Author Topic: Solar Powered Trailer Lighting?  (Read 16217 times)

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Offline donpearsall

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Solar Powered Trailer Lighting?
« on: June 29, 2011, 11:16:45 PM »
I have been thinking about putting LED light fixtures in my trailer for interior lighting. LEDs are pretty low wattage and the prices are coming down. I could power them with a 12v car battery that is charged by a solar panel on the roof of the trailer, and then also charged when hooked to the truck. Of course the solar panel has to be weather proof. And it would not be 100% efficient since it would not always be oriented to the sun.
Has anyone done this? Any tips?
Thanks
Don
550 hp 2003 Suzuki Hayabusa Land Speed Racer

Offline johnneilson

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Re: Solar Powered Trailer Lighting?
« Reply #1 on: June 29, 2011, 11:39:08 PM »
Make sure the solar panel has a diode to prevent discharging the battery. It won't take a big battery to power the lighting.

I used to store my trailers with a portable solar panel. I just made up a receiver connector and plugged in the trailer to the panel hanging on the fence.

 
As Carroll Smith wrote; All Failures are Human in Origin.

Offline hotrod

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Re: Solar Powered Trailer Lighting?
« Reply #2 on: June 29, 2011, 11:39:15 PM »
Are you just looking for enough light to keep from tripping over stuff, or enough light to do work by?

Those small touch lights that they sell for use in closets are LED lights running off of 2 to 4 AA batteries. They will run literally for a week continuously on one set of batteries. Walmart has some cheap led lights with about 10-20 LED's intended for camping that run on 4 AA batteries that provide enough light to do work that does not demand really bright light.

If you bought a few of those cheap LED touch lights and wired them in series to a 12V gel cell they would run for several weeks continuously on one charge. You can buy a small 5 watt solar panel from Harbor Freight for about $60 that would work to charge the gel cell.

For close work that requires really good lighting like final engine assembly and inspecting spark plugs etc. you would need several of the LED fixtures to have a bright work light environment. The one problem with the bright white LED lights is that they are not a true broad spectrum light source so it is difficult to judge colors with them. I use them for general emergency lighting, and a single 3 LED lantern from Walmart intended for camping will provide enough general illumination for moving about safely but not quite enough to work by.

I would suggest you pick up a couple of the LED touch lights and one of those large LED lights for camping and see if they provide enough light for your needs, and  how you like the character of the light.

You can also buy small florescent tube fixtures designed to run on battery power that in my opinion give a better (true white) light than the bright LED's. I personally find the bright white LED's a little bit harsh in the character of the light they produce. I have 2 of the small florescent fixtures that run on AA batteries that I use for working on computers, they make them in 6" long and 12" long designs which work great to see what you are working on inside a computer case. They could also be wired to run off of a 12V power supply by rigging up the proper supply voltage or wiring them in series so the total voltage required for the set is 12V.

Once your eyes get dark adapted it does not take much light to do general work so the best way to judge how many fixtures you need is to actually test a couple of those cheap touch lights inside the trailer at night. In the day time out on the salt the exterior is so bright that most any light will seem dim by comparison, so you might actually need more lighting during the day time on the salt than at night because your eyes will be accommodated to the outside light levels.

The one advantage of the small touch lights is  you can put them exactly where you need the light, rather than try to illuminate the whole trailer interior to suitable light levels.

Painting the walls and roof of the trailer interior white will help a lot!!
« Last Edit: June 29, 2011, 11:48:52 PM by hotrod »

Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #3 on: June 30, 2011, 07:37:48 AM »
Have you done much searching for the solar panel and associated equipment (regulator, diode stuff, and so on)?  I have -- and found it isn't a cheap way to get electricity.  I was looking for a 12VDC system - to run some 12-volt equipment in the trailer.  Not lighting -- radios and other low-current stuff.  But I figured about 60 watts would be needed from the solar charging system.    Assuming about output 50-60 percent of maximum capacity (averaged over a 12-hour day, just because I had to choose some basis) -- I'd get about 30-35 watt/hours x 12 hours = about 400 watt-hours in a day.

The equipment that I want to power will draw abut 100 watts total, so I'd use all of the solar power and more than that amount again from the battery's reserves each day.  A few days of this -- and I'd have to run the generator for a day or so (@ 8 amps DC output) to top off the battery again.

And now - why 60 watts from the solar system?  Because that's a common output size in the world of solar arrays.  Even though common - it isn't cheap.  I found that it'd be on the order of $400 for the basic stuff - not including the battery or the mounting equipment on the roof or the wiring.  I can run the generator for one heck of a lot less than that each day.  I'd lose the silence of the solar - I'd gain the much higher output to serve my needs.

This, I know, doesn't answer your question with regards to a light source.  But it does give you an idea of the costs involved for a different watt-hour requirement.  LEDs might be able to live with 35 watt/hours from the solar device -- but you'd need a big bunch of them to give you lots of light.  I don't think that fluorescent lamps will give you enough light on this power budget - so you might need to spin up the generator now and then to get the battery back to where it needs to be.

I really wanted to run the trailer on solar -- but it isn't going to be cost-effective at this time.
Jon E. Wennerberg
 a/k/a Seldom Seen Slim
 Skandia, Michigan
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Offline jimmy six

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Re: Solar Powered Trailer Lighting?
« Reply #4 on: June 30, 2011, 11:07:22 AM »
I keep one of those small solar chargers on my trailer year round while it's stored to keep the battery up. At the salt I use the 12v supply for the CB and regular radio. I've never had a problem at the end of the week using the winch or lights.......Good Luck
First GMC 6 powered Fuel roadster over 200, with 2 red hats. Pit crew for Patrick Tone's Super Stock #49 Camaro

Offline donpearsall

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Re: Solar Powered Trailer Lighting?
« Reply #5 on: June 30, 2011, 11:44:37 AM »
Thanks for the replies and ideas everyone. I see that Harbor Freight has a 45 watt solar panel kit on sale now for $169. That is more than I need but the price is right. Will that work for you Jon?

Don
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Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #6 on: June 30, 2011, 11:45:26 AM »
JD, do I understand that you run the CB and broadcast radio off the battery (that's kept full by a solar panel) all week?  Is the solar thing charging the battery?  Does quality of the CB and radio degrade as the battery gets low on charge -- or are things still fine (as you say)?

I expect to have quite a bit more load -- CB, two broadcast radios, laptop computer, and probably another few items -- totaling 8 - 10 amps of the 12VDC.  I don't want the voltage to go down enough for the equipment to suffer from low voltage, but maybe a solar unit would be able to stave off the need for the little generator.  But -- as I said, 60 solar panels cost in the hundreds of dollars.  I can buy lots of gas for the generator - but will have some noise.  Worth the trade-off?
Jon E. Wennerberg
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Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #7 on: June 30, 2011, 11:46:19 AM »
Now I see your note, Don.  45 watts would be a help -- and I'll look at H F's catalog and see what I find.  Thanks.
Jon E. Wennerberg
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Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #8 on: June 30, 2011, 12:01:08 PM »
Don, would you please send me the page from Harbor Freight showing the $169.99 price?  My 'puter comes up with $179.99.

http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html

Hey, ten bucks is enough money to - to - to buy at least a hamburger and Coke.
Jon E. Wennerberg
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Offline hotrod

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Re: Solar Powered Trailer Lighting?
« Reply #9 on: June 30, 2011, 12:46:09 PM »
With photovoltaic panels they generally assume that you get full rated power (full sun conditions) from approximate 10:00 am to 2:00 pm and degraded output for a couple hours earlier and later in the day. (assuming you are not tracking the sun with the panels but place them in a fixed location looking due south. That works out to being able to expect near full rated power for 6 hours a day under cloudless conditions.

The power out is directly proportional to the illumination levels on the panels, so in some special cases you can actually get more than rated power. For example I had a solar panel test bed I set up years ago to figure out how much power I could get from cheap surplus panels available at the time from Gateway Electronics, and I closely monitored charging current through out the day and found that when the panel was in full sun but a large cloud was near the sun, but not obstructing it, the scattered light from the cloud added to the illumination of the panel enough to noticeably increase charging current. On most panels power out drops sharply if any part of the panel face is shaded, so you want to keep shadows off the panel face.

Out on the salt flats you have an infinite reflector in the form of the salt which if they are getting a lot of scattered light from the salt, during mid day they should exceed rated power out.

The normal recommendation is to angle the panels at the local latitude - 15 degrees. For Bonneville that would be  about 40-15=25 degrees above the horizon for the optical axis of the panel. If you moved the panels east - west 2 x during the day you could extend that full sun period another hour or so.

I have used one of the 5 watt harbor freight panels on the car battery to keep from running it down while using my lap top intermittently and occasional use of the CB and car radio. I don't have any test numbers for actual power out.

The other thing to consider is the duty cycle of your power use. It might be cheaper over all to use a larger battery pack on a small solar panel so you had more reserve capacity. On my ham gear at home I have 2 deep cycle 12 v batteries on a trickle charger and if I lose AC power they will run the radios on receive with occasional transmissions for about 24 hours. In most situations you will have long periods of partial sun where you are not using any power early in the day and late in the day for the panel to recover the battery charge.

You will need to audit all your power demands to figure out how much actual watt hours you need per day and size both the solar panel and the battery pack accordingly.

Larry

Offline manta22

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Re: Solar Powered Trailer Lighting?
« Reply #10 on: June 30, 2011, 12:47:57 PM »
Our new Costco store here in Tucson is selling two types of solar panels-- a polycrystalline 220 watt panel and a smaller thin film panel. The 45 watt Harbor Freight solar panel is a thin film type.

Thin film solar panels are cheaper but have much shorter lifetimes than a polycrystalline or monocrystalline panel. The latter two types are typically at least 80% after 25 years while thin film panels start to lose efficiency after about 5 years.

Check out Amazon.com; they also sell solar panels of various sizes.

Regards, Neil   Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #11 on: June 30, 2011, 01:04:07 PM »
Thanks for the lifetime estimates, Neil.  In my case I assume it wouldn't be an issue -- because I don't expect to use the panels more than 5 - 6 weeks/year.  I've got a deep-cycle battery in the trailer - and the battery stays charged enough all winter long that I can use the 12V lights in there -- with no trickle charger or anything.  If I do elect to go with a solar array I'll likely add another battery to the trailer, which'll give me twice the reserve power.  That ought to eliminate worries about the voltage sagging as the day goes on and the sun goes away.  I could cheat a bit by hooking up the trailer wiring plug to the pickup since that way I'd be drawing off the dual batteries in there.  But -- I can stay hooked and drive to the line at the same time. :roll:
Jon E. Wennerberg
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Offline donpearsall

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Re: Solar Powered Trailer Lighting?
« Reply #12 on: June 30, 2011, 07:52:55 PM »
Jon, the $169 price was from a flyer that I get mailed to me. Today was the last day of the sale. BUT on July 4, they have a 25% off everything sale.
Don
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Offline Seldom Seen Slim

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Re: Solar Powered Trailer Lighting?
« Reply #13 on: June 30, 2011, 08:59:34 PM »
Thanks for the 4th of July tip, Don.  I'll look forward to it - shipping costs and all.  By the way, this is being sent AFTER I sent an email back to you a few minutes ago.

Have a safe and happy Fourth of July, buddy.
Jon E. Wennerberg
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Offline thundersalt

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Re: Solar Powered Trailer Lighting?
« Reply #14 on: June 30, 2011, 09:13:20 PM »
Here's a goog online solar source I have used.http://store.sundancesolar.com/
Also, be sure to run a charge line from your tow vehicle.
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