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Forum Index : Solar : Which solar panels do I need?
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philb Regular Member  Joined: 05/07/2008 Location: United StatesPosts: 96 |
I am looking for solar panels that can be used to power LED's mounted on a vehicle' top carrier. I plan to bolt a ~1m X 1.4m (3' X 4') piece of sturdy sheet of aluminum across the carrier to contain the solar cells and mount the LEDs around the sides to serve as caution/warning lights. The lights could carry as much as 20 amps at 12 volts. (lots of powerful LED's and driver boards!) The driver boards can take as much as 36 VDC, 10 amps each. Dependability and long service life are paramount, that's why I'm using LED's. I know that all solar panels cannot take to bumps and constant movement. Which solar panels would be the best for this application? Any advice? philb |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
What are you creating?? a spaceship. Are you that bad of a driver that you need to warn folks for miles away 
20 amp in leds is huge, and lots more than your headlights use to start with. Its all good and dandy going green with solar panels, but are you really gaining anything or actually loosing. As the panels and rack on the roof will cause wind drag and your fuel eccomony will go down. So i question if you will actually gain as the wind drag is always there where as coming off the alternator the loading is only present when the lights are switched on, hence better eccomony the rest of the time. (no wind drag) The other thing is most lights are used at night and solar dont work very well then. So how will you store the power? Another battery? So adding more weight again to the vehicle...further losses. There is effecient ways to wire leds in to reduce their consumption on power and you might need to research this, as 20 amp is really quite over the top unless you are making a huge TV screen out of RGB leds. Sorry i dont see this as a practical project and far from being energy consious and the use of solar to justifie feeling good about it, when it is really a waste of resources. If its for a stationary billboard on a vehicle than it could be justified. Pete. Sometimes it just works |
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| philb Regular Member Joined: 05/07/2008 Location: United StatesPosts: 96 |
Hi Pete, I'm making a caution/warning sign for a US postal vehicle. They are slow moving throughout the country areas they cover. People tend not to see them and they tend to get slammed from behind. The strobes they use will drain a battery rapidly, then they have nothing. They also usually replace the alternator every year or so. No, I don't think I need 20 amps. 5 or the most 10 at the worst case. I'm using LEDs from Sure Electronics and a driver board from Sure Electronics Since most of them are on the road during daylight hours, a solar cell should suffice. If they are out at after dark, a cigarette lighter plug in can be used. I'm thinking this is doable. If the solar cells don't go over 36 volts, which is the upper limit on the driver board. any ideas?  philb |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Philb I can see your point now at first I was thinking as Pete was a not practical project but now I see the safety side of it. You would need an extra battery mounted in the car and a feed line to it from the power of the car with a series diode to provide power in shaded streets etc. On the solar panels I would suggest 2 x 100 watt panels at 12 volts to make the bulk of electricity. On the mounting of the panels I have mounted panels on cars and RV's using small rubber shock mounts to absorb the road shocks and the panel fitted with a foam sheet filler and back plate to absorb vibration on the cells and glass. I haven't had one fail when doing this way but seen many fail from just mounting panels without vibration proofing. A point on the shock mounts, use a three point mounting to negate torsional stress transfer to the panel, and put safety loops at each point to hold the panel in case of mount failure. Small SS cable used for sail boat rigging works well with swedges or cable clamps. From a practical point of view I feel that an extra alternator and battery on the motor would be cheaper and more practical ,as it is likely to be a relatively short term usage, as PV cells are more suited to a long term usage 10 years plus. On the leds controller incorporate a flasher with a two to one off to on ratio to make it more prominent visually and save power on the leds. In saying that I still applaud your Idea as an environmentally friendly project, but from a commercial point of view for the reasons Pete pointed out it is a bit suspect. Good luck with your project All the best Bob Foolin Around |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Ok that makes more sense. I have used the led clusters in the UV leds and they work well. They do generate a bit of heat. Have you considered using the led strips as they come sealed in a flexiable flat ribbon with a self adhesive backing. It is smd leds premounted and very bright, they are avaliable in all colours as well as rgb so you could do colour changes in the flashes. I think it would be better to still add a SLA battery and not the solar. This way you would charge the SLA from the alternator and run the leds from it, and if it went flat you still have the main battery for vehicle use as normal. You should be able to get the current draw down much lower than 5-10 amp as the leds will be pulsed and this gives a duty cycle of a on / off period. Leds dont suffer from the current inrush problem like a strobe dose, so this should also help to reduce the current greatly. Another thought would be look at some led trailer lights as these are sealled ready to mount units and also have low current requirements. Many of the brake light leds have a inbuilt flasher and strobe the light anyway. Some have high frequency pulsing which to the eye we dont see the pulse but due to the fast on/off it reduces the current by 1/2, others flash led sets in sequence to give the effect all leds are on, but in reality only some are on at any one time but the eye dont see this. What is the driver board you reffer to. Pete. Sometimes it just works |
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| philb Regular Member Joined: 05/07/2008 Location: United StatesPosts: 96 |
Hi Pete, Thanks for the ideas. The driver board is listed here http://www.sureelectronics.net/goods.php?id=1042 Hopefully it will work. I wanted to limit the current and voltage going into the LED's. The LED's I have chosen operate between 12 to 13.8 VDC. I haven't seen the brake lights with the build in strobes. If you know where I can buy them, let me know. I looked at the SMD ribbon and thought they would not be so bright. I could be wrong there.  RGB in one weatherproof unit would be ideal.
If I can be environmentally friendly while being making a safe vehicle, so much the better. Safety in this application has to come first. Bob, Thanks for the mounting tips. That is exactly what I needed. I may not use it in this application because you and Pete have about talked me out of it and into another battery hooked to the alternator. I will remember it for future use though. Normally, the mail carriers don't spend more than 6 hours delivering mail (except at Christmas)after they separate it at the post office. The second battery would probably carry the load if it is sized correctly. We will see. Now I'm off to put dual brake and accelerator controls on the vehicle. philb |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hi Phil, I did find the driver after you edited the post. The drivers would work well with something like a picaxe controlling them so it would be possiable to do flashing sequences, or running effects in the lighting. I find moving lighting sequences or flashing sequences are much more catching to the eye. I did have a hunt around fleabay for rgb strip lighting and found huge amounts listed, they are exspencive little devils but offer a wide choice of effects. I was interested in the MCD rating of them to see the brightness but found it not listed in most cases and then some said 800mcd which i dont think is right as it should be 8-10,000 at least for ultra brights. It would pay to send a question and ask the seller before buying any and if they dont know then dont buy. As it is a safety aspect you are after i think it might be best to use trailer led lights as they are made for day time use and you know they will work. There is strip lights available in these as well and might suit you needs better. I tried to find some of the flashing ones i spoke of, but did not locate them. The ones i have seen are a clear lense and i thing the tail light is only a few leds on, and the brake light flashes, its several fast flashes then a longer pause followed by several fast again. They really grab your attention. They also have a lense that helps with visability and are all weather proof sealed. You would need to mount the sureelectronic clusters in a clear casing and this would be hard as well as will knock the brightness of them. Tail lights are not cheap but will give reliable operation and are already safety approved. The current rating for tail lights in some cases are very low like 100mA which would suit your needs. Whats the dual controls for .....Back seat drivers??? 
You guys just need a good ol Aussie made vehicle, where the controls are one the Right side to start with. ( it would save having to fix a design fault)
Pete. Sometimes it just works |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Phill Best of luck with your project, and I think that Pete's Idea of the variable speed flashing is worth looking at as a fixed speed tends to merge with the background and a non flashing doesn't attract attention at all. Most of the brainless drivers with mobile phone {cell Phone} grafted to their ear need something drastic to attract their attention. All the best Bob Foolin Around |
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| philb Regular Member Joined: 05/07/2008 Location: United StatesPosts: 96 |
"You guys just need a good ol Aussie made vehicle, where the controls are one the Right side to start with." I totally agree Pete! I spent the better part of the last 3 days heating and bending metal rod to provide a brake on the right hand side. I had to go perpendiculary through to tunnel between the two front seats. There simply was no space above the tunnel. And what do I find under the right side floorboard? a brain box. So, I am making a sturdy false plate to ride over the box just to mount the brake petal and accelerator. I can imagine what would happen if someone who had too much to drink was riding there. They throw their guts up and the car dies?  Or your hunting companion has the muzzle of his rifle pointed down for transport, you hit a bump, the gun goes off and kills the car? I could have thought of at least a dozen other places to put that thing. 
"Whats the dual controls for .....Back seat drivers???" Here in the US most "back seat drivers" ride in the side seat...thank you very much. Sometimes we call them spouses too. I have asked about the MCD rating on the strips. I don't have an answer back yet. That's why I ordered the strips of 24 LED's from Sure Electronics. I also have some of them at home. The white light is mounted at head height and provides more than adaquate lighting for reading. It uses 1 watt. At a guess, I would say it would replace at least a 60 watt bulb. They claim waterproof too I think. I may try running the lights without the cover as you mentioned in you relpy Pete. Bob, I have considered the variable flash. I do have a kit for a 12 volt PWM. It can be varied by a knob. Interesting idea. "Most of the brainless drivers with mobile phone {cell Phone} grafted to their ear need something drastic to attract their attention." Unfortunately, some of them ignored a train last week too, but not for long. I don't think they knew what hit them. I do have a strong self preservation instinct from my childhood that basically states not to pick on anything that's bigger than you. I might include the word Sir when I talk to them. That said, So if the vehicle is made to look bigger... I remember Oztules refering to LED lighting he did for the island fishermen a few years back. I have looked for the thread, but have not found it yet. I remember it was very interesting and may give some insight that will help with the current project. Thanks for all your help and suggestions. philb |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Phill My Dad always said that Idiots are self eliminating no matter how much we try yo preserve them, we have the same problems here, The most dangerous sport in Australia is fishing, particularly rock fishing,that's not fishing for rocks, but fishing off the rocks, and big waves sweep them away. Pete may be able to suggest a pic axe circuit to give you a semi random flasher sequencer to attract more attention of the brain dead. All the best with your project Bob Foolin Around |
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| danielhenry31 Newbie  Joined: 29/06/2010 Location: United StatesPosts: 5 |
In the solar panels I would say 2 x 100 watts at 12 volts for the bulk of electricity. The assembly of the panels that are mounted panels in cars and RV with a rubber shock mounts to absorb road shock and filling the panel with a sheet of foam and back plate to absorb vibrations and glass cells. I have not had a failure to do so, but I saw many, not just the mounting panel without vibration testing. A point on the cushions, use a three-point mounting to cancel the transfer of torsion stress on the panel, and put security ties at each point to hold the panel if not installed. SS rope used to manipulate small boat works well with swedge or necklaces. portable battery charger |
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jkdelz Newbie Joined: 27/06/2011 Location: United KingdomPosts: 1 |
Hi all, I have a small problem here I just need a best choice for it for my project. Is it possible to run two wires from my 8A regulator output (BAT+/-) to my 20A regulator output (pos to pos and neg to neg). OR bite the bullet and run the 8A output all the way to the battery. "Not everything that can be counted counts, and not everything that counts can be counted." - Albert Einstein Solar Panels Australia |
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