The day before I left for my recent road trip I decided to install a second solar panel on the roof of my van. Because what better idea than to start a major project 24 hours before you spend a week driving 2,000 miles.

I did a bunch of math before purchasing my first solar panel. I assumed the solar panel — a 200w flexible solar panel from AllPowers — would, you know, collect 200 watts of power from the sun all day, every day. If you already have a solar panel you may already be chuckling to yourself. The most I’ve ever got from my 200w solar panel is about 135 watts and usually I get less than that. For maximum performance from a solar panel it should be cool and pointed at the exact correct angle. As you might imagine, taping a flexible one tot he hot roof of a van is a less than ideal installation method.

I installed my first solar panel last year and mounted it with a combination of 3M VHB tape on the bottom and Flex Tape all around the edges. I discovered the technique from another YouTuber who installed a similar solar panel on his van five years ago using this method and it’s still attached. I used some cleaner/degreaser to clean everywhere adhesive would touch. I’m not saying this is the world’s most permanent installation method, but so far it has worked for me just fine.

There are two ways to wire two solar panels together: parallel and series. People have literally written books about solar power and frankly I didn’t have the time, nor was I interested in reading one. Connecting two panels in parallel is basically like having two independent panels, each one charging your battery independently but at the same time. When you do this you need to add the incoming amps from each panel together and make sure the battery you’re charging can handle it. You may also need to add some fuses and, in some cases, make sure your wiring can handle the additional amps. When you wire two panels in series, you are essentially turning them into one big panel. In this configuration you add the incoming volts (not the amps) and will again need to make sure your battery can handle it. The downside to this configuration is that if one panel breaks, the whole thing is broken. If one panel is in the shade, nothing will charge. The upside is that wiring panels in series is super, super simple. I decided to wire mine in series, mostly because it was the easiest and fastest solution.

For all the dirty details, you can watch the YouTube video at the top of this post. The short version is that I found a spot to put the panel, added all the tape, and put it in place.

The last thing I did was use a garden hose and clean off the roof of the van. Don’t do that. I ended up getting water under the edge of the tape and about 100 miles into my trip, the tape started coming loose. Drying off the roof and pressing the tape down fixed that, but hearing the sound of flapping from your roof while doing 70 miles per hour on the interstate will make your butt pucker. It did mine.

Because the highest number I’ve ever seen from my solar panel was 130 watts, I was expecting to get 260 watts after adding the second panel. The results I got on the road were quite surprising. The highest number I saw while driving was 380 watts, and I routinely saw numbers in the high-200s and low-300s. I was incredibly shocked to see those numbers. I think it takes a perfect combination of sun, weather, and wind to cool the panels.

That being said, everything I was getting before has been doubled. On days when I used to get 50 watts, now I get 100. Under conditions when I used to get 100 watts, now I get 200.

More than numbers, I now get enough solar — again, on a good day — to keep my battery topped up. On my recent trip I was able to spend multiple days off-grid while running an refrigerator and my CPAP and keeping everything powered by the sun. What more could a person ask for?