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 my 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) 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. 

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

I know Padraic did so, but you will have to look back in his blog many years - http://rvescapade.blogspot.com/.  

This link http://rvsueandcrew.net/ is to RV Sue's blog which has a header telling about her solar set up.  It is somewhat similar to what you are talking about.

Thanks for the replies folks!

I guess my idea might work as planned as no one has poked fun at me yet. But you know what they say, the night is still young. ;)

I'm thinking of forgoing the 12v solar system, since the trailer will be in the shade when possible, rendering the 12v solar panel on the roof useless. I'll just make the 48v system a little beefier and use the factory converter to charge my 12v batteries. It won't be as efficient, (going from 48vDC to 120vAC back to 12vDC) but if I lose say 25% of the power in the process, my 12v needs only represent 10-15% of my total electrical usage, so it's not as bad as it sounds. 25% of 10% is only a 2.5% power loss - and I'm buying simplicity and economy with this small, planned inefficiency. Plus, I'll be able to dedicate more resources (time and money) to building an maintaining one robust 48v system with a battery bank of twice the capacity than initially planned. Do you think I would need to install a switch to disconnect the converter from unnecessarily depleting my battery reserves when not needed? Or would it be OK to leave the converter draw power as it sees fit from my 48v bank? I know there are 48v-12vDC/DC converters, but they are not true chargers and won't replenish my 12v batteries with a variable voltage charging profile they need to properly maintain them.

What would you guys think about 8, S-550 Rolls/Surrette batteries (428ah at 48v) rather than 8, GC-2s? Add a couple trailer mounted GC-2s for my 12v needs, recharged by a nice 4 stage progressive dynamics converter/charger powered through an AIMS 2000w PSW inverter/charger (note the charger is for the 48v battery bank) that will normally be used to power the TTs AC outlets. www.theinverterstore.com/2000-watt-pure-sine-inverter-charger-48-volt.html Of course those 8, S-550s will add another 488 lbs to the truck, putting it near its max payload capacity when everything else (including hitch weight) is tallied.

I will have a little EU2000 Honda genny for foul weather charging back-up, just in case. As small as it is, this little generator is powerful enough to run my planned 12,000 BTU heat pump (which only draws 560 watts for cooling and 600 watts for heating) with power to spare, through the AIMS inverter/charger. www.geinnovations.net/HSAC_Productline.html

Chip

Second Chance, I will not be mounting the panels on top of the topper, but inside the bed of the truck as low as possible. However if I build the rack/topper so it is removable, I must have an inner insert which will contain the batteries. I'm thinking 4 batteries on a metal rack attached to each side (possibly right on top of the wheel wells), to stabilize it after it is removed. I just looked up the price of electric slide in truck camper jacks. I had no idea they are so expensive, so I will need to go with a set of manual crank jacks, which will suffice.

 Chip

Chip,

I built a portable rack system using a drywall lift and aluminum angle and tubing. I can lift the panels onto the truck top and roll them back as the race is on wheels. If we are staying more than a couple of weeks in one location I will take them off the roof and set the rack up towards the sun wit the proper angle to achieve maximum exposure. If we are staying short term I leave them on the truck and either use the motorcycles for transportation or I can disconnect the panels from the system at the truck. I always plan ahead if I will disconnect or reconnect the panels so that it is done during dusk or very early before sunrise so there is no power going thru them.

Here is link to our setup:

 http://s962.photobucket.com/user/mybigboomer/library/RV%20Solar%20System

Hope this helps 

Les

Chip,

Our batteries are in the front compartment of the 5er. I had considered putting them in the truck which can handle it but since most of the systems in the rig use 12v including the frig and furnace/ AC if we needed the truck we would disconnect the 12v which would turn everything off in the rig that needs it. Also some RV parks cannot handle our full rig in the same spot so although very very rarely we have to park it off site which would preclude using our 12v on board.

For us it is easier to disconnect the panels if they are on the truck.

Hope this helps.

Les

OK, here's the crude drawings I promised, so you can see what I'm talking about.



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

Thanks for your comments and criticism. They have been very helpful.

Chip

Chip, 

Looks smart! I would like to see the framing details and connections when available. 

I particularly like the Balloon tires!