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Thread: Cheep VW Solar Panels and DIY LED home lighting.

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    Flashaholic Brlux's Avatar
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    Default Cheep VW Solar Panels and DIY LED home lighting.

    Since several people have voiced interest in setting up there own Solar Powered Led home lighting in my 2 Solar Powered LED home Lighting threads Part1 and Part2, I thought I would wright up a little bit of information on the VW Solar panels. If someone wants to purchase some real Solar panels, a charge controller, and some deep cycle batteries then by all means go for it I don't think you will regret such a decision. Just be prepared to spend several hundred dollars. If someone is just a bit curious about the idea and wants something to play and experiment with and doesn't want to make that kind of financial commitment then this thread is for you. I will be discussing the VW Solar panels which can bu used to build a small PV system which is well suited for running a few home lighting LED's and should have a complete build cost of well below $100.




    Volkswagen started suction cup mounting small PV (Photo voltaic) panels inside the windshield of there cars so that the batteries would not go dead while being shipped to the dealer. There now seems to be no shortage of these panels on Ebay try searching for VW Solar.







    There are 2 different types of VW panels the older ones were made of Polly Crystalin PV cells (Blue cells) and are rated at 3.2 Watts. In direct sunlight they are specked to charge a 12V battery with about 170mA though of 4 I have played with all have slightly surpassed this speck with the best one put out up to 230mA in the Arizona sun.




    A charge controller is an important part of a PV system and for some reason people sometimes think they can do without one. I used to think this as well when I first started playing with PV panels a few years ago. I had a nice sized 75 amp hour deep cycle battery and thought that one panel would not damage by battery especially if I was continually using power out of it on a daily basis. Well I destroyed my battery within a few months and bought a new battery and charge controller shortly ther after. Maybe Volkswagen learned the same lesson because the first Polly Crystalin panels plugged into the cigarette lighter with no charge controller. They lated added a small charge controller circuit inside the cigarette lighter plug. Of the 4 panels I have played with 2 had charge controllers and 2 didn't. All 4 panels were identical on the exterior with no visible way to tell which had a charge controller and which didn't.




    The only possible way to tell without taking the plug apart is perhaps by the manufacturing date stamped on the back. The oldest one that did have a controller was stamped Dec 30th 2004 So I am going to predict that if you get one with manufactured in 2005 or later it should have a charge controller in the cigarette lighter plug. There also appears to be a version of this panel that plugs into the cars OBD2 diagnostic port and it came out sometime in 2006. I have never played with this particular panel so I can't say if it has a controller or not but I would hope so.




    The newer panels are produced by ICP solar and are made of a thin film on glass (Amorphous) panel. They appear brown/burgundy in color and are rated at 4 watts. I just acquired one of these newer panels a few hours ago and although I have not experience with them long term as I have the older models I think I can still give some insight on them. You can probably expect them to charge a battery at 275ma in peek sunlight. They have a small box in like with the cord which is the charge controller and they plug into to OBD2 diagnostic port.




    The real advantage that the VW panels have over your average solar battery maintainer that you would find in a automotive or department store is the included charge controller circuit and they have higher power output than most other battery maintainers I have seen in the store.







    Now to talk about how to improve the charge controllers. I like it when things give me feedback and let me know what they are doing. Most charge controllers tell you when the battery is fully charged or how close it is to being charged. The older panels controllers had a place on the PCB for an LED which was not installed but can be easily added. You can see the white wires I added which go to a remote LED you will also need to add a resistor to the spot on the PCB marked R10. I used a 4.7K ohm but you can probably use anything between 1K to 7K ohms, just remember you want to be able to see the LED but dot have it suck up much of your valuable power. I added extra wire to the input and output of the controller and screwed the cigarette lighter case back together and allowed it to still act as a housing. One added feature of this board is that it used a .5A PTC resettable fuse for protection. If it ever gets tripped just remove power for a few seconds and it will reset. I am assuming this means it is good for controlling up to a max of .5A or current. I have ran 2 of the older panels on one charge controller and it all seemed to work fine.




    The newer ICP charge controller is a much simpler design but from my brief testing it seemed to work well. It has a .5A glass fuse for protection which will need to be replaced if something goes wrong. The main power transistor is a large TO220 and appears to be rated for 3 amps but as it is the design does not have the heat sinking which would be necessary for that kind of current. There is also a pass through diode which is likely only rated for 1Amp. So if the diode was improved upon and some heat sinking was added to the transistor this charge controller could likely be used for up to 3 amps. You probably will need to lower the value of R4 to something like 200 ohms for it to work at these currents. I added an indicator led by soldering a resistor (same choice criteria as the other controller) to the ground connection and connecting the other side to the cathode of a LED. The anode (+) of the led is connected to the side of the large 500 ohm resistor (R4) that is loser to the legs of the transistor.




    These indicator LED's will be illuminated when the battery is being charged. When the battery is near full the led will begin to flash, the duty cycle will reflect the state of charge, the longer it is off the more charged the battery will be.




    In the past I did a small experimental system using one of these older panels I used the 12V 7Amp hour SLA battery out of my Thore spot lite. Small 12V lead acid batteries should be easy to come by, just make sure it is a good one and not the fried one out of that old UPS in the scrap pile.




    As far as LED's are concerned you should have a whole pile of candidates waiting to be put to good use with all the Cree (or whatever the LED of the month currently is) upgrades going on. Those old LED's will work great. Just wire 3 in series with an appropriate current limiting resistor. I used a switch box with several different resistor values I could switch in to give me different drive currents. I ran my test setup with these parts for several weeks and it worked great. My charge controller indicator LED was showing my battery was reaching a full charge almost every day. I got ambitious and hoked up my Rayovac battery cooker (charger) to the system and used it to charge a couple NiMH cells. It probably was not a great idea because the battery did not reach a full charge again before I took the system down probably less than a week later. So be realistic and don't expect a 3.2 watt panel to run your computer and refrigerator, well you get the idea. It is a lot of fun trying to be as efficient as possible and seeing how much you can get done with as little resources as possible.
    Last edited by Brlux; 02-20-2007 at 11:27 PM.
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    Flashaholic* Newuser01's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Hello, Brlux.

    Great thread. Lots of info even for newbie like me. I could follow these instructions to the letter and get a mini solar/led setup running without too much trouble.

    I would ask if you could add some pictures and just a bit more info on what kind of led/heat sinks, wiring, and resistors used for "say" 1 battery/charger system would use?

    That would be great.
    I'll look out for one of these to power reading lights for the study desk or even 2 sets of led's for 2 desk. What do you think?

    One last thing would be, of a set of 3 luxes would be enough light to do studying/reading on a desk?

    Regards.
    Last edited by Newuser01; 02-21-2007 at 05:45 PM.
    Noob
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Was the battery damaged because it was overcharged, eventhough you used the battery minimally daily ?

    Or did the battery go bad because of the reverse flow direction to the battery.

    I have one of the original panel and have used it quite alot, though I have not checked the water level lately.

  4. #4

    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    What is the life span of the vw panels. Do they produce less power over time?

  5. #5
    Flashaholic Brlux's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Quote Originally Posted by max52
    What is the life span of the vw panels. Do they produce less power over time?
    All PV panels produce less power over time. Large panels usually have a 20-25 year waranty of no less than 80% drop in rated output. Crystalin panels have been around for a lot longer and the first thin films had widely varing performance over time. But they now seem to be becoming much more reliable product.

    I don't know that there is enough information on these VW panels to say how they will preform over time but based on the fact that they are scaled down versions of the same parts used in large panels I would think they should be OK.

    I have done a bit more real life battery charging with the ICP charge controller and I have a few things to change on my information about it.

    I will see what I can come up with on a tutorial for making the lights.

    I think the battery on the first system died due to over charging. I had a diode to prevent reverse current flow so I know it was not discharging throught the panels at nite. The maximum power point for most panels is around 17V so that means they will keep puting out nearly the same current all the way up to that point. If you have a day or two of not heavaly using your system then the panels can bring your battery up to that votage which will destroy your battery.
    It takes a really inteligent person to know how to spell a word more than one way.

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    Flashaholic Brlux's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    I had been thinking the newer VW panels were a nice improvement but after working with them some more I think I may now prefer the older stile for our application.




    Moisture is the enemy of PV cells and is probably the biggest contributing factor to there degradation. For this reason PV panels laminate the cells inside of a resin encapsulation using a high pressure/temperature press. The older style crystalline VW panels do this the proper way. The newer thin film ones only have a plastic sheet glued to the back and even that is done poorly. The results are Amorphous silicon on the back of the glass exposed to the environment. Even the silicon under the plastic sheet may not be totally protected from the environment due to the lack of lamination. This manufacturing process may have been deemed sufficient for the intended use inside a car where moisture would be less present and because the useful life time of the panel only needed to be a couple of months. But because of this manufacturing deficiency I feel the newer panels are less suited for long term exposure to the outdoor environment. If you choose to use one of these newer panels and you care about the rate at which the panel degrades over the years then steps should probably be taken to seal the panel against moisture. In the previous picture you can also see the electrically conductive epoxy which is used to connect the wires to the back of the panel. You can not solder to Amorphous silicon.




    I have had an older panel on my rack out in the sun for over a year with the only down side being the plastic frame has become brittle.




    I have some modifications for the charge controller as well. It seems as thought the charge controller regulates in a linear manner. The closer the battery gets to float voltage the less current it allows to pass through. This is a different approach from most charge controllers I have had experience with. Most are either on or off and vary that duty cycle as the battery approaches float voltage. My previous LED indicator mod is ineffective for this approach. I moved the LED and resistor across the Emitter and collector of the main power transistor. Now as the transistor begins to limit the current some will flow through our led and illuminate it when the battery is charged. The closer it is to being charged the brighter the led will become. I also added a 3.6 Meg Ohm resistor in parallel with R1 to lower the float voltage. The stock setting provides a 14V float which may have been OK for an automotive application but seemed a bit high for my likes especially for using on a Sealed Lead acid battery. The added resistor lowers the float voltage to about 13.6V.
    It takes a really inteligent person to know how to spell a word more than one way.

  7. #7

    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    This is a very interesting thread. I wonder where could I get these solar panels if I don't own any VW vehicles...

    Thanks.

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    Flashaholic* Newuser01's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    "Brlux" mentioned in another thread that you could contact VW dealers and they will give them away or for very cheap prices.
    But you can also find them on fleabay. Search for "VW solar".

    Regards.
    Noob
    Poor noob who want some lights.

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    Flashaholic Brlux's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Ebay is probably the easiest way to get them, but I have had success walking into a VW dealership. They don't sell the panels but if you ask real nice and can come up with a good reason why they should give you one they may reluctantly let you walk out with one in hand, atleast they did for me. It is abit un comfortable and they will likely try to sell you a new car in the process.
    It takes a really inteligent person to know how to spell a word more than one way.

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    Flashaholic* Newuser01's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Hi! Brlux.
    I saw some Solar-powered lawn path floodlight 4-light set, for about 27 bucks.
    Posted it here: http://www.candlepowerforums.com/vb/...d.php?t=154877

    Wondering if they are any good?

    Regards.
    Noob
    Poor noob who want some lights.

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    Flashaholic* AndyTiedye's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.


  12. #12
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    I've gotten 6x12" panels for $4 apiece at Surplus Shed. I don't know if that's a good price, but they worked well!

  13. #13
    Flashaholic Brlux's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Quote Originally Posted by LEDependent
    I've gotten 6x12" panels for $4 apiece at Surplus Shed. I don't know if that's a good price, but they worked well!
    That looks like a good price to me. I would probably prefer to get the 12"X12" one which is more suited for 12V applications and is $8. I have never had much success soldering to a thin film glass panel and in commercial panels I have seen them use electrically conductive epoxy to attach the leads.
    It takes a really inteligent person to know how to spell a word more than one way.

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    Flashaholic* LEDAdd1ct's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    One of the reasons I love CPF is because with a little searching, you usually
    discover someone else has already asked the exact same question.

    I just picked up a VW solar/trickle charger with the OBD2 connector to keep my battery
    topped off when the car sits for awhile.

    The item I purchased was at a good enough price and with fast enough shipping
    that I gambled, since it was sold "as is, not tested, purchased at an estate sale."

    I don't know much about OBD2 connectors, but I do have a multimeter and a nearby star for
    testing.

    When the panel arrives, which pins should I probe to make sure there is a voltage?

    Thanks, guys!

    EDIT: Oops! Just looked at a picture of one of these, and there are only two pins on it.

    So, no thinking involved as to which pins to test. :-)



    free screenshot

    (sourced from random e-Bay auction)
    Last edited by LEDAdd1ct; 03-15-2014 at 07:18 AM.
    "...and the diode multiplied and grew in brightness. And God saw that it was good."

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    Flashaholic* LEDAdd1ct's Avatar
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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    For the car experts:

    Is the ground and 12 volt wire the same on all OBD2 connectors, or,
    does it vary by car/make/model?

    This unit was designed for a VW; I have a Sable.

    Do all OBD2 connectors share the same ground and 12 volt pins?
    "...and the diode multiplied and grew in brightness. And God saw that it was good."

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    Default Re: Cheep VW Solar Panels and DIY LED home lighting.

    Quote Originally Posted by LEDAdd1ct View Post
    For the car experts:

    Is the ground and 12 volt wire the same on all OBD2 connectors, or,
    does it vary by car/make/model?

    This unit was designed for a VW; I have a Sable.

    Do all OBD2 connectors share the same ground and 12 volt pins?
    It suppose to be a universal standard for all cars using the OBDII. I did a Google search and it shows pin 4 is ground and Pin 16 is Battery Positive but confirm it w/ a volt meter.

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