When you do (and don’t) need portable solar panels

Solar power is one of the most confusing topics for RV travelers in general, and it really shouldn’t be. It’s simple technology that adds free power to your Airstream’s batteries and it just works. For most people, it’s the obvious choice for extending their off-grid camping time.

The big advantage of using solar power is that once you install the hardware, there’s no ongoing cost or maintenance. When the sun shines, power flows into the batteries. You don’t have to flick a switch or remember to do anything.  The system turns on automatically when the sun comes up, and it goes off when the sun goes down or the batteries are full.

Since solar is also silent, it’s great if you like to camp in quiet settings and don’t want to hear a generator running for hours.  And it does a better job of charging batteries than a generator.

If you’re thinking solar is for you, your next choice is whether to install fixed solar panels on the roof or get portable solar panels that you can deploy on the ground. Let’s look at the advantages and disadvantages of each:

FIXED (ROOFTOP) SOLAR

  • Complex installation, usually done professionally
  • Holes drilled in your Airstream
  • Bigger theoretical capacity usually compared to portable panels (200-400 watts depending on rooftop area)
  • Permanently set up
  • Power collection happens anytime, even when towing or in storage
  • Won’t collect power if the trailer is parked in shade
  • Panels can’t be oriented to the sun

portable solar panels deployed in front of Airstream

PORTABLE SOLAR

  • No installation required, just plug and play. No holes drilled in the Airstream
  • Typically less capacity than rooftop solar (120-200 watts)
  • Some setup required (a couple of minutes)
  • Can’t leave it set up while in storage or when towing
  • Can collect power when the Airstream is in shade
  • Panels can be easily oriented to the sun to optimize effectiveness

Sometimes people ask if they can have both rooftop solar and portable solar. The answer is generally “We don’t recommend it” unless the system is designed that way from the outset. If purchased separately, each system will come with different panels and charge controllers. The panels need to be matched (all the same) and two charge controllers will confuse each other, so if you’ve already got rooftop solar, you will not get the best results by trying to augment it with a portable solar kit.

When people install rooftop solar on an Airstream they usually go big, putting up as many panels as will fit on the roof. This helps compensate for the fact that the panels are fixed in position (facing straight up) and can’t point at the sun when it is rising or setting. But in this case you’re paying for a fairly expensive solar array that isn’t producing as well as it could.

That’s exactly why our Portable Solar Kit can perform as well as a much bigger rooftop system. The lightweight panels can be pointed directly at the sun no matter where it is—down low on the horizon, or hidden behind trees—because you can tilt, orient, and move the panels to be where the sun is.

In addition, our Portable Solar Kit uses a very high quality Merlin panel that has thousands of “interconnects” in each panel, many more than traditional panels. That means the panels are less affected by a bit of shading, say, from a leaf. The net result of this and the ability to move the panels to point at the sun means the 160-watt Portable Solar Kit can yield as much power as a significantly larger rooftop array.

Bottom line

If you don’t want to have to deploy a portable array each time you need it, or you need your solar panels to be producing all the time, rooftop solar may be for you. If you want the maximum power for your buck, maximum flexibility, and only need solar occasionally, portable solar will probably work better and save you money.

Comments

    • RichLuhr says

      This can work, but only if the controllers have the same charging profile, and the solar panels have the same output voltage. For most people adding portable solar after having already installed rooftop solar, this isn’t the case. When it does, as in your situation, it’s awesome!

  1. Tom Feury says

    Thanks for this Rich.
    My 2017 FC27 also has 160 watts on the roof (zamp I believe) and the zamp connector on the hitch to add a portable. Zamp told me that I CAN add their portable and they WOULD work together. I added a 230, and they SEEM to work together, but without appropriate testing equipment, it is hard to tell. I am getting 2 new 12V AGM’s this winter, time will tell I guess.

    • RichLuhr says

      Yes, since your system is all one vendor, it’s possible to match everything so that portable + rooftop can work. But I would think you might want to consider adding battery capacity. 390 watts of solar capacity is a lot for two typical Group 24 batteries.

      • Tom Feury says

        thanks for the advice. I will look into what it would cost to add a couple more batteries. I also thank you for the great advice and products you offer. I have made good use of them all!

        • Jerry Phillippe says

          You might also consider a couple other items. The 2017 AS’s came with a single stage converter; those have been known to harm your batteries. There are a few “smart technology” 4 stage converters like Boondocker or Progressive Dynamics which will be much better at managing and tending your batteries. Also, you migh look into 6V like the Trojan T105’s; much better overall performance then any of the 12V’s, from my experience, short of going Lithium. Good luck!

  2. John Windler says

    I bought from you a few years ago, your Go Power 120 solar charger (which has it own built in controller), which works and has served me well for a number of years on my old Airstream as a stand alone charger. I am now buying a new Airstream, which has 270w of onboard roof panels. Am I understanding correctly, that systems are not compatible and that I cannot plug my Go Power into the Zamp connection and use both? If I can not do this, what is the workaround (like bypassing the Go Power controller) as I do not want to trash my Go Power? Or, can the onboard be turned off (like when in the shade) and the Go Power connected from a sunny location (and maybe connect the Go Power with its direct to battery connections? Or, is the Go Power toast? Is your new solar offering also not compatible as an additional portable offering? THANKS!

    • RichLuhr says

      Good questions.

      1. The Go Power and Zamp controllers are likely to have different charging profiles, and the solar panels are not matched in output, so it is likely that you will get less-than-optimal performance from one controller or the other. In other words, one of them will probably turn off prematurely or reduce its output based on what the other controller is doing. But you CAN still use them both, as long as you recognize that the actual performance will vary depending on a number of conditions (shading on the panels, settings of the controllers, state of battery charge, temperature, etc).

      2. If you wired in a cutoff switch for the rooftop solar (as you suggested), then yes, you could switch between the two systems. To my mind, this is the optimal solution. You would be able to choose the system you wish to use based on the sunlight available.

      3. I’m not sure you were suggesting this, but for anyone reading this I want to be clear: you should NEVER connect solar panels directly to the battery without a controller. Solar panels can output much higher voltage than would be safe for the battery bank, and this can cause a dangerous condition. A charge controller is always required.

      4. We don’t generally recommend any portable solar kit to someone who already has rooftop panels, because we can’t predict the results. We don’t know the output of the rooftop panels or the charging profile of their controller. But it would be overstating things to say our Portable Solar Kit is not compatible. It’s just that we can’t guarantee compatibility with existing rooftop systems that we didn’t sell.

  3. Richard Fulton says

    Another disadvantage of portable solar is the higher risk of getting stolen in the campground if you leave them out when you’re not there. It’s not clear that you can lock them up.
    Thanks for the info on the apparent inability to use both portable and rooftop panels together….did not think about that subtle fact.

  4. RichLuhr says

    Agreed, although I’ve never had anything stolen from a campground in 16 years of Airstreaming, including my portable solar panels. Maybe that’s because most people don’t notice it silently collecting photons!

  5. Mike Beavers says

    Thanks for the information. To expand on the fixed/portable combined issue, I recently had a 400W Zamp rooftop system installed along with lithium batteries in our 2020 Globetrotter and wanted the flexibility to use a portable for those times when the trailer might be in a shady spot. To your point, my installer (AM Solar in Oregon) also suggested either modifying my existing portable unit by removing the controller or purchasing a new unit unit without a controller to avoid the issues that can arise with dual controllers. I went with a Zamp 180W portable and the solar port on the Airstream was rewired so that all panels, portable and fixed, would run through my new Victron controller.

    • RichLuhr says

      That’s an excellent solution worth considering for anyone who is installing a rooftop solar array. Might as well get maximum flexibility with both rooftop and portable!

    • says

      Thanks for that, Mike and Rich. Yes, I recently purchased the new portable solar package from Airstream Life without considering that it might conflict with the factory-installed Victron-controlled 180w solar system on my 2021 Globetrotter. My plan now is to turn off the on-board Victron controller and use the portable unit in the morning, late afternoon, and when the GT is in the shade. Ultimately, though, I’d like to get the rig re-wired so that the Victron just thinks it’s part of the family.

  6. says

    Thank you for this post, it answered a couple questions, We have a Sport22 so there wouldn’t be a ton of roof space for solar.
    My questions are –
    Does solar do a better job at charging the battery when the AS is hooked up to normal house power (15amp)
    and How many batteries would it take to run the AC on this AS? Is that even possible?
    Thanks,
    Alan

    • RichLuhr says

      1. That’s hard to answer because “better” is subjective. Both will charge the batteries fully. But if I had the option of plugging in, I’d plug in.

      2. It would be impractical to carry enough batteries to run the air conditioning in a Sport 22. It’s extremely rare that people even try it, with a travel trailer. You’d need a massive bank of batteries and at least a 3000-watt pure sine inverter, and even then you wouldn’t be able to run the air for very long. If you need air conditioning, you’ll be better off plugging in to shore power or a generator.

  7. Meredith Gee says

    Your ad says it’s ready for standard or AGM batteries. What about the new Lithium ion batteries. Our new International is coming with those. Can I use this panel system the same way? Also, in full sun, how long does it take to recharge the batteries as compared to 4000 watts of generator?
    Thanks

    • RichLuhr says

      We’ll have a version of the Portable Solar Kit that supports lithium batteries in about two weeks. If you want to be notified when it’s available, send an email to store@airstreamlife.com. It will work exactly the same way.

      It’s impossible to precisely answer your question about charge time, because it would depend on the size of your battery bank, the time of year (full sun in winter can be very different from full sun in summer), and how far depleted the batteries were when you started.

      A big generator will not charge the batteries more quickly than a small one, because even the smallest generator puts out far more power than the batteries need to recharge. Solar generally works best for charging batteries fully.

      To better understand charging times, try reading this post: http://howto.airstreamlife.com/2015/11/03/solar-vs-generator/

  8. John Boxell says

    Thanks for this post. We have a 160 watt GO Power panel installed on the roof by Can-Am in 2013 which has worked fine (when in sun). We are considering adding a portable panel by GO Power to augment the existing roof top panel – possibly their 130 watt model. This would be connected via a 7 pin trailer adapter. The batteries (new) are group 24 AGM. Do you consider this a viable option.

    Thanks,
    BTW – if you recall, we met at Organ Pipe NM back in February 2016.

    • RichLuhr says

      Hi John — good question. Whether you connect through the 7-way adapter or the “Zamp only” plug, you have the same issue of competing solar controllers. And you can’t run a 130 watt panel directly into either connection without a solar charge controller. They both go directly to the battery, and dumping power directly from solar panel into the battery would destroy the battery.

      One option would be to pay a bit more and have a plug wired into the existing charge controller so that your portable panel is controlled by it. However, you’d need to verify that the 130 watt Go Power panel has the same output profile as the existing panels. You should consider using the same 160 watt panel for this reason.

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