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Thinking of a solar panel for your Honda Civic Hybrid ? Here's the why and the how. (http://www.cleanmpg.com/forums/showthread.php?t=10872)

http://www.cleanmpg.com/photos/data/500/HCH2SP_NewsImage.JPGManuel Santos - CleanMPG (http://www.cleanmpg.com) - May 8, 2008

Introduction

As many of you have noticed, the arrival of summer seems to spark renewed interest in all sorts of “Sun” related activities and gadgets. One of these is solar panels for automotive applications … and for good reason not only because we always wonder about what else is all that radiated solar goodness good for but also because there's something fascinating about having a solar panel installed in a car – call it the “wouldn’t it be cool to have that” factor.

Still it is mostly due to the overwhelming number of requests that I’ve had that I decided to produce this somewhat more detailed step-by-step guide of how to install a small solar panel on your second generation Honda Civic Hybrid. Of course, many of the steps illustrated in this guide may be applicable to many other vehicles particularly the first generation Civic Hybrid but despite any potential similarities, I offer no explicit guarantees that these alternate installations will parallel the exhibits in this guide.

Also, many of you are eager to know what an install like this actually does for your fuel economy and in truth I say that it totally depends on the circumstances. For some folks this mod may offer little or no benefit, and for others (such as myself) this is likely to be a pretty effective “must have“ option.

What this modification does

Like in the first article, the objective of this mod is to install a solar panel to charge and supplement the 12V power losses on the HCH-II. As in the previous article, it makes sense to repeat that this solar panel installation does not charge your hybrid's battery pack.

Then, what are the benefits, and why?

True to Honda's design philosophy of "man maximum, machine minimum", the HCH-II has a power management system that is best described as a design of optimal minimums. The consequence of such a design is that very little "electric headroom" is available for accessories with larger power signatures without these having a measurable impact on the average fuel economy. To put it mildly, the small 12V battery is hardly able to sustain the power demands of anything else beyond the OEM equipment already in the vehicle.

Now, add one or more after-market systems (i.e: Audio, alarms, corrosion inhibitors, air pressure pump, etc) and this headroom is not only gone but we are now operating in a slight power deficit. To make matters worse for some folks, add 4-6 months worth of below freezing temperatures and you will no doubt see a good chance for trouble.

At its worst, the 12V accessories battery life will be shortened due to it running at a less than ideal charge level for extended periods of time. At best, you may have an IMA crash or a chronic dip in your fuel economy.

The idea behind this project is that any “solar charge” you get into the 12V battery (especially when the car is parked in a bright day) will not be diverted from the IMA system when the car is running. In traditional vehicles this is not as severe a concern since the 12V battery charge is obtained directly from the alternator with minimal downstream losses due to energy conversions. On many hybrids such as the HCH, the 12V battery charge is obtained from the DC-DC converter, which it in turn often gets the "energy" from the traction battery. While it may appear that this process is not much different from that of a traditional vehicle, the fact is that on the HCH, the energy that arrives to the 12V has already been subjected to many more energy conversion losses and therefore arrives to the 12V battery with a higher cost premium.

The following diagrams provide a very rough idea of what is truly happening and why the 12V charge is more costly for the Civic Hybrid strictly on the basis of watt-hours.

http://www.cleanmpg.com/photos/data/522/HCH2SP_DiagramRegularCivic.JPG

http://www.cleanmpg.com/photos/data/522/HCH2SP_DiagramHybridCivic.JPG

As implied by the above diagrams, the energy conversion losses are measurably higher in the Civic Hybrid particularly when it comes to charging the 12V accessories battery. This is because the 12V subsystem is much further downstream than the energy path of a traditional car. Also by implication, this means that more kinetic energy (hence fuel) is required in order to generate similar amounts of electrical energy to power the vehicle’s accessories. How much more? It certainly depends on the actual 12V loads... but also on ambient temperature, the amount of time a vehicle is driven per day, driving conditions and other smaller factors.

Sure, the solar panel does not produce that much current to help the vehicle while it is in motion, but over the course of several hours of exposure while stationary in a sunny parking lot, it begins to make a small and measurable difference. Over the long haul these small differences *can* become significant in more ways than one.

Just for giggles: "What is the gasoline equivalent of the energy provided by this solar panel?"

This is where things can get a little complicated. Using a regular gas only Civic as an example, we can arrive to an estimate of this energy with the following approach:

Solar Panel energy calculations:The nominal energy provided by this solar panel over an 11 hour day: Power: 130 x 17.5 = 2.275
Energy: 2.275 x 11 x 3600 = 90.090 KJ

A liter of gas has approximately 32 Mega-Joules of effective energy (less if blended) and that means that running the solar panel will net you the equivalent energy contained in 2.8ml of gas. Then also assuming that the regular Civic engine has an efficiency of 25% we find that it takes 11.2 ml of gas to generate the equivalent energy provided by the solar panel. That is roughly equivalent to 2.4 tea spoons of gasoline saved in every liter of gasoline used...

Is this a lot? No, definitely not in the case of the regular Civic.

Things don't look significantly better for the Civic Hybrid either. This is assuming that it can travel further than the regular Civic on the same amount of fuel... and perhaps in the hands of an attentive hybrid owner we're probably talking twice the distance? Despite the added gas engine efficiency of the HCH over the non-hybrids (up to 6-10%), the HCH is further burdened by downstream energy losses mainly due to the 12V subsystem which are estimated to be at best 40-50%. So we would save at most 5 tea spoons of gas. Hummm...

Definitely not a big case from the fuel efficiency angle either. However, things are not as simple as they may appear either.

For example, what is the benefit to FE if with this mod I can avoid or reduce the chance of an IMA forced regeneration by making it easier to maintain and manage the SoC? What is that worth to me? What about the 12V battery life? What if it can prolong its life by a year or two (perhaps more?) by having it always topped off?

In any case, if you like the extra edge on your side and you don't mind the "novelty" aspect of it then this mod may be for you too ;)

A common question:"Why not do the same to charge the traction battery (the NiMH battery pack)?"

Although a good idea, it is still betrayed by three simple constraints:Cost, safety, warranty

Yes, it will likely be done someday once somebody designs an affordable cooperative charging system that is both effective and safe but one thing is certain regarding the OEM warranty: such a modification/enhancement will definitely void it for sure.

Some words of CAUTION before we begin

As usual, I cannot take responsibility for anything that may go wrong if you attempt this mod on your own. If you feel like this may be over your head then you’ll do well giving the job to a car audio shop or a skilled friend. And always keep in mind that even if you succeed in getting the setup to work, it should look professional enough to withstand the scrutiny of Honda technicians should you ever need to take the car in for any kind of warranty work! Also, remember that the system must be easy to disconnect upon request from a technician or service department. In other words consider the examples and steps illustrated in this guide as the minimal specification of your install and if you EVER deviate from this example then do so to make it better and more robust.

Step by Step

First and foremost, let’s introduce the solar panel that we will be using in this install. By the way, I purchased quite a few of these panels which over the next few weeks will find their way into 4 different HCH-2’s and one 2007 Prius, so I expect this installation process to remain relatively unchanged. I will update this article if I encounter any additional optimizations worth mentioning.

http://www.cleanmpg.com/photos/data/522/thumbs/2_4WSolarPanelPkg1.jpghttp://www.cleanmpg.com/photos/data/522/thumbs/2_4WSolarPanelPkg2.jpghttp://www.cleanmpg.com/photos/data/522/HCH2SP_SolarPanelMountedOutsideView.JPG

What it looks like when mounted

This particular panel produces a maximum power output of 2.4 watts and its nominal operating specifications identify the voltage at 17.5 volts and the current at 130mA. Yes, the voltage is significantly higher than the 12V level the HCH-2 battery is rated for, but the load of the battery and the other “always on” devices on the system bring it all back down to the nominal 12V level. So, there’s really nothing to worry about here.

Why not use a larger panel? Well, the truth is that a 5W or larger panel will likely overcharge the tiny 12 volt battery and may require a charge controller to keep things safe. Since a charge controller costs in the vicinity of $40 many may find a 5 watt or larger panel too expensive and overkill for this application.

In this exercise we will be installing this panel on the rear dash as illustrated in the following picture. To do this we will need to drill a little “pass-through” hole (the smallest possible) on the trim into the trunk area. To accomplish this I used a 5mm drill bit and I gently drilled the hole upwards from the trunk. One thing I noticed is that there’s a “wool like” white lining underneath the trim that may need to be parted before spinning the drill bit through. Otherwise, you could risk bunching it all and reducing the benefits of the inner lining.

http://www.cleanmpg.com/photos/data/522/HCH2SP_RearDashEmpty.JPG http://www.cleanmpg.com/photos/data/522/HCH2SP_TrunkPreWiring.JPG

Use a 5mm drill or smaller to create a pass through hole for the solar panel wire

Now, before we do any more work we need to prep the solar panel for installation. If you notice, the panel’s wire exits through one of the sides horizontally. Personally I find this protrusion aesthetically unpleasant so my objective is to do away with this by opening the solar panel and finding another way to route the wire out of the solar panel’s enclosure.

http://www.cleanmpg.com/photos/data/522/HCH2SP_OpeningPanel.JPG
Remove the plastic caps and then the screws fastening the back side of the panel

http://www.cleanmpg.com/photos/data/522/HCH2SP_DivertingWirePort.JPG
Determine the best location for the new hole where the wire will exit through

http://www.cleanmpg.com/photos/data/500/HCH2SP_CuttingSolarPanelWire.JPG

http://www.cleanmpg.com/photos/data/522/HCH2SP_CuttingSolarPanelWire.JPG http://www.cleanmpg.com/photos/data/522/HCH2SP_SolarPanelWireRouting.JPG
Thread the wire through the new hole after using some hot glue inside the panel

In this particular situation I simply made a small hole on the enclosure and passed the wire through it. You’ll also notice that I’ve cut the wire leaving only 2 feet worth. I’ve also chosen to discard the connectors included with the panel since I prefer to use my own for the reasons that will become evident at a later point in this article.

With the new hole made on the back of the unit and the wire re-routed and passing through it, the protrusion is no longer there (just a tiny imperceptible hole remains). At this point I can choose to plug it with bit of black silicone putty if I am focused on this minor detail. After this step is complete we will secure the wiring inside the solar panel with some hot glue and then screw the unit back on to its original state.

http://www.cleanmpg.com/photos/data/522/HCH2SP_LeftOverHole1.JPG
The left over hole can be covered with tape or black silicone putty

The next step will involve setting the anchor points for the solar panel. As many of you will notice we’re using a combination of adhesive foam and Velcro. While we could use the four stainless steel screws and have the unit securely fastened to the rear dash, I dislike the idea of making so many holes on the dash and also not being able to remove at will (cleaning or other reasons). So, my experience has shown that the method I illustrate here suits me just fine, it is quiet, reasonably solid and easy to live with.

To begin, I cut a couple of small strips of adhesive foam (roughly 2 to 2.5 inches long). This foam is pretty wide (roughly 1 inch wide) and it provides plenty of support to the panel.

http://www.cleanmpg.com/photos/data/522/HCH2SP_FoamAndVelcro.JPG
The closed cell foam tape and the industrial Velcro used to secure the solar panel

http://www.cleanmpg.com/photos/data/522/HCH2SP_FoamAndVelcroPads.JPG
TOP: loop velcro , MIDDLE: hook velcro, BOTTOM: Foam pads

This foam can be found at home depot in the weather proofing section and its adhesive properties seem to be good enough to withstand the coldest days (-45F) and also the hottest (110F) without coming loose. Although not absolutely necessary, you may also sand the foam pad on the outboard edge to make it easier for the solar panel to land on it as flatly as possible.

I also cut three strips of industrial Velcro. This Velcro can also be found at Home depot or other hardware stores and does a pretty good job of securing and silencing the setup.

http://www.cleanmpg.com/photos/data/522/HCH2SP_SolarPanelReadyToDeploy.JPG
Foam and Velcro pads ready to be placed on the rear dash

Two of the smaller strips (hook side) were "glued" against the foam pads while the larger segment will hold the panel at the lower end. You may choose to use a different number or length of Velcro strips but I have found these to offer the securing effectiveness it needs without being a pain to pry the panel off at a later time. The remaining strips (loop side) that match the 3 (Hooks) segments will be glued against the back side of the solar panel as shown below.

http://www.cleanmpg.com/photos/data/522/HCH2SP_VelcroLoopPad.JPG
Solar panel with the loop side Velcro pads on

To make sure that the Velcro and the adhesive foam adhere properly, I simply wet a couple of cotton swabs with some alcohol or vehicle wax remover and wiped the surface of the dash trim where the Velcro and foam will attach. Doing this will ensure that any oils, dust or surface treatments (like Armorall) don’t get in the way of a solid adhesion. :)

Once the foam pads and Velcro are attached, we can then feed the wire from the solar panel downwards through the small hole we made earlier from the trunk. Doing so may require getting a stiffer wire (fish tape) trough the orifice first just to make sure the conductor arrives on the other side without too much fuss. Once the wire is on the other side we simply “press” the solar panel onto its final support points and just let it be for a good day or so. You may choose to place a small book on top of the panel to make sure some pressure is applied while the adhesive does its job. Prying it off too soon may reduce the effectiveness of the adhesives... so we should be careful in positioning the Velcro and the pads as you should only give yourself one chance to get this right.

http://www.cleanmpg.com/photos/data/500/HCH2SP_SolarPanelMountedInsideView.JPG
http://www.cleanmpg.com/photos/data/522/HCH2SP_DolarPanelMountedInsideView.JPG
What the mounted panel looks like from the inside of the vehicle

Anyway, at this stage we’re ready to start working on the wiring. The first thing we’ll need is to make sure that this installation is protected by an inline fuse. You’ll also need to do some crimping because quite frankly we want the install to be easily disconnected should Honda ever raise it as a troubleshooting issue.

http://www.cleanmpg.com/photos/data/522/HCH2SP_Connectors.JPG
A good collection of male/female connectors and your average crimper

http://www.cleanmpg.com/photos/data/522/HCH2SP_OtherTools.JPG


The other tools...

There are many different types of inline fuse assemblies and I don’t really have a preference for any in particular. As long as they are effective and easy to work with then I am pretty much OK with them. These fuse kits can be found in most auto parts stores (NAPA and Auto-zone) or the automotive departments of larger retail stores (Walmart, Sears).

For protection I would suggest using any fuse rated for 500mA or higher, but no higher than 5A. In this install I chose to use a 3A fuse as it is very common and easy to find replacements for.

http://www.cleanmpg.com/photos/data/522/HCH2SP_MiniInlineFuseOEM.JPG
The original retail inline mini fuse kit with a bullet type connector. Fuse is absent.

http://www.cleanmpg.com/photos/data/522/HCH2SP_MiniInlineFuseModified.JPG
The inline mini fuse kit altered to fit a different "flat" type connector. Fuse is mounted.

http://www.cleanmpg.com/forums/../photos/data/500/HCH2SP_InlineFuses.JPG
... and an alternate inline fuse kit configuration

Running the wire(s)

We only really need to run one wire all the way from the trunk to the fuse panel underneath the driver’s side dash. The wire that we are talking about will carry the positive (+17v) voltage from the panel and will be connecting to the inline fuse which in turn will connect to an available fuse socket on the fuse panel (the actual connection to the fuse panel will be done later). This wire can be easily routed through the trunk into the passenger cabin from behind the seat on the driver’s side) and underneath the side trim. If done patiently and properly it should not only remain easily concealed but also very safe. The alternative to this is to remove the plastic trim and secure the wire against the vehicle’s metal structure. It is up to you.

TIP: Use some heat shrink tubing or wire loom while running the wires through any the vehicle's pre-drilled holes.

http://www.cleanmpg.com/photos/data/522/HCH2SP_TrunkPreWiring.JPG
Examine the path for your wiring before laying it out

http://www.cleanmpg.com/photos/data/522/HCH2SP_TrunkWiring.JPG
Running the wires and crimping the connectors inside the trunk


http://www.cleanmpg.com/photos/data/522/HCH2SP_TrunkWiring2.JPG

Lastly we can connect the remaining wire (ground) to a suitable ground point on the vehicle. In the trunk you’ll find a few grounding points around the tail light areas (under the trunk lining) and you’ll also find several on the IPU chassis. I often chose to establish the ground connection on the IPU chassis which can be easily accessed by pushing the seat cushion just a little. If this approach is still awkward for you, then you may choose to remove the seat back entirely or adopt another ground point in the trunk area. However, first we should prepare our ground end connector:

http://www.cleanmpg.com/photos/data/522/HCH2SP_GroundPointConnector.JPG
Using the panel's remaining ground wire or another equally suitable wire we attach a proper connecting end to it

An example of a possible ground point connection in the vehicle's trunk area is provided below. Usually these ground points are found close to the tail lights underneath the trunk vertical lining.
http://www.cleanmpg.com/photos/data/522/HCH2SP_GroundPointLocation.JPG
Connecting the newly crimped U connector to the ground point.

Once all the wiring is in place we should use a voltmeter to see if the +17 volt wire arriving from the panel provides the expected voltage readout (it kind helps to be outdoors for this to work :) ).

http://www.cleanmpg.com/photos/data/522/HCH2SP_FusePanelBefore.JPG
There are several empty fuse locations where to plug the solar panel we chose socket 6

If we read 17 Volts on the red wire, then we simply plug the (red) wire onto an available fuse kit connector (as shown in the following picture). If you can not read 17 volts, then make sure all the connections are properly secured before attempting to connect.

http://www.cleanmpg.com/photos/data/522/HCH2SP_FusePanelConnect.JPG
Plug the solar panel into the fuse kit only after testing for a 17Volt reading.

Optional improvements

You may choose to also install a small LCD current meter to measure the amount of current your panel is providing to your 12V system. This will help you assess how effective the panel is and whether it is working for you at all.

http://www.cleanmpg.com/photos/data/522/HCH2SP_LCDAmpMeter.JPG
(Actual "installed" images will be provided soon)

Conclusion

From a rather personal perspective this solar panel is an absolute necessity because my car has several “always on” systems, two of these (Alarm and surveillance, along with the Electronic rust protection) consume too much for the little OEM 12V battery to take. A panel like this will not only help supplement those losses but will also ensure that even in the coldest of days your 12V battery will remain healthy.

Of course, this mod also helps the fuel economy aspect since less IMA charge is diverted to keep the 12V subsystem topped off and that means I don't have to work as hard to manage my SoC. ;)

If you have any questions or feedback regarding this modification please submit them on this thread.

Cheers;

MSantos

Manuel,

Before I saw your post on installing a solar panel, I had this idea for my 2001 Prius (which I bought today): Installing a small solar panel that would charge a small supplemental battery (like the 12 volt / 7 amp hour lead acid portable power system battery (that I just bought for another purpose). This battery would be used to run a block heater which would come on when the car was first turned on (or, better yet, when the remote was used to unlock the doors to sped up the process.) Excess power from the solar panel could, perhaps, be used to charge the existing 12 volt battery.

I don't know nothin' 'bout no electricicals, so what do you think? Any merit to this idea?

Thanks. Your newbie friend,
Gary

Thanks for a detailed write up.
I'm sure others will have more feedback.
I look forward to seeing more.

...This battery would be used to run a block heater which would come on when the car was first turned on (or, better yet, when the remote was used to unlock the doors to sped up the process.) Excess power from the solar panel could, perhaps, be used to charge the existing 12 volt battery.


Hi Gary;

The idea has a lot of merit and has already been discussed a few times here at CleanMPG.

In order to achieve something like that, your solar power generation would have to be massive and in addition to that, you would need a good array of SLA batteries simply because a standard block heater eats roughly 400 watts and you cannot really afford to completely deplete your batteries - otherwise their life is very short. To add insult to injury, the engine block takes a good couple of hours to warm up effectively. I believe you can see our problem as it clearly starts getting very impractical: Massive solar panel(s), beefy battery bank, power control circuitry, etc....

With that said, the biggest culprit or impediment is energy storage efficiency and the implicit conversion losses. The less conversions there are the more efficient the solar recovery system is; and despite the current state of technology and progress, I am afraid we're not there yet. :(

Cheers;

MSantos

Great writeup and find on the panel, Manuel!

I finally managed to find the panel pictured in the installation. I did some testing on its output and found that connecting the panel to my car's electrical system brings the panel's voltage down to about 12.6 volts. On an overcast day, the panel put out about 30mA, which increased to 90mA on a sunny day. The panel angle affects the output more than I thought it would. Laying it horizontally reduced current flow to about 70mA on the same sunny day. Best results for me were with the panel at a ~40 degree angle from horizontal. My windows also really kill the output. Simply putting the panel on my car's roof at the same angle increased the current from 90mA to 140mA. I don't have any significant tint on my windows, but the glass may be designed to absorb some solar energy.

I will have to create some sort of device to keep my panel up at an angle for optimal output. I'd also like to capture the energy that is being lost through my windows, but I don't know if that is possible.

Glad you managed to find one as they kind of cleared out in a big hurry. ;)

I certainly agree with you that the windows account for a measurable loss in the panel's output as I see that as well. However, there may be other attributes of an install that can have a small bearing too. Here are some observations I also made in my case:
- The panel's output is significantly lower if the panel is installed on the front dash as opposed to the read dash. Why? Here are some of the possible reasons:

In my case, the rear glass has a lower tint gradient
Depending on the sun's angle, the glass refraction factor is less aggressive so the light travels "more" perpendicularly through the glass (in my case).
The rear dash is in a bright color and with the reflective index of the rear window that helps bounce some light back down into the panel. The front dash is very dark in color and that helps kill the output by a tiny bit. This effect appears more noticeable in a cloudy day.A sun-tracker module? I suppose making one from an assortment of RC or toy components could be effective. The way I see it , the tiny challenge is when powering the semi-smart tracker circuit (even if built entirely on CMOS tech) as it begins to eat into the battery in a not so bright day especially since the panel is not assured of the clear view of the sun like a normal fixed application would. :o

Making a manually operated one would be very cool indeed. ;)

Capturing energy lost through the windows? That is a great idea.
On an almost related note, my dream is to one day find a practical solar voltaic/LCD film that can be applied under the windows (glass embedded is even better) to capture the light while the car is parked and also provide an adjustable tint factor when driving it. :)

Cheers;

MSantos

I wish I had thought about this when I had my 06 Civic EX. Its battery and charging system was junk. It had no headroom at all. They cut it so close I put it in the poor engineering category.

Im sorry to hear the HCH-II suffers from the same issue. :(

Any updates on this mod?

FYI, I decided to try something similar in my Nissan Altima Hybrid. No FE info yet, but I posted some pics over here (http://www.cleanmpg.com/forums/showthread.php?p=164353#post164353).

Eph

would this benefit a non-hybrid car in terms of FE?

It can't hurt, Tofuman. I use mine mainly to keep my battery up during the dead of winter. Sometimes my car won't move for 2-3 weeks, and I noticed the battery felt kind of "flat" for that first start after sitting that long, especially if it was during one of our -20F cold snaps.

I was cleaning out my car today and noticed that the wire had broken right where it meets that springy part on the side of the panel. My panel was mounted in the back of my car on a shelf that tilted up with the hatch when it was opened. Maybe that repetitive movement was too much for that joint to handle? I'm not sure how to fix it yet, but will investigate soon.

I velcroed one to my dash a few weeks ago, it gets plugged into the cigarette lighter and it produces enough power during the day to fully charge the battery after an insane amount of night time driving 5X a week and also will power my radio, which used to never play when the ignition switch was off and the power switch to the radio was on. Also during the day when I FAS I don't lose any radio time when I turn the ignition back on at a green intersection. That's way cool.

The first day I got up and went towards my car I thought my neighbors were listening to NPR. :) They weren't. I now power off my radio when I come home at night so it doesn't play in the carport while I sleep during the day from the solar panel. Mine is a 1.5watt output amorphous solar panel from www.harborfreight.com regularly $15.99, on sale occasionally for $12.99 - Dale

This just seems cool. Thanks for the info.

Is this the one you purchased from Harbor Freight?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768

Is 1.5 Watts a lot? (Electricity is a mystery to me.) How long would you guess to recharge a battery with that panel?

... Is 1.5 Watts a lot? (Electricity is a mystery to me.) How long would you guess to recharge a battery with that panel?

Speaking not as a car hound, but as an electrical engineer with a hobby-size solar panel on my house roof for the past 15 years:

Is 1.5 Watts a lot? No, it is tiny.

How long will it take to recharge a battery with this? It will never recharge. Even under ideal conditions -- mounted outside the car (no glass in the way), no clouds, no shading -- it would need an automatic sun tracker pointing it directly at the sun all day, just to collect enough energy to make up for the self discharge of the battery.

If you had it at the South Pole during summer, with 24-hour sunlight and an automatic sun tracker, it might charge the battery in a few weeks, depending on the battery size. And not counting the power to operate the tracking motor.

I velcroed one to my dash a few weeks ago, it gets plugged into the cigarette lighter and it produces enough power during the day to fully charge the battery after an insane amount of night time driving 5X a week and also will power my radio, which used to never play when the ignition switch was off and the power switch to the radio was on. Also during the day when I FAS I don't lose any radio time when I turn the ignition back on at a green intersection. That's way cool. ...

From your description, I must seriously question whether it is charging the battery at all.

Is your cigarette lighter turned off when the ignition is off? If so, plugging a solar charger into the lighter cannot charge the battery while you are away.

The fact that the radio will not normally play with the ignition off, but will play with the solar charger plugger in, very strongly hints that this is the case.

Would a larger, 5 watt solar cell such as this be too much of a good thing?

http://www.costco.com/Browse/Product.aspx?Prodid=11313627&search=solar&Mo=21&cm_re=1_en-_-Top_Left_Nav-_-Top_search&lang=en-US&Nr=P_CatalogName:BC&Sp=S&N=5000043&whse=BC&Dx=mode+matchallpartial&Ntk=Text_Search&Dr=P_CatalogName:BC&Ne=4000000&D=solar&Ntt=solar&No=6&Ntx=mode+matchallpartial&Nty=1&topnav=&s=1

Just thinking about doing this DIY this summer.

Mike

Hi Mike;

For the HCH-II a 5 Watt solar panel is not too much.

In fact, I've added yet another 2.4 W solar panel to my daily commuter precisely because I had to revise my original requirements. Going much above 5 Watts would likely call for a charge controller.

Cheers;

Manuel

This is looking like a much needed mod for the HCHII. The windows are tinted in the wifes car. Would I need to go for a bit larger panel to make up for the tint?

Hi Jeff;

Its funny you mention that. I now have a total of 5+ Watts of solar generation available which is not only more than enough to keep my 12V demands in check, but also to provide a tiny bit of surplus power.

After seeing the 2010 Prius with a solar roof powering the cars ventilation system, I revisited the idea and I am thinking of powering a small DC fan with roughly 160-180mA @ ~12V on tap.

Is this what you were thinking of doing as well, or just keeping the 12V topped off?


Anyway, just to stimulate additional thinking among the community I'll introduce the following:
http://www.sphere.bc.ca/test/fans/fans10/mechatronics-e1225l12b-fan.jpg http://www.sphere.bc.ca/test/fans/fans10/mechatronics-e1225l12b.jpg

There are many areas where a fan like this be placed. My preference is to install it in the trunk area between the lining and the outer body shell and then drive a duct all the way to the rear dash. Open a neat hole in the rear dash right around the IPU vent and cover the hole with a nice grille. Then, make sure we have a temp activated switch that will kick the fan ON and also place a blocking diode to make sure the power comes from the solar panel and not the 12V battery.

By my rough estimations this fan (55CFM rating, 1800RPM, 5-blade design, 32dBa, low noise) can move a bit of stale and hot air out of the car when under the scorching sun. More would be better, but in my books this is definitely better than the alternative.


Cheers;

MSantos

Hi Jeff;

Its funny you mention that. I now have a total of 5+ Watts of solar generation available which is not only more than enough to keep my 12V demands in check, but also to provide a tiny bit of surplus power.

After seeing the 2010 Prius with a solar roof powering the cars ventilation system, I revisited the idea and I am thinking of powering a small DC fan with roughly 160-180mA @ ~12V on tap.

Is this what you were thinking of doing as well, or just keeping the 12V topped off?

Cheers;

MSantos

One step at a time. :) My main concern is how much the tint would hurt the panel's ability to keep the 12v topped off?

I'm sure folks here will get PIII's with the panel option. I'm also sure the ins. for such a config'ed car would be higher seeing the hail we get here.

Jeff, I would suspect it would cut its effectiveness significantly. Let me illustrate:
The OEM glass tint is enough to "eat" 30-40 mA out of a 2.4W panel (120mA) and depending on angle of the solar panel vs the window glass and the light source (sun) the loss may be even higher. :(

Obviously, tinting the rear window would not be a priority for me with a rear mounted solar panel in the wings. The front mounted SRS also make it less safe to mount the panels on the front dash. We could go with flexible or film-based panels but their power yields seem a bit low for my liking.

Hi Jeff;

Its funny you mention that. I now have a total of 5+ Watts of solar generation available which is not only more than enough to keep my 12V demands in check, but also to provide a tiny bit of surplus power.

After seeing the 2010 Prius with a solar roof powering the cars ventilation system, I revisited the idea and I am thinking of powering a small DC fan with roughly 160-180mA @ ~12V on tap.

Is this what you were thinking of doing as well, or just keeping the 12V topped off?


Anyway, just to stimulate additional thinking among the community I'll introduce the following:
http://www.sphere.bc.ca/test/fans/fans10/mechatronics-e1225l12b-fan.jpg http://www.sphere.bc.ca/test/fans/fans10/mechatronics-e1225l12b.jpg

There are many areas where a fan like this be placed. My preference is to install it in the trunk area between the lining and the outer body shell and then drive a duct all the way to the rear dash. Open a neat hole in the rear dash right around the IPU vent and cover the hole with a nice grille. Then, make sure we have a temp activated switch that will kick the fan ON and also place a blocking diode to make sure the power comes from the solar panel and not the 12V battery.

By my rough estimations this fan (55CFM rating, 1800RPM, 5-blade design, 32dBa, low noise) can move a bit of stale and hot air out of the car when under the scorching sun. More would be better, but in my books this is definitely better than the alternative.


Cheers;

MSantos

That looks like a 120mm fan. Some fans you can wire up to run at 5 to 7v. A lot of 120's respond well to this and move a lot of air. Computer mod folks have been doing it for years. I do it with a reobus on my four 120mm fans for my radiator on my main water cooled rig.

I would think it would be best to use such a fan in the IPU fan duct. I have not seen the duct yet. so maybe a 80mm fan would work.

...
I would think it would be best to use such a fan in the IPU fan duct. I have not seen the duct yet. so maybe a 80mm fan would work.

I thought about that but I decided against it because:

It would be right there in the IPU air stream as a potential air-flow obstacle.
I don't want warm cabin air to circulate over the critical IPU modules while the car is baking under the sun.
The volume of air I can move is limited by the solar power I can produce and I prefer (for now) a larger diameter, quieter, lower RPM fan to do the job. The IPU duct cross section is too small for me and I would have to increase the air speeds to move a measurable amount of air. 55CFM max that this 120mm fan can provide may just do the trick for me.
I don't want to interfere with or modify any the OEM hybrid systems. I did that in 2006 and as a result I had to replace over 50% of the IPU subsystems in order to regain my warranty. :(What do you think?

Maybe the cabin ducting system then?

If you pull out the rear passenger side trunk liner, there's a round opening with attachment holes around it between the duct work from the IMA batteyr and the fender. It is a perfect place to mount a fan like. I'm optimistic that it would help to keep the IMA battery cool and prevent recals but would it help in cooling the cabin any?

Hi Jeff and Mike;

Toyota did integrate the solar powered blower right into the HVAC system on their 2010 Prius but I fear it would a bit of a challenge to do it on the HCH-II with the types of low power fans I was considering::

There's almost not space that I can see where we may insert a fan, no matter how small, inline with the HVAC ducting.
If we did, then the fan would be bombarded by very hot air in the winter. DC fans have internal circuitry and don't like a lot of heat.
It would probably interfere (resistive) with the HVAC air stream when the solar powered fan it is not working.Now, I've been thinking about this and so far the easiest approach I see, is to place a 120mm round hole in the rear dash tray and mount the DC solar powered fan there. What this would do is draw the stale and hot air from the cabin into the trunk while the car is parked under the sun.

Of course, the fan would be mounted under the tray (lots of room there) and we would need to put a nice grill to cover it, and that could work very well. In my case, I would not need to cover it because the solar panel would be right there, 1" right above it. This mod wold eat no trunk space at all.

As you know, the trunk has two vent vanes on each rear corner of the vehicle so the hot air in the trunk would be forced to exit through there. At a max of 55CFM and leaving the front dash vents on open, we could see better cabin temps when arriving to a locked car in a warmer summer day.

Hummm... maybe we could even shut off the climate control altogether when driving in a sunny day... ;)

Now, I just put together a simple schematic for a small thermally controlled circuit to drive a 120mm DC fan and what this would do is throttle the fan according to the temperature since we don't want the darn fan to go ON during a colder winter day. In total, the little circuit will cost $2-$5 worth of components and should still allow some solar power to still make it to the battery.

In have a feeling this mod is about to take form one of these weekends. ;)

Cheers;

Manuel

I have fans.... Need a panel. :)

I'll buy a Santos HVAC, Battery topping kit.

Here is some testing that has been done with fans used a lot when water cooling computers. The is a lot of valuable data in these links.

http://www.xtremesystems.org/forums/showthread.php?t=221899
http://www.xtremesystems.org/forums/showthread.php?t=223391
http://www.xtremesystems.org/forums/showthread.php?t=171661
http://www.xtremesystems.org/forums/showthread.php?t=193126

Fan Grill and Filter
http://www.xtremesystems.org/forums/showthread.php?t=209801

Hope this helps.

I just picked up 2 solar panels on sale at Costco today. They have an auxiliary outlet plug and 2 clamps for battery terminals. Here is my question, can I simply bypass the relay that shuts off the 12v aux power so that it is constantly hot and connect the solar panel via the aux outlet to charge the 12V battery or must I run wires as in the DIY?

I intend to tint the side and rear windows this summer and will attach the solar panel with the included suction cups to the base of the windshield, removing it when driving. The car sits out mostly now since my wife keeps the Insight in the garage and there will be ample opportunity for solar charging.

Hi Mike;

The bypass of the relays has been performed in the past so I am pretty sure it could work for you as well.

However, I would still suggest you run the wiring straight to a live connection on the fuse panel since that also gives you an opportunity to fuse the panel with a lower fuse value. This approach will look cleaner and compliant just in case a Honda technician ever raises the issue for whatever reason. Unfairly or not, the inferred warranty consequences can be quite severe.


Cheers;

MSantos

Good point. Since I already have the fog lights in the #6 slot, I assume any slot will work?

Use a volt meter on the remaining empty ones to confirm but you should be OK with an alternate socket.

Hi Manuel,

My only add-on accessory on my HCHII is an electronic anti-rust system installed by Honda when I bought the car. Since my car is usely sitting in my drive way (I don't commute anymore, being retired) I was tinking of using a small battery charger installed under the hood that I could connect from time to time to charge the 12 volt battery. This way I could charge it to its maximum every time if I can. What do you think?

Cheers,

Jean Binette, Dunham, Québec

Hi Jean;

Those electronic anti-rust systems can be real power hogs on the poor 12V battery... I should know since depending on the weather conditions, mine actually consumes varying amounts of power.

So yes, that is a great idea. I wholeheartedly agree on getting a battery tender or some other SLA generic charger plugged onto it. ;)


BTW: Welcome to CleanMPG !!!! :D


Cheers;

Hi Manuel,
I'm looking around the web for a solar panel for my car, and there are a lot of different options and terms out there (eg, amorphous, mono/polychrystallline, overcharge/discharge protection). What features and electrical parameters should I be looking for in a solar battery maintainer for my car? Anything I should avoid?
Thanks.

...
I'm looking around the web for a solar panel for my car, and there are a lot of different options and terms out there (eg, amorphous, mono/polychrystallline, overcharge/discharge protection). ...

Hi Matt;

Amorphous panels are the most affordable and still quite effective for low power operations. The ones that I have used have served me very well and I got lots to show for it. Not only the 12V battery on my 2006 HCH is as good as new after 3+ years (NO JOKE) but the same can be said of other cars that had the same retrofit shortly after (HCH-II's and Prius-IIs).

And we all know what happens when the 12V charge is less than optimal? Yes, shorter lived battery and less than optimal FE for the time it lasts - and that is the truth.

However, the thing to watch for when using a solar panel, is overcharging the 12V battery. Even though a small 2-5 Watt panel may not seem like much, the darn things will work very well when left in the sun for extended periods of time. Any power above 5W will probably require a charge controller to avoid overcharging the 12v battery. Fortunately, these charge controllers are not very expensive ($20-$30) and work very well.

Discharge protection refers to the presence of a (2 cent) diode that prevents the current from flowing in the reverse direction... which at night would drain power from the battery. Almost all consumer ready small panels have this built-in.

With all this said, I have upgraded my solar arrangement yet again. This time to mono-crystalline VERY lightweight panels producing 10-50 watts. This is because my demands have also gone up substantially and I am also eying even more benefits.

I'll post some pictures soon. ;)

Cheers;


MSantos

I ended up pulling my solar panel out of my Altima Hybrid, as I could not measure any FE benefit to it in my car.

Thanks, Manuel. Can't wait to see your latest upgrade.

Turns out you got an outstanding deal with the 2.4 watters for $10. After an exhaustive web search, unable to find a deal anywhere near as good as yours, I decided to go with a couple of the 1.5 watt Coleman units offered by Costco. Do you see any problems attaching the positive wire directly to the fuse box with a fuse like you did with the tpms unit?

OK, here we go again. This time my solar power generation was bumped up to 15 watts of ultralight, mono-crystalline goodness.

I had bought quite a bit more power and at first I intended to fit it all in (up to 30Watts) but I decided against it since it would be a bit of a waste - at least for the time being. I realized that 15 watts is now more than sufficient for the power demands I have in the HCH-II.

One good outcome of this upgrade is that the solar assembly I got now is ~4 times lighter than the previous one. The new panels are just a few milimeters thick and with an aluminum backing now they are not only light but also very flexible.

So let's see, I went up tripled the generated power and I cut the weight to just one quarter of the former setup. I am happy.

Did I get a charge controller installed? Nope. Not yet, and like I said previously I have no need for one since the 12V battery will take all it without overcharging. Since these are the raw panels, I still had to retrofit the panel with a diode just to prevent the battery current from flowing in the opposite direction at night. No problem though since diodes are some of the most common items on my bench.

So here are the pics of the new panel setup.

http://www.cleanmpg.com/photos/data/500/SolarPanel_15Watts_HCH2.jpg
Like the previous setup, the new panel is attached to the rear deck platform with industrial velcro. Noiseless, secure under all weather conditions and leaves no traces if ever removed.


And now a special treat for the other new hybrid in my fleet:
http://www.cleanmpg.com/photos/data/500/SolarPanel_5Watts_3GPrius_j.jpg
A nice 5 watt solar panel velcroed in on the front dash of the 2010 Prius...

... with yet another 15W unit attached to the rear cargo cover at the rear of the vehicle.
http://www.cleanmpg.com/photos/data/500/SolarPanel_15Watts_3GPrius2.jpg

OK, I know what some of you are thinking: That's such an odd place to place a solar panel. What if you need to carry something large and the cover has to come off?

Well, that's pretty easy actually. The solar panel has a connector that unplugs from a concealed wire that climbs up the middle of the rear seat... and it too is attached with industrial velcro to the aluminum cover cartridge. In other words, easy to remove and easy to re-install.

In reality though, I rarely use the Prius to carry anything I cannot carry in the HCH-II. I know this does not help capitalize on the Prius' much touted advantage over a car that cannot even fold its seats, but in my case it is the absolute truth. For folks like myself the cargo versatility of the Prius is seriously overrated and not worth making a car choice on this attribute alone. Sorry. :rolleyes:

Anyway, why did I install two panels on the Prius totaling 20 watts?

Because the 2010 Prius will take it all and much more. In fact, I have a 30 Watt flexible panel that will be installed over the rear cover and it will not only help power the solar cooling setup on the Prius (similar to what I did on the HCH-II) but it will also help supplement the 12V battery charge as well.
In this setup I will use a charge controller however.

The "how to..." for the Prius will arrive sometime in the future.


Cheers;

MSantos

This is exciting, Manuel! I eagerly await your how to for the Prius. :D

Can you provide a link to purchase the raw panels?

Also, why do you feel that the controller is not needed?
I had one in my setup, but always wondered whether that was limiting the benefits, as it seemed to stop charging too early....

Hi MSantos,

How has the fan set up been working out for you? Do you still feel it was worth the install? I've been considering it, but keep putting off. My windows are tinted 35%, so is there a particular type of panel you recommend when using w/ tint?
I would like to keep it to 1 panel, if I can. Is it worth it to have 4 fans to one panel or is 2 truly better in a 4 fan set up?
Are you still happy w/ the type of fans you're using or have you found anything better since?

Sorry for all the questions, too.

Jess

Do you have any pics of the fan set up?
You ever try anything for the winter in terms of heating?

Hi cephraim;

Most vehicles do not drain much more than 50mA from the 12V battery while powered off. For that reason you have to be sure that you do not overcharge the 12V battery whenever your generated power goes above 5 watts. That is why we always recommend a charge controller just to saty on the safe side. Now, depending on the charge controller you may or may not have additional losses that nullify the value of the panel's contribution.
For instance, if the charge controller consumes let's say, 30mA... then that is 30 mA of current that will not make it into the battery. The more it consumes the less effective the solar panel setup is. Try measuring the power demands of the car and that of the charge controller, then decide if you are better off without a charge controller at all. Also keep an eye on the 12V battery to make sure it does not overcharge.

In my case, my car is consuming much more tham 100mA at all times. This is because I've added a host of additional systems that are ON all the time. The most recent and also the most power hungry is a 2 camera video surveillance system. Given the significant power drains I am going to forgo a charge controller altogether on my HCH-II.


Jess:

The Solar powered cooling mod (cephraim, pics are provided here too) (http://www.cleanmpg.com/forums/showthread.php?t=22764&page=2) worked so well that I am definitely going to put in on my 2010 Prius as well. In fact, I even ignored the Prius OEM solar solution not because the hardware is not good (it is in fact excellet with 60Watts of generated power), but because the implementation and usability is so limited darn limited.


No, I did not contemplate the "heating" part. Quite frankly, I am not too sure how to go about doing it with the current state of technology.

The vendor I obtained my solar panels from also has an eBay outlet. You can find it here. (http://shop.ebay.ca/g-man2222205/m.html?_nkw=&_armrs=1&_from=&_ipg=)

Cheers;

MSantos

Is the trunk light circuit always on ( before the trunk light switch )?

If so... Why bother running a wire all the way to the front of the vehicle?

The wire bringing 12v to the trunk light switch can be back feed with the solar power!!