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Flexible Solar Panels

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106G View Drop Down
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Post Options Post Options   Quote 106G Quote  Post ReplyReply Direct Link To This Post Topic: Flexible Solar Panels
    Posted: 26 Apr 2022 at 3:18pm
I am planning to mount flexible solar panels to the from of my Rpod. Has anyone done this? If so, what brand panels or retailer do you recommend. I would like batteries to charge while driving & keep fridge running on battery power.

Thanks,
Jack
2019 Rpod 190
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Post Options Post Options   Quote offgrid Quote  Post ReplyReply Direct Link To This Post Posted: 27 Apr 2022 at 5:37pm
As a retired solar design and reliability test engineer I recommend NOT getting any so called flexible solar modules. Solar cells are crystalline silicon and as such are not flexible. They will fracture and break over time. Also, this type of product uses a polymer (plastic) cover which will both allow moisture to penetrate as well as subject the cells to impact damage from hail, rocks etc. In addition, directly attaching a solar module to a roof is bad for both the roof and the module due to excessive heating.

Get a glass solar module with an aluminum frame and either mount it on the roof with a air space or keep it portable. It will last much longe, perform better, and you will be happier with it over time. I have designed, tested, and provided customer service for both types of product for many years and can assure you I am very familiar with them.
2015 Rpod 179 - sold - too busy playing farmer to go camping
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Post Options Post Options   Quote 106G Quote  Post ReplyReply Direct Link To This Post Posted: 27 Apr 2022 at 10:15pm
Thanks for the advice "offgrid", I am definitely NOT an expert on this subject, so your advice is helpful! i will take another look to see if I can mount a rigid panel...
jack
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Post Options Post Options   Quote offgrid Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 5:17am
You can buy roof mounting kits that attach to the solar module frame. But if you're new to solar you might want to consider keeping your system portable to start with.

There are several advantages to portability. Most important is that if you park your trailer under trees while camping roof mounted solar performance will be poor. Solar modules need to be fully unshaded to work well. A portable system on a 25 to 50 ft cable can be moved to a sunny spot.

Other advantages: you can change the orientation of the solar module to point at the sun, no holes in the roof, easy install.

Disadvantages: potential theft, more set up time while making camp, a big solar set up can be heavy to carry around.

My recommendation would be to start with a 100-120 watt portable system and see how that does for you. You can later mount that to the roof or get a second solar module and mount that permanently while keeping the original portable if you need more charging capacity.

Pretty much any glass/aluminum framed solar module will work fine. They are a commodity these days. If you get comfort by buying well known brands then that's fine too. Get one that's designed for 12V battery charging, meaning it should have a max power voltage (Vmp) of around 18V, give or take. The 18V allows for some voltage loss in the wire runs and for when the solar module is hot (solar modules actually produce more power when it's cold) while still providing the 14-15V needed for battery charging.

With that type of solar module a simple PWM (pulse width modulation) type charge controller will work fine, you don't need a more complex and expensive MPPT (max power point tracking) controller.

If you do want an MPPT controller then you will want to get a higher voltage solar module or connect two modules in series, because a MPPT controller operates by stepping the output voltage down.

Controllers are where it's worth spending a little more to get a good reliable one, they are subject to the same reliability issues as any other electronic device. I personally like Morningstar and Victron. Full disclosure, I know the Morningstar guys very well, but there is no financial affiliation. Get a controller with a current rating at least as high as the short circuit current rating (Isc) of the solar module or modules you're planning to buy.

You can run a portable system directly to the trailer battery, you don't need to use any of the "solar ready" wiring that came with the trailer. That just creates more voltage losses in the longer wiring.


Place an inline fuse matching your charge controller current rating at the positive battery terminal. The controller can be mounted by the battery too, or attached to the solar module.

Then run some heavy gauge wiring to the solar module. Since you're working with only 12V, that wire needs to be big so you don't have much voltage drop. Id recommend at least 10 gauge for up to a 30 foot run and a 10 amp controller, 8 gauge would be better and allow you to run up to about 50 feet away.

One easy way to make up a flexible outdoor rated cable is to buy a heavy gauge 30 or 50 ft extension cord and cut the AC connectors off. Don't use 120VAC connectors for 12VDC circuits, someone will eventually connect the wrong voltage and have a bad day. You can hard wire the cable at the solar end and use an Anderson type connector at the battery end.

Speaking of batteries if youre planning significant periods of boondocking then consider also installing dual GC2 6 volt golf cart batteries in series. Having the additional battery capacity will get you through longer periods of cloudy weather and have more capacity available to store energy produced on clear days so will help your solar system do a better job for you. Beware the increased tongue weight though.    









2015 Rpod 179 - sold - too busy playing farmer to go camping
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Post Options Post Options   Quote 106G Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 6:04am
Great explanation, thank you very much. I have a lot to think about. The portable system sounds great, but also thought charging while driving would be a big benefit. I have a model 190 Rpod, not sure if I have the room on roof for a rigid panel? I will have to check that out.
Jack
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Post Options Post Options   Quote Pod People Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 8:13am
we have used a Renogy 100 watt portable panel system for about 4 years.  we love the unit and have had zero problems.  It comes in a very nice protective space and is easy to handle and use.It keeps our 2 golf cart batteries fully charged if we can get at least a half day of good sun.
 As Offgrid noted, we can camp in the shade and put our panels in the sun. we have a 30' connecting cord and that has been adequate.
I usually position the panels before we go to bed in order to catch the early morning sun.  then as we prepare to leave camp for the day, I set the angle for the mid day sun. We usually return mid to late afternoon and will reset the panels for the late afternoon.  so, it really is not a big issue of having to reset the panel position.
One of the main negative factors noted about portable panels has been the theft potential.  We have never had a problem so far and neither have several of our traveling friends who also have the same type of portable system.  There have been reports of theft-but that is a chance I am willing to take in order to camp and have power when boondocking.
One other aspect of the solar picture is batteries.  we use 2 Trojan 6 volt golf cart batteries(220 amp hours each).  The golf cart batteries will take many more charge/discharge cycles, last longer and will provide more power than most any other combination except lithium. your choice of batteries can make a huge difference in your overall power system.
Good luck with your choices-check the search function for many more posts about solar, batteries and installations.
Safe travels
Vann


Vann & Laura 2015 RPod 179
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Post Options Post Options   Quote Ciberpine Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 8:53am
Here is what I did for the portable Solar:

This is working very well.  I mounted the Solar controller in the battery box on the tongue.  I have two 100 amp hour AGM batteries. 

I also installed a Victron Energy Smart Battery Protect 12/24-Volt 65 amp (Bluetooth) to protect the batteries from being discharged too much

I didn't know about golf cart batteries when I bought the two AGM batteries, or would have gone that route.  Always learning!
Scott and Noreen
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Post Options Post Options   Quote 106G Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 9:48am
Thanks, very helpful!
jack
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Post Options Post Options   Quote 106G Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 9:48am
Thanks, I am looking at that Renogy product now..
jack
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Post Options Post Options   Quote offgrid Quote  Post ReplyReply Direct Link To This Post Posted: 28 Apr 2022 at 6:11pm
Doesn't your alternator already charge the trailer battery while you're driving? If not you can run a 10 gauge wire from the tow vehicle battery + terminal through a 30amp breaker to the 7 way connector. Doing that is better than solar for on the road charging because it will charge at night or in cloudy weather.
2015 Rpod 179 - sold - too busy playing farmer to go camping
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