the personal financial balance of this "solar prius" proposition put out by this specific firm in its specific way.

..to real geeks that are concerned for the ecosystem. i thought the whole point of this website was to pool our efforts as a community to give the world hope as far putting our brains together and coming up with an answer. everyone here who's whined about this solar car possibility isnt exactly setting the standard on public effort, let alone taking time to come up with their own plan of action for environmental support, right?

lets see.... ALL OF YOU whiny babies that crunched numbers and memorized statistics...aside from probably still being virgins...have you tried to solve our pollution problem lately? have you even purchased anything that helps your life lean towards green? participated in anything that informs the public about going solar? no? i didn't think so.

if your idea of helping is posting on blogs about what you THINK is other people's faults, then thats quite the opposite intent of this whole eco movement. so do us concerned citizens a favor...next time you feel like contributing to the global cause, be sure to wear a condom if you EVER engage in intercourse. stopping the spread of your seeds is a greater action for the world than you might think.

thanks kids!

Uncle Ken :)

everyone here who's whined about this solar car possibility isnt exactly setting the standard on public effort, let alone taking time to come up with their own plan of action for environmental support, right?

Wrong.

aside from probably still being virgins...

Are you twelve?

have you tried to solve our pollution problem lately?

Yep. Been working on it for a long time. That's how I can smell fanciful nonsense a mile away.

have you even purchased anything that helps your life lean towards green?

Care to come to my home and see?

participated in anything that informs the public about going solar?

Made my own thermal panel when I was a 5th grader about 30 years ago. Started there.

no? i didn't think so.

Then you think wrong.

if your idea of helping is posting on blogs about what you THINK is other people's faults, then thats quite the opposite intent of this whole eco movement.

First of all, that's hilariously ironic, since that's precisely what you're doing. Secondly, I didn't post about someone else's personal faults, I analyzed a product claim. Are you able to distinguish one from another? Is this infantile ranting of yours the only means you can address the actual topic of this thread? Why are you unable and/or unwilling to challenge my position on the topic? Oh right, because then you couldn't launch into some misconceived moral superiority tirade.

so do us concerned citizens a favor...next time you feel like contributing to the global cause, be sure to wear a condom if you EVER engage in intercourse. stopping the spread of your seeds is a greater action for the world than you might think.

Wow, that's a really effective and on-target comment. Happy to get all that foolishness off your chest?

Thanks so much for your contribution to the betterment of the world with that post.

if ken is 12 or not, hes funny. me likey a lot! eat poo jim. nah nah nah nahhhhhh!!!! you stinky!!! this bloggy lame-o. jim eats poo poo. ;D

Juvenile trolling as a response is always the best indicator of the solidity of your argument.

Jim,

Why don't you take your own advice and go see Greg Johanson and his Prius. It sounds like he has at least a years worth of proof he could show you. Calculations on paper don't prove anything except that you know how to do calculations. Go out into the real world and look at the proof, if it exists and then let us know what you find. EPA calculations show that my 2004 Mazda 6 Sport Wagon should only get 27 MPG highway. I have kept a record of every gallon of gas I have put in the car and can show a real world 32.8 MPG best tank average to date. Every tank averages better than 31 MPG.

Why don't you take your own advice and go see Greg Johanson and his Prius.

Why would I do that? I should fly out to somewhere every time someone proposes an idea which doesn't float? He can provide solid data and no one needs to go anywhere.

It sounds like he has at least a years worth of proof he could show you.

What's keeping him from posting it on his website for others to analyze?

Calculations on paper don't prove anything except that you know how to do calculations.

That's a good one. You're basically invalidating all of natural science with that comment.

Go out into the real world and look at the proof, if it exists and then let us know what you find.

Another silly comment. He can easily provide all the technical and financial information that anyone could analyze.

EPA calculations show that my 2004 Mazda 6 Sport Wagon should only get 27 MPG highway. I have kept a record of every gallon of gas I have put in the car and can show a real world 32.8 MPG best tank average to date. Every tank averages better than 31 MPG.

Bully for you.

http://www.fueleconomy.gov/feg/why_differ.shtml

That's a good one. You're basically invalidating all of natural science with that comment.

Natural science frequently invalidates many calculations but this is the exact response I was expecting from someone who knows everything and only believes himself. Thank God most of the creative people in this word are not like you or we would still be living in caves.

Natural science frequently invalidates many calculations but this is the exact response I was expecting from someone who knows everything and only believes himself. Thank God most of the creative people in this word are not like you or we would still be living in caves.

More content-free ad hominem from you. Yawn.

Natural science frequently invalidates many calculations but this is the exact response I was expecting from someone who knows everything and only believes himself. Thank God most of the creative people in this word are not like you or we would still be living in caves.

That's lovely. The fact that some people are successful with their creativity does not validate some random snake oil.

You know nothing about me, but that isn't the point of your whiny comment. Bye.

I think that solar energy is the best alternative energy source there is. If its possible to make this technology cheaper, then why not use it for all cars?