Solar – simplified! A guide to the basics

Recently, we attended an educational seminar on the topic of solar power for Airstreams. The presenter turned what is a simple topic into an engineering class that would intimidate all but the geekiest among us. His first series of slides were densely-packed with numbers and technical terms and unfortunately, he confused a lot of attendees.

So let's clarify something right up front: Solar is easy. Don't let anyone tell you differently.

In a nutshell, here's how it works:

• The sun shines
• Solar panels convert the sunshine into electricity
• That electricity charges the batteries in your Airstream
• Your batteries run the electrical system in your Airstream

That's it.

The rest is stuff that only a few people really need to know. If you enjoy having all the details and talking about amps and volts (like me, I have to admit) by all means have fun learning everything you can. But I think most Airstreamers just want to get more camping time without having to find a plug or carry a generator.

So let me simplify the topic of solar power by answering the most commonly asked questions:

"What can I run on solar?"

I often hear comments and questions from people who don't understand exactly what solar panels are doing for them. At the risk of repeating myself: the solar panels charge the batteries. Solar panels don't do anything else. You don't "run" anything on solar. 

The batteries in your Airstream are what "run" things. Which is why, when you're boondocking (not plugged into shore power), you want to keep your batteries charged. That's so you can use all the things that run off your Airstream's batteries.

In my book "The Newbies Guide to Airstreaming" I have charts that show exactly what the batteries are powering. (In the 4th edition of the book you'll find that chart on page 20.) Basically, if it runs on 12 volts, the batteries are powering it.

"Can I use the inverter?"

Sure. The inverter really has nothing to do with solar. It uses the battery's energy to power the electrical outlets in the trailer. In other words, the inverter makes it possible for you to use things that have plugs, like the TV, DVD player and your laptop, when you're boondocking—at least until the batteries run down.

Keep in mind that the devices that plug in generally consume a lot of energy, so you should use them sparingly when you're using the inverter. (I've done a more detailed blog on inverters which you can read here.)

"What size of solar panel system should I get?"

Unless you're planning to camp off-grid for long periods of time, you don't need a particularly large solar array. 

Solar panels are usually rated in terms of watts. The watt rating is really only useful for comparing one system to another since the actual energy generated on a given day varies depending on factors like cloudiness, time of year, and latitude.

With the ever-increasing electrical needs of Airstreams these days, don't bother with a system of less than 120 watts. About 160 to 200 watts is plenty for most people.

You can get a lot of benefits from a simple portable solar setup like this one. You just unfold it, point it at the sun, plug it in, and walk away.

"Should I get solar or a generator?"

That depends on how you camp or travel. If you need to run things that consume a lot of power (like an air conditioner, microwave oven, hairdryer, CPAP machine, etc.) when you're away from hookups, a generator will probably be the best choice.

But if you just want more battery power, solar has big advantages:

1. Free energy from Mr. Sun
2. Blissful silence
3. Extended off-grid camping time
4. No heavy generator or gasoline cans to carry

If you want more detail on this topic, check out this blog.

"What if I want to expand my solar capacity later?"

You should look at the benefits of portable solar panels. I wrote a separate blog about this topic that explains why they make sense for everyone.

Expanding capacity with portable solar is much less expensive than expanding a rooftop installation – which can cost thousands in equipment and labor.

"How do I know how much power I have?"

Sometimes people want to know how much power their panels are generating, or exactly how full their batteries are. This is entirely optional, but in this case, I recommend installing an amp-hour meter such as those made by Victron (SmartShunt or BM-7xx series), Xantrex (Link series), Bogart Engineering (Tri-Metric), etc. These are much more useful than having a monitor on the solar panels themselves.

If you are less concerned with exact numbers, you can get by just fine with the built-in battery meter that came with your Airstream. It isn't terribly accurate but it's close enough for casual use.

To be honest I don't even look at the numbers anymore. I just plug my solar panels in for the day and as long as we get a few hours of sunshine I know we're fine for another day at least. (I could explain the math behind this, but I'm trying not to go down the rabbit hole of numbers here.)

"Do I need to upgrade my batteries?"

I realize this question is not specifically about solar. But many people ask it when they are asking me about solar.

For most people, the answer is: no. But there are three primary cases where you should replace the batteries in your Airstream:

1. They're worn out and not taking a full charge anymore.
2. You're going to install a solar panel system larger than about 200 watts. In this case, you'd find there are a lot of days when the solar panels are producing more power than you can store, which means you'd have a lot of solar capacity that you can't use. If you're installing more than 200 watts you're probably paying a fair amount to install rooftop panels, so you should talk to the RV solar specialist that is doing the work. They can help you match the battery bank to the capacity of your panels.
3. You would like to switch to lithium batteries, for added capacity. Learn more about lithium batteries here.

Bottom line: Solar is easy. Take in the free energy that the sun gives you and go enjoy your day.

If you want to check out my pick for a really simple and lightweight solar panel system, look here.