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Old 08-18-2015, 12:44 AM   #1
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200 Watts solar on my A-Frame

This is something I have been planning since I got the A-128. Previously I had posted about building a custom battery box and installing a solar charge controller. I have been using two portable 30 watt panels sitting on the ground, cabled to the battery box. I've been wanting to mount some larger panels permanently to the front slope of my A-Frame. I have finally got around to it, and took the new setup boondocking this weekend.

First, I welded up two mounting bars. Here is a photo of one finished and painted, and the other one ready for paint:



Ok, now here are the two panels mounted on the racks, ready for placement on the trailer:



Here is the trailer at camp showing the panels mounted:



Here is a closer view of the panels mounted on the front slope: I used marine 10 gauge duplex cable (white sheath) to run the solar current to the battery box. I used some leftover 3M Extreme Sealing Tape to stick the cable down on the fiberglass. I didn't want the cable flapping and beating on the fiberglass while running down the highway. I also zip-tied the black solar panel cables to the solar panel frames to keep those cables from flogging the fiberglass as well.



Next is a sideways detail shot. Lag bolts attach the racks to the side of the roof through the aluminum roof frame. The racks have clearance to the fiberglass panel because of a little natural sag in the fiberglass between the aluminum roof frames on each side.



With permanently mounted panels, I needed a way to disconnect the solar charge current from going to the charge controller when the battery is disconnected. The charge controller is not happy getting solar power if the battery is not connected. So the sequence for powering up is 1) Connect battery power to the trailer using the master battery cutoff switch (red flag thingy); 2) Flip up the solar current switch to send solar power to the charge controller. Power down in reverse, first turning off the solar charge current switch, then the master battery cutoff switch. Also when the trailer is connected to the vehicle, I turn on the master battery switch, but leave the solar charge current switched off. I don't know what effect sending solar power backwards to the vehicle voltage regulator will do. I think not good things.



And finally, here's a picture of successful solar boondock camping:



Next enhancement: A DC compressor driven refrigerator like this one:
Amazon.com: Dometic CFX-65DZUS Portable Freezer/Refrigerator - 2.2 cu. ft.: Automotive

I now have the power generation and storage capacity to run one indefinitely.
Enjoy!
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Old 08-18-2015, 01:05 AM   #2
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Lighted Canopy

Oh yeah, one more bit of 12 volt coolness: See that canopy? I installed an exterior 12 volt cig socket outlet on the outside of the trailer near the factory AC outlet. Then I built a 16 foot long cable made of low voltage landscape cable that goes under my entry rug to the canopy. Hanging from the canopy are four 12vdc LED light bulbs. The exterior power socket is switched from inside the trailer. So I can turn on or off the canopy lighting from inside the trailer! I'm having too much fun with this stuff, I'm telling you!

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Old 08-18-2015, 07:28 AM   #3
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Dan-

Amazing and very cool outfit you have come up with. Thought of coming up with a semi-hard cover for the panels yet? This would stop energy production when traveling and also protect panels from road debris. I've got the Renogy 100W solar suitcase and love it. Versatile and has been able to produce enough power to keep me going.
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Old 08-18-2015, 11:08 PM   #4
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Hi 61cubby,

No I had not thought of that. I don't think that the panels are vulnerable, and with the solar power stopped at the switch, I don't see a need to to cover them to keep them from generating power. When you say semi-hard covers, that means that I would have these large "things" to manage at camp when they are off the panels. I guess they could be stowed underneath the trailer while camping, but again, I don't think that's necessary. Thanks for the thought though.

Let me mention that I have my two 30 watt panels hinged together and I built a thin plywood box to house, protect, and transport them. Folded up and in the box, it is much like the Renogy suitcase panels that you have. A buddy of mine just got the 100 watt Renogy suitcase panels. He and I built a 35 amp-hour portable power pack from a large plastic ammo can. He's a tent camper and he needs to run a CPAP machine, so this portable system lets him do that.
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Old 08-19-2015, 07:30 PM   #5
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Nicely done. My only thought is that the panels could of had a pivot point on the upper side with fixed or extendable legs on the lower side making the panels adjustable so that you wouldn't have to park the same way every time you camp....DAMHIKT

GW.......facing east!
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Old 08-19-2015, 07:54 PM   #6
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Just curious, why didn't you connect the panels in series rather than parallel? That way you would not need the multiple connectors AND you would have higher voltage and less amperage which requires much smaller wiring and less current loss.
You can leave the system connected to the batteries, assuming you are using a solar controller as it will not allow voltage "back into the regulator". I never turn mine off. If the batteries need charging, they get it, either from the TV, converter when plugged in or from the solar panels. The controller acts as a diode to the system.
I hope you have breaker switches between the panels/controller and batteries/controller. They act as fuses and/or on/off switches.
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Old 08-19-2015, 09:58 PM   #7
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Quote:
Originally Posted by GeeDubb View Post
... the panels could of had a pivot point on the upper side with fixed or extendable legs on the lower side making the panels adjustable so that you wouldn't have to park the same way every time you camp
You're right that for best power production I need to point the front of the trailer due south when I park. Your suggestion would allow the panels to be adjusted for optimum angle if I camped in radically different latitudes, but I would still have to park pointed due south ... unless I went to Australia I guess. Then I would have to point north!

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Originally Posted by Blackhat6mike View Post
Just curious, why didn't you connect the panels in series rather than parallel? That way you would not need the multiple connectors AND you would have higher voltage and less amperage which requires much smaller wiring and less current loss.
Because I have a PWM controller, not a MPPT controller that can perform the 24V to 12V DC-to-DC conversion. The PWM controller I have CAN accept 24V solar input (which is actually in the high 30's of voltage), but then I get 24V output which does me no good to feed a single (but large) 12V battery.

Quote:
Originally Posted by Blackhat6mike View Post
You can leave the system connected to the batteries, assuming you are using a solar controller as it will not allow voltage "back into the regulator". I never turn mine off. If the batteries need charging, they get it, either from the TV, converter when plugged in or from the solar panels. The controller acts as a diode to the system.
Well, I really didn't know what effect backfeeding power on the charging line from the vehicle would have on the vehicle's voltage regulator. Maybe that's OK, but since I didn't know, I figured that was an experiment that I didn't need to try ...

Quote:
Originally Posted by Blackhat6mike View Post
I hope you have breaker switches between the panels/controller and batteries/controller. They act as fuses and/or on/off switches.
I have fuses - which aren't fun to use as switches.

Thanks for the replies!
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Old 08-19-2015, 10:39 PM   #8
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I think you will find that the controller takes the voltage in from the panels and converts it to the correct voltage of the batteries be it 12 or 24 VDC. Two 100 watt panels in series will produce a max of 44 volts if working at 100%, which they never will except on paper. Your PWM controller should be good for 100 VDC if my memory serves me well.
There is a huge difference in the efficiency between the PWM and a MPPT controller, thus the difference in price. I went down that road when I first started my solar system. I now have 600 watts, 3 panels in series then paralleled to the other 3 in series. My max voltage reaches 63 volts and at times, up to 12 amps, just not both at the same time.
I think you will find the MPPT controller actually do produce as much as 30% more juice than the PWM. If you are only using one battery, that will make a difference. I have 500+ amp hrs of batteries so I need all I can get. JMHO
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Old 08-19-2015, 11:19 PM   #9
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Thanks mike,

I understand that an MPPT will be more efficient. But an A-Frame is but one step above a tent, it is not a house like your rig! 200 watts and 200 amp-hours on PWM is a balanced and adequate system for my humble little portable cabin in the woods.

I just double checked my controller's spec sheet, max input voltage is 40V. You might be right that it will down convert panels in series to 12V, but if it does, it will do that by PWM chopping the high voltage down to the three stage charge voltages. That means that it would waste even more power since it cannot do the DC to DC conversion to increase amps while decreasing voltage, as an MPPT will do.
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Old 08-20-2015, 09:15 AM   #10
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That is some nice work, and

I appreciate your sharing it with everyone.

My only concern is the amount of tongue weight that is added from everything.
I am sure your tow vehicle can handle it, but maybe the new tongue weight is a bit much for some tow vehicles.

Happy camping!
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