[heypete]

Hey all,

I'm a proud new owner of an '03 Insight (53 miles on it right now, whoo!), and I had an idea that I'm curious if anyone else has considered.

During the day, my Insight sits out in a parking lot in direct sunlight doing absolutely nothing (while I toil away at work). Usually the IMA batteries are about 2/3-3/4 of the way full. Since I rarely load cargo into the hatch, it would seem to be a prime area to put a solar panel on the cargo deck, and have it somehow wired to the IMA batteries, so as to trickle-charge them when the vehicle is not in use.

Has anyone else thought of this, or attempted it? Any advice?

Cheers!

 

[Armin]

dead horse

Hi, Pete,

this has been discussed many times. The short answer: nice idea but impractical and not economic.

The slightly longer answer: the amount of energy you could potentially reclaim with a solar cell even in a full day of sun is negligible compared to the capacity of the battery pack. Add to that the difficult voltage transformation from a solar panel (<=24V) to the batteries 144V. Then you'd need to find a way to do this without upsetting Hondas addmittedly mediocre battery management. Plus, you'd have to put the cells on the roof, not inside the car. Most of the energy of the sunlight would be lost in the glass.

 

[Thorian]

However you could place a solar coker on the back deck and cook your dinner while toiling away at your desk. I already leave a can of ravioli or like wise ready to eat can good there for a nice hot lunch

 

[Aaron Cake]

However you could place a solar coker on the back deck and cook your dinner while toiling away at your desk. I already leave a can of ravioli or like wise ready to eat can good there for a nice hot lunch

Ya know, that's actually a very good idea...

 

[jameskb]

However you could place a solar coker on the back deck and cook your dinner while toiling away at your desk. I already leave a can of ravioli or like wise ready to eat can good there for a nice hot lunch

I second that experience: I've left cooked chicken out for about an hour and find it to be nice and hot for lunch. Pick a precooked food with lots of preservatives or salts to protect you against bacterial growth. I've had good luck with precooked chicken or pork, and vegetables in sauce in a "glad container". Always put something underneath the product to catch it in case the container ruptures and leaks.

 

[jameskb]

During the day, my Insight sits out in a parking lot in direct sunlight doing ... it would seem to be a prime area to put a solar panel on the cargo deck, and have it somehow wired to the IMA batteries, so as to trickle-charge them when the vehicle is not in use. Any advice?

Pete;
It's an interesting idea that's been used before. I'm thinking about the all-electric Fiero a few years back with all the horizontal body surfaces covered in solar cells. They'd done an awsome job integrating the cells into the body contours. Expensive car because of all that body work.

I think your solar panel idea is worthwhile even if it only gathered you an extra "few bars". My thinking wasn't so much to harvest energy, but to provide the 144V cell with a very soft recharge during the day. I have a commute that ends and begins daily in a metropolitan area. So when I arrive at work, I've got low charge and the same holds true when I depart. I have a nice long highway drive to charge the cells, but they spend most of the day discharged when they could be using some of that solar energy.

Too bad the Honda designers didn't build the 144v-12v charging circuit to work both ways, not too hard to do and wouldn't cost much. Then you could get one of those 12V dashboard panels and just plug into the 12v power point.

Your thought about putting the cells in the back cargo area is good: it saves the need to drill somewhere to pass wiring into the battery, plus, that puts the cells right on top of the 144V module. Short wiring would really help.

Two problems to think about. First, it renders your cargo area hard to use for anything else. This could be helped by a panel that could fold up like an accordion. Second is heat gain. The dark solar cells will enhance interior heat gain and solar cells lose a couple percent efficiency when they get hot.

What kind of power gain? Say you've got a 50W panel. Probably about 4A at 12V. You could up-convert that to 144V at about 1/3rd amp. Not a bad charge rate for, say, 6 hours conservatively. Might get you "a few bars" with the 300-400 Watt-hrs you'd gain during the day. You'd need an EE buddy who knows how to build a "charge pump" to do the up-convert. You could also do it with one of these DC-to-AC upconverters, but you start getting into lesser efficiency with that scheme.

My big unknown is, how does the computer behave when the pack mysteriously gains charge in those six hours. Does it recalibrate every time the car is turned on? If so, then it wouldn't be a problem. But if the computer expects charge to come only from the motor, then you could end up with some overcharge. I'm just not sure how the Honda engineers designed the computer to think....

Good idea, though. Keep chewing on it and asking around.

 

[Will M]

Too bad the Honda designers didn't build the 144v-12v charging circuit to work both ways, not too hard to do and wouldn't cost much. Then you could get one of those 12V dashboard panels and just plug into the 12v power point.

I love appropriate technology. That's why I love the Insight. The dark side of that is that I have an inappropriately passionate response to technological ideas that I honestly believe are not well thought out.

I want to be concise here, so as not to annoy people more than necessary. First, the Insight obviously works well without solar panels. Before a company could justify paying the money to develop a solar electric charger for the Insight, they'd have to see a sufficient benefit.

I like solar power. I've lived with it and am building a woodworking shop that will be powered by it. Having a stable site, clear of trees and buildings is possible for the shop, but not for a car. The building doesn't care if the panels are not aerodynamic. Flat, non-aerodynamic panels are already expensive. Making them integrated into the Insight's sleek body would be quite expensive.

Given those basic problems, the idea is already too impractical to then have to think about voltage levels, SOC calculations, the inefficient angle of the panels to sunlight in a parked car, and the simple fact that there isn't enough surface area on an Insight to collect enough solar electricity to improve the performance of a car that is already doing just fine without the panels, especially considering the remarkable cost of such a system.

It's really easy to pull out a paper napkin, draw an Insight and put some panels on it, labeling them and then talk the idea up to other people who are clueless as to the impracticality of the idea. It's really hard to make the idea work at all, even if you don't consider the cost, and in the real world, engineers have to consider the cost.

Your thought about putting the cells in the back cargo area is good: it saves the need to drill somewhere to pass wiring into the battery, plus, that puts the cells right on top of the 144V module. Short wiring would really help.

You are ignoring the rather dramatic loss of solar-electric power you get when sunlight goes through the glass of the rear window. Hold your hand out in the sunlight and notice the color and brightness of your skin. Now partially hold open the tailgate and look at your hand illuminated through the rear window. The tint is darker and there are all those little shadows of the defroster lines. In terms of solar electric production, this is a big deal. It wouldn't work. Most sunlight on panels is consumed bringing the voltage up to that of the system you are attempting to charge. It is only the brightest, most direct exposure to the sun that pushes the panel up high enough to charge the system. You can't afford the loss of going through that rear window.

Two problems to think about. First, it renders your cargo area hard to use for anything else. This could be helped by a panel that could fold up like an accordion.

At this point, you are either talking about a panel that produces so little power that it is a joke, or you are talking one that is so expensive that it is a joke.

Second is heat gain. The dark solar cells will enhance interior heat gain and solar cells lose a couple percent efficiency when they get hot.

Your calculations here are focussing on a few small details while ignoring factors much greater than a couple of percent efficiency. You'll lose much more than that just going through the back window. Then there are tracking issues. You have to aim the panels fairly directly at the Sun and hope that the shadow from the edge of the window doesn't cover any of your cells.

What kind of power gain? Say you've got a 50W panel.

Do you actually know of a 50W panel that is small enough to fit in a Honda Insight trunk and be fully illuminated, without shadow? I honestly didn't know that such a panel exists. I find it startling how much more efficient that panels have become since I bought my 75-watt panels that are quite a bit too long to fit in the trunk without being well in shadow, even at noon in summer. I think they are about 4' long and a foot and a half wide, though that's from memory.

Probably about 4A at 12V. You could up-convert that to 144V at about 1/3rd amp. Not a bad charge rate for, say, 6 hours conservatively.

The engineer who helped me design my solar electric system explained that I should plan on a maximum 4 hour solar day. Without an active solar-tracking system aiming the panels directly at the Sun, this is what you can expect, given that the panels are pointed at one spot and most of the time the solar angle is too poor to generate significant power. Add clouds part of the time. It's a good solar day if you collect the amp hours you'd get from 4 hours at the rated output of the panel. This assumes that the one spot you aim the panels is well chosen. In a car in a parking lot, it won't be.

Might get you "a few bars" with the 300-400 Watt-hrs you'd gain during the day.

I think your math is startlingly optimistic. It also doesn't include any talk of cost. I honestly believe that you'd spend a bunch of money, risk screwing up a remarkable car and not get anything close to a benefit from it at all.

 

[IamIan]

Solar Insight

I love technology as well. Especialy the science behind it. javascript:emoticon(':lol:')
Laughing

The Solar Cell insight can work.. but I agree it is more than you think.
And unless you just have money to blow on it .. generally not worth it.
javascript:emoticon('')
Sad

I was looking into buying an all electric car or converting the 1990 chavalier I already have to electric. There are serval companies in the US who do make Electric Cars Or who Will convert for you or help you convert a car to electric but at $5,000 to do the conversion yourself or $12,000 + to have someone do it for you That is steep when you think that a conversion car only gets like 50 miles per charge and about 60 Mph top speed unless you want to dump some serious money into the project and there are people in the U.S. who have gotten cars to over 100 Miles on a charge and in the same car are pushing over 150 Mph but these people have everything custom made and generally wont' even talk about the costs becuase they didnt' care... I do care about the costs.

I Found a 2000 Insight for About $12k I choose that over the complete electric for range issues and for support actually becuase the insight I can take to honda dealers an electric car you are pretty much doing all the work yourself.

Anyway the issue at hand... When i was looking into the electric car options I contacted some of the places that do the conversion for you and some of the people who have web sites that they did the conversions themselves. With a Big Flat Solar Pannel Added you Would Generate an Average of About 5 Miles per day worth of Electricity in A Pure Electric Vehicle (EV) But unless it is a custom made body you completely destroy the arodynamics to do so. Now the Insight is not Pure EV so the Power would serve to help the car and it is lighter thanks to alluminum than most other cars so in those ways you would do better ( Infact there are 2 insights that i know of in the US that have been converted to pure EV ) but the arodynamics would kill your MPG in a standard insight ... that is unless you got the flexable solar cells which they do make... these would be able to bend around the contours of the car and if done right shouldn't effect the arodynamics anymore than a car bra would.... but before you start thinking that this is a sollution you just got more problems... Flexable solar cells are about 1/2 as effecient which means 1/2 the power of the ridged silicon cells under the same conditions and cost about 3 times as much. And once you start following the contours of the vehicle as stated in some other posts from other people you get shade and loose the direct sun light effect.... which if you look into house solar cells which i have also been doing can have a major impact from what i have read so far a Car would with the flexable solar cells shaped to its contours would loose at least 20% of the sollar cells maximum power output on the top of the vehicle and at least 60% on the sides of the vehicle.

Ok So Lets look at this ... Flat solar cells at best convert about 12% of the light to electricity If you use the flexable you might get about 5% of the light into electricity of which you loose 20% on top due to the light not hiting it at the correct angle and loose at least 60% on the sides but with the small size of the insight you shouldn't end up with any more surface area than say the GM Sunracer which was a pure solar designed car from start to finish.... so at best you might if your lucky and it is sunny get about 1 Mile worth of Electricity per day from such a project.???? Is that worth it???? I say probably not... Especcaily at triple the cost of flat solar cells which are already very expensive. As anyone who has done a solar house project will tell you.

FYI.... There is one guy do put the cost to no opption and bought an insight just to gut it to make an EV he says that the final project once he is done will be great gettign like over 200 Miles on a charge and going with a 20% torque boost from the standard insight but he won't even comment on the cost he dumped into it. Even he doesn't think it is worth the cost to put solar cells on it.

:lol: