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Has anyone ever mounted solar panels to a tow vehicle?

sushidog
Explorer
Explorer
I want to build a rather heavy solar system for full-timing in a travel trailer (actually 2 separate systems, a 12v and a 48v one). However finding TTs that will carry this much weight are hard to find and limit my choices considerably.

I was just toying with the idea of mounting some high voltage solar panels and 48v battery bank on a pick-up truck rack over my bed topper. As a side benefit, the panels would act as a giant wind deflector, increasing fuel mileage when towing. I would mount 4 - 435 watt Sun e20 panels on the rack at a 9-10 degree angle to deflect wind over the top of the camper while towing. I could also hinge the front to lift them to a higher angle into the sun when stopped (possibly with an electric jack.) Another advantage this would give me is I could park the camper in the shade, in the best direction that suits the location, while the truck could be positioned where it would collect full sun. If I use the 435 watt Sun panels, they would overhang the sides of the truck by about 4" on each side and about 8" in the back. If I use the smaller 300 watt Sharp panels instead they would fit with only a couple inches overhang either way, but probably wouldn't deflect the wind quite as well as the bigger panels would. If the 300 watt panels are used, I would need to add 2 folding panels, (for a total of 6 - 300 watt panels or 1800 watts vs 4 - 435watt panels for 1740 watts) one on each side, which would hang vertically when traveling and be raised so they are flush with the others stopped. I would have the charge controller and inverter in the truck bed, near the battery bank. An 8 ga heavy duty 25ft extension cord should be more than enough to carry 12 amps of 48v DC power needed to power my 48v native mini-split heat pump. I would also add a 30 amp female electrical receptacle mounted on the back of the camper to plug my trailer's shore power cable into for my inverted 110v AC needs. Another advantage of my plan, other than to remove about 900-950 lbs of weight off the trailer, (at the expense of 1,000 lbs added to the bed of the truck, which should be OK as I have a 3/4 ton with enough reserve) would be to allow easier access to the solar panels for cleaning and maintenance without climbing on the roof of my TT. Plus the additional weight and expense of building a tilting solar panel rack will be offset by the cost and weight savings of having fewer solar panels producing higher output due to tilting.

Here's a drawing of what I'm talking aout:


Has anyone seen or done something like this? Does anyone see any major drawbacks in my plan?

-Summary-

Advantages:

1. Removes 900-950 lbs from the trailer.

2. Starts with 10 degree panel angle (great for RGV in summer) and allows easy panel tilting for harvesting more solar power, especially in winter and higher latitudes.

3. Facilitates panel cleaning, and battery access - lower is safer

4. Allows panels to act as big wind deflector making towing easier and improving mpg.

5. Panels shade truck and topper, keeping it cooler inside.

6. Travel Trailer can be parked in the shade (or mostly so) so it stays cooler inside trailer, requiring less AC.

7. Truck can be easily positioned for maximum solar harvest at different times of the day and year.

8. Avoids putting extra holes in roof of TT to mount 4-6 panels (plus saves roof space).

9. Increases storage space inside TT by moving batteries, controller, meter and inverter to truck bed.


Disadvantages:

1. Adds 1,000 lbs to the truck which will reduce MPG when not towing. (Will offset MPG gain when towing)

2. Takes up some additional space in truck bed to house batteries, controller and inverter.

3. Any more?

Thanks for your help and advise,

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis
35 REPLIES 35

allen8106
Explorer
Explorer
RV Sue mounted a solar panel on the top of her van and has the battery box in the back of the van. Google RV Sue and you can read about her solar set up. She travels exclusively in the west from north to south staying about 90% of the time in boondocking areas.
2010 Eagle Super Lite 315RLDS
2018 GMC Sierra 3500HD 6.6L Duramax

2010 Nights 45
2011 Nights 70
2012 Nights 144
2013 Nights 46
2014 Nights 49
2015 Nights 57
2016 Nights 73
2017 Nights 40
2018 Nights 56
2019 Nights 76
2020 Nights 68

sushidog
Explorer
Explorer
Buuta4, you bring up a good point. Since they are mounted very high, I think they might be too high to be damaged from flying rocks, but bugs are another matter. While they are hail rated to take quite an impact, especially if the angle if incidence to the impact is only 10 degrees, (unlike a windshield mounted at about 70 degrees) I'm not worried about them breaking or even chipping from rocks, but I will need to watch for low hanging limbs (though this is no different than if they were roof mounted,) They will need cleaning more often than panels mounted at zero degrees, but cleaning them will be much easier than roof mounted panels, especially with the angle which will allow water to run off more easily than a flat panel. Alternately, I could mount them absolutely flat, flush with the cab of the truck during travel. However this would necessitate building a lower topper which would prevent me from being able to ride my 2 motorbikes into the bed.

I could cover them with a canvas or nylon cover during transport. Though they would stay cleaner, the flapping and chafing of the canvas might cause scuffing of the glass and be worse in the long run than simply cleaning them a little more often. Plus the canvas would prevent collecting sunlight during the time the truck is in use.

I think many people envision the panels at a 30 degree angle, however I will be dealing with a 13.6 ft. length of panels making the angle to the wind very small. I'm just using 10 degrees as a max estimate, however I think the angle of attack will actually be more like 8-9 degrees once the precise measurements are taken. For instance, a 2 ft rise over the cab in the rear would equal an 8.5 degree angle. I would have to go 2' 5" over the cab to make a 10 degree angle, which is more than I think will be needed.

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

buta4
Explorer
Explorer
Maybe I'm overly cautious but, using solar panels as a wind deflector might introduce them to road damage from sand, pebbles, etc. hitting them.

Over a long period of time, might the solar panel performance be degraded from that type of exposure to road debris?

Just sayin'.
Ray

sushidog
Explorer
Explorer
Thanks for the feedback Wes. My slide on camper will really be just a camper shell that rests on the sides of the truck bed. My idea of mounting them centrally is so they act like a ballast to prevent tipping in high winds, centralizing the weight more or less evenly on the topper's legs when off the truck. If I slid them more forward, then the cabling would be longer and most of the weight would be to the front of power pod. The solar panels will overhang the top of the supercab, extending about 5 ft forward of the topper. The purpose of mounting the inverter and controller to the rear (other than to reduce the wire run is to offset some of this forward weight. Plus when the solar panels are angled higher, say in the winter at higher latitudes this will shift even more weight forward as the panels will hinge at the front of the topper.

I am trying to design the power pod structure as lightweight as possible while still retaining its strength to hold the 200lbs of panels on the roof. think I will design the front jacks so they can be removed for traveling. I would like to find jacks with the longest possible travel, so I can lower the pod close to the ground when off the truck, to make it more stable and easier to clean and adjust the angle of the panels. I would also like to mount large locking swivel jack wheels (like on a trailer tongue jack, but lockable like casters on a tool box) to the legs to make it easier to position when off the truck. Say something like this but with a lock: http://www.greenlee.com/products/CASTER%2540cSWIVEL-ALL-TERRAIN-10%2540andquot%253b.html or this: http://www.durablecasters.com/pdf/series-67-68-pneumatic.pdf

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

Wes_Tausend
Explorer
Explorer
sushidog wrote:
Here's my first draft of the walls with component layout.

Suggestions for improvement?

Chip

Chip,

It seems the interior of the "cabin" will be useful for additional storage purposes other than batteries. In that regard, the batteries might be secured under some sort of removable flooring.

The picture shown indicates that batteries may be located between the inner fender wells of the truck box. I wonder if they wouldn't work better ahead of the rear axle near the front of the box. Part of their weight would then be distributed to the front axle leaving the rear axle more unloaded for accomodating trailer tongue weight and other temporary camp items.

It's a great project, giving you a valuable storage shed at your campsite along with a handy portable power station.

Wes
...
Days spent camping are not subtracted from one's total.
- 2019 Leprechaun 311FS Class C
- Linda, Wes and Quincy the Standard Brown Poodle

sushidog
Explorer
Explorer
Here's my first draft of the walls with component layout.



Suggestions for improvement?

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

sushidog
Explorer
Explorer
Here are a couple drawings to illustrate my plans.



I'll do one of the interior framing with controller, inverter, battery and shelf placement another day, once I collect my thoughts.

Thanks for all your comments and criticism. They have been very helpful. ๐Ÿ™‚

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

brulaz
Explorer
Explorer
sushidog wrote:

...
What I could do is make a droppable solar/power pod with powered retractable legs, like a slide in truck camper uses. This would allow me to optimally position the solar panels in the sun, facing south, while allowing me unencumbered use of the TV if I desire.
...


Now *this* is a great idea.
2014 ORV Timber Ridge 240RKS,8500#,1250# tongue,44K miles
690W Rooftop + 340W Portable Solar,4 GC2s,215Ah@24V
2016 Ram 2500 4x4 RgCab CTD,2507# payload,10.8 mpgUS tow

pianotuna
Nomad III
Nomad III
Chip,

They are not sold online. Because they are not starved acid AGM they behave a bit differently. They are a little more tolerant of not being returned to 100% state of charge. Accent the word LITTLE. It is still best to get to 100% as often as humanly possible.

I'm very much looking forward to not laying on the ground to check electrolyte levels.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

sushidog
Explorer
Explorer
Thanks for the lead on the Telecom batteries. If they have 80-90% of their design life left then they are a very good deal indeed. Yes maintenance free AGMs are superior to FLAs, with lower internal resistance. They charge more efficiently (less solar power wasted) and faster. They also discharge deeper with less of the Peukert effect, making more of those 278ah (for a 48v bank of ๐Ÿ˜Ž usable. The big hang-up with me was price, (as they are typically 3 times FLAs) but these look like a great value. I looked for them on the Interstate Batteries online store and couldn't find them, so I guess I'll have to check with my local store when I'm ready. It will be about 3 years till I'm ready to buy so I still have plenty of time - just doing a little advanced planning to see which direction I need to go. It's good to keep them on the radar though for when I'm ready to plunk down my cash.

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

pianotuna
Nomad III
Nomad III
Just because you have a big inverter does not mean you have to use all of it. I've seen a draw of 276 amps on my 3k Magnum. That happened during testing and I did not realize I had the water heater on while running the fridge, and the roof air conditioner.

The telecom batteries I got at the Interstate store and the come with a 6 month warranty. They are 12 volt @ 139 amp-hours.

Because telecom requires 100% reliability the batteries are changed out on a yearly basis. They are a 10 year design life with a 3 year warranty. The chances are mine have only been in service for one year and that they have never been deeply discharged.

I was going to spend over $3600 for Surrette batteries. The telecom's will come in at about $480.00 Even if they only last 2 years I'll be money ahead. I've managed to get ten years out of my Marine Walmart flooded batteries.

Because they are an AGM variant they may exhibit far less voltage drop than golf cart batteries. They can also be recharged at the C/5 rate.

I could have gone with six jars but for now I'll do just four. They will be installed either next Sunday or Monday.

If you go with 48 volts you could have 2 banks of 4 each with simple switching for selection.

sushidog wrote:


Where does one shop for used telecom batteries, and do they come with any guarantee? If I went with 8, 139ah 100lb telecom batteries (wired series and parallel as I assume they are 12v) that would still be 800 lbs of batteries for 278 AH (.35ah/lb), vs 8, S-550s at 984lbs for 428ah (.43ah/lb) though at higher cost. How long can I expect used Telecom batteries to last? I'm sure they are replacing them because they are old and have lost much of their life and capacity, right?

The heat pump runs on native 48v DC drawing 11.5 amps to make 12,000 BTUs of cooling and 12.1 amps for 12,500 BTUs of heating. http://www.geinnovations.net/HSAC_Productline.html I'm looking at the HSAC-12H/C model. This type of AC uses a low-head rotary compressor that scales back its output and current draw based on need. It doesn't cycle like a normal piston compressor so no high current surges are required for start-up. Assuming it runs at full power continually, (an unlikely occurrence) and does not scale back current draw a 200ah bank of golf cart batteries would allow it to run over 8 hours (all night) before the batteries drained to 50% capacity. However with an inverter using considerable battery power, the larger 428ah Rolls bank would be ideal, especially in bouts of bad weather when there is incomplete solar charging. During the day, an elevated 1740 watt solar bank (25+ amps) should be enough to power the AC for several hours during the day as well as at night, without too much power management (reduction of consumption) in other areas.

Like your valid argument against the AIMs inverter, favoring the more durable Magnum - I'd rather pay 3 times as much for new 10 yr Rolls batteries than for ones with 35% less capacity and uncertain life expectancy.

Chip
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BenK
Explorer
Explorer
Here is where I'd love to have for my TV...and where am noodling
where to mount the batteries...

Pulling Hills: Torque vs. Horsepower
electrodynamics dynamics electricmotor dcmotor 1,500hpcontinuous


Now that sodium-ion batteries are no longer just a prototype and
into development...am hopeful they will be commercially available
when I get to this dream of mine...
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

sushidog
Explorer
Explorer
CA Traveler, I did the math and at a 10% angle of attack, the wind load at 115mph is about 15% of what the panels are rated for, so wind load is not an issue.

What I could do is make a droppable solar/power pod with powered retractable legs, like a slide in truck camper uses. This would allow me to optimally position the solar panels in the sun, facing south, while allowing me unencumbered use of the TV if I desire.

Thanks for the ideas folks. Keep em' coming! It is causing me to think outside the box and improve my plans.

Chip
1999 National Tropical
Triton V10, Ford F53 Chassis

BenK
Explorer
Explorer
Boils down to 'decisions' and 'compromises' that all designers/engineers must make

The solar array will 'shade' the trailer and if you have an air gap, the temp
differential will be or should be high enough to keep the trailer cooler in full
sun. The sides will then become an issue, but that goes back to
the 'decisions' and 'compromises'...

That 1K of batteries is always a problem for storage on mobile vehicles

If the TV has more payload capacity, then there...or a bigger or different
type of architecture of trailer...toy hauler maybe?

CDR's (Critical Design Reviews) should not be personal and I do NOT or am NOT
dissing this

One of my design philosophies is to ask everyone, including myself, to toss
stones at mine or teams design until the stones bounce off and/or the breakage
is acceptable...
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...