Who needs 400 watts of solar panels?

When adding solar panels to a travel trailer or motorhome, many people adopt the philosophy "add as much as you possibly can."

There a couple of reasons for this.

One reason is that having more solar capacity than you really need will give you an edge on days when conditions are marginal. For example, perhaps you camp in areas where it's common to be cloudy for days at a time. Your solar panels might produce as little as 10-20% of their rated capacity on a cloudy day.

You can encounter the same problem if you camp in the winter, when the sun is low and solar production plummets.

Or perhaps you are just a gear junkie and you really need a lot of power for your electronics (TV, computers, Starlink, CPAP, electric fridge, etc).

Whatever the reason, until recently there have been two major limitations to adding heaps of solar panels to any RV:

1. Adding rooftop solar panels can get very expensive, especially when you add in labor costs. Typically you'll spend a few thousand dollars to get a sizable solar array installed.
2. There's only so much space available on the roof, so you're limited to the number of panels that will fit up there.

Portable Solar Panels are a Great Solution

Portable solar panels are much less expensive and they can be angled to face the sun (which means they perform better). But the typical factory-installed solar plug, wiring, and fuse aren't designed to connect really large portable solar arrays. That's why we recommend a maximum of 200 watts through the factory-installed solar plug. That's enough power for many people, in average situations.

Recently we started thinking: What if we could connect two of our Portable Solar Kits, for a total of 400 watts, to the Airstream? [Cue caveman grunting sounds] Two such kits, we reasoned, would cost a fraction of the equivalent rooftop panels, and they would perform better too.

Last month, we began testing this idea, and we've been amazed at the results.

The trick to getting 400 watts with our AIR GEAR Portable Solar Kit is to connect the first set of panels through the solar plug, and another AIR GEAR Portable Solar Kit through the 7-way cable (the cable that connects to the tow vehicle when you're towing). Each of these connection points is connected to the battery, and each can handle a 200 watt solar panel. 

This solution works for most* Airstream trailers made from 2017 onward, with a factory-installed Solar Port on the A-frame near the spare tire handle.

* Two important notes: First, this doesn't work on 2024 and later Trade Wind trailers, due to a battery isolator installed on those models. Second, on other 2024 and later Airstream trailers there may be a 10-amp fuse for the solar plug, which will need to be upgraded to a 20-amp fuse. Regardless, the wiring can handle the output of this solar kit.

Our Airstream getting 400 watts of solar power at a recent rally

And wow, does it work

The above photo is our Airstream at the recent Cali Rally we attended. In the photo you can see how the Airstream was almost completely shaded by trees. If we'd been relying on rooftop panels we would have gotten very little power during the day.

Thanks to the portable panels, we could move them out of the shady area, and angle them to face the sun for maximum power gain. Even with the sun low on the horizon in the morning, our batteries were charging more quickly than I've ever seen before.

At this boondocking rally we generated so much power that our batteries were 100% full by noon. All around us, people were running out of battery power (even people with generators, due to limited generator hours) but we had so much extra we couldn't use it all.

On the final day of the rally we ended up lending a panel to a couple whose rooftop solar couldn't hack it—and still we left the rally with 100% in our batteries, after 4 days.

So the answer to the question, "Who needs 400 watts of solar panels?" is apparently, "we do!" 

We won't pull out both of the AIR GEAR Portable Solar Kits every time we're boondocking, but we're now confident that when the going gets rough or the clouds roll in, we've got capacity to spare.