Solar – simplified! A guide to the basics

So many people make RV solar power more complicated than it needs to be.

From Amps and Volts to complex math, there's a lot of confusing information out there. If you're a newbie – or even if you're not – it's easy end up down a rabbit hole of numbers yet still not understand the basics of why solar power is such a great power option for Airstream and other RV owners.

Let's clarify something up front: Understanding solar power is EASY. Don't let anyone tell you differently.

If you like geeking out on numbers, that's fine (I'm actually one of those people, too). But you don't NEED that information to benefit from the simplicity of using a solar system to extend your trip and camp longer.

In a nutshell, here's how RV solar power works:

• The sun shines into solar panels
• Solar panels convert the sunshine into electricity
• That electricity charges the batteries
• The batteries run the electrical system 

That's it.

The rest is stuff that only a few people really need to know. Because most people simply want to get more camping time without having to plug in or carry a generator.

So let's simplify the topic of solar power by answering 7 of the most commonly asked questions.

If you prefer a video version of this blog, we collaborated with our friend Brad Driver from Thirteen Adventures to create this one, which has a bit of additional information, too:

1. "What can I run on solar?"

The short answer is: nothing.

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 directly from 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 RV's batteries.

Basically, if it runs on 12 volts (or using the inverter), the batteries are powering it.

If you want details about the exact appliances and systems that the batteries are powering, I included charts in the book, "The Newbies Guide to Airstreaming" (Page 20 in the 4th edition.) 

2. "Can I use the inverter?"

Absolutely.

But keep in mind that the inverter really has nothing to do with solar. The inverter is a device that 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 while you are boondocking away from shore power. At least, until your battery is depleted. Examples of these things are:

• TV
• DVD player
• Laptop
• Phone and other devices

Be mindful that any device that plugs in generally consumes 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.)

3. "What size of solar panel system should I get? How many watts do I need?"

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. But 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. Whether it's more solar on the roof, or a portable solar system, we recommend aiming for about 200 watts, for most people.

Portable systems deliver a lot of benefits at a much lower cost than rooftop systems. And if you don't have room on the roof to add panels, they are a great way to go.

Our AIR GEAR Portable Solar Kit, for example, is simple and powerful. We also designed it to be the lightest weight, highest quality, and best priced in its class. You just unfold it, point it at the sun, plug it in, and walk away.

4. "Should I get a solar system or a generator?"

That really 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 the sun
2. Blissfully quiet
3. Extends your off-grid camping time
4. No heavy generator or messy gasoline cans to carry

If you want more detail on the solar vs. generator topic, check out this blog.

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

You certainly can, and you can choose to expand it with either a rooftop or solar system.

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

If this is a decision you're contemplating, here are a few resources that provide some detail:

• 5 reasons why portable solar might be right for you 
• Why everyone should consider portable solar (even if you already have solar) 

6. "How do I know how much power I have when I'm using solar?"

Sometimes people want to know how much power their panels are generating, or exactly how full their batteries are. 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 and you don't have lithium batteries, you can get by just fine with the built-in battery volt meter that came with your Airstream. It isn't terribly accurate but it's close enough for casual use.

(Important: If you have lithium batteries, the built-in battery volt meter is not accurate at all. In this case you need an amp-hour meter.)

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.)

7. "Do I need to upgrade my batteries?"

I realize this question is not specifically about solar. But many people ask about batteries when they are asking me about solar. And since solar power charges the batteries, the two are certainly linked.

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

• They're worn out and not taking a full charge anymore.
• You want to install a solar panel system larger than about 200 watts. In this case, you will find that 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 talk to the RV solar specialist who is doing the work. They can help you match the battery bank to the capacity of your panels.
• You would like to switch to lithium batteries, for added capacity. If you're looking for more detail about this, check out our guide, Diary of a Lithium Battery Upgrade, in which I document my research and experience upgrading our rig to lithium batteries.

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