How We Mounted Solar Panels on a Fiberglass Van Roof


Every van is different, and throughout our van build we’ve found that ours poses some unique challenges with the shape and contours of its roof. Nothing is simple when you’re working with a curved surface, and mounting our solar panels was no different.

Solar power is a must for van life. Electricity gives us the ability to have lights and a fridge, run a fan, charge phones and computers, and work on the road. And solar panels let us be completely off grid, using only the energy that the sun gives to us.

Setting up your solar power system can be as simple or complex as you want it to be. From self-contained units to piecing together every component individually, there’s something out there for every budget and skill level.

Unless you want to prop up your solar panels on the ground every day, you’ll need to mount them to your van roof. And if you have a high top conversion van like ours, this may not be simple.

What We Went With

For our solar setup, we went with the Renogy 400-watt starter kit with the 40A MPPT controller. This kit comes with just about everything you need except for the batteries, and for those we picked up a pair of VMAX 155ah deep cycle batteries.

This large of a system may be overkill for our electricity needs, but hey, it’s better than running out of juice in the middle of the woods. We did a lot of research about sizing everything properly, but only came away more confused than when we started. So we decided to go big and see how it works.

If you’re looking for a smaller system, Renogy offers 100-watt and 200-watt kits, and VMAX also has smaller battery sizes.

All of this stuff arrived at our house in five large, heavy boxes from Amazon. The UPS guy probably hates us by now. Unpacking everything was a lot of fun, but then we had to figure out the best way to mount solar panels on our fiberglass van roof.

How Do We Mount Solar Panels to this Screwy Surface?


Our van roof is weird. It’s a fiberglass high topper, and it has a lot of curves, slopes and grooves. So not only did we have to decide on the best way to attach mounting brackets to relatively flimsy fiberglass, we also had to figure out how to mount flat solar panels on a non-flat surface.

A lot of RVers and vanlifers use 3M VHB tape to mount their solar panels. This stuff is incredibly strong (they use it to install windows in skyscrapers) and it eliminates the need to drill holes in your roof. But there’s something unsettling about the idea of flying down the highway at 70 mph knowing our solar panels are only held on with tape, so we decided to bolt ours down.

The Renogy kit comes with self-tapping screws for mounting to sheet metal, but fiberglass doesn’t provide as much hold so we had to come up with something different. We found this post on that talks about reinforcing the fiberglass roof with strips of plywood and screwing the panels down into the wood. Bingo!

We also picked up some Loctite PL Marine adhesive for some extra security, and Dicor lap sealant for waterproofing.

Now that we had our game plan, we could get to the installation.

Mounting the Solar Panels Step-by-Step

Attach brackets to the solar panels.

The Renogy kit comes with their Z-bracket mounting system, which mounts the solar panels with about an inch of space underneath them for airflow. Each panel needs four brackets, and there are several ways to configure them. We initially attached the brackets to the bolt holes closest to the corners.

Dry fit the solar panels on the van roof.

It’s important to dry fit everything first to see how it looks on your van roof. We tested a couple different layouts before deciding what worked best. We also had to change the bracket configuration a few times to get the panels to sit just right.

Because of the huge curve in the middle of our van’s roof, only one of the panels mounted flat right off the bat. The others had pretty hefty gaps between the mounting brackets and the fiberglass.


To fix this, John cut angled spacers out of scrap wood and painted them to seal them from the elements. These spacers worked perfectly and provided something for the brackets to sit on.


Mark and drill holes in the van roof.


This was the scary part. Once we had the panels how we wanted, we marked the bracket holes with a Sharpie and drilled into the van roof. No turning back now!

Cut plywood reinforcement strips and drill holes.

For the plywood reinforcements, we used strips of ¾” scrap plywood that we gutted from the van. The strips were already about 4 inches wide, and we cut them down to about 6-8 inches in length.


For the first set of these, we used Gorilla tape to hold them up to the roof under the pilot holes, then drilled down into the plywood from the top. This turned out to be a pain, and we eventually figured out that it was much easier to measure the hole spacing and drill into the plywood separately.


We had to cut smaller strips of plywood for spacers when the solar panels were above a ridge in the ceiling.

Clean roof and apply Loctite PL adhesive.

With any adhesive, the surface needs to be clean to get the best grip. We wiped down the van roof underneath the mounting brackets with rubbing alcohol. Man, was our van roof dirty! In hindsight, we should have given the whole van a thorough scrub before mounting things to the roof.


The next step was to spread Loctite PL Marine Adhesive underneath the brackets. This stuff is used for permanently joining various materials together on boats (including wood, fiberglass, and metal), and it provides a flexible, strong, and watertight bond.

For the solar panels with wooden spacers, we applied PL adhesive to each side of the spacers so it would adhere to the bracket and the van roof.

Bolt solar panels to roof and plywood strips.

We used bolts, nuts and washers to hold down our solar panels. The plywood spreads out the tension from the solar panels and gives them something meatier than the thin fiberglass to hold on to. The holes on the Renogy Z-brackets will fit ¼” bolts.


We used a washer under the bolt head at the top, and a wide washer under the nut on the inside of the van for more of a contact point with the plywood strips.

Let adhesive cure, then seal with Dicor lap sealant.

We let the adhesive cure for 24 hours, then we used a caulk gun to douse the brackets in Dicor lap sealant. This seals everything up so all the holes we drilled into the roof won’t leak.

We covered every seam and bolt head in Dicor, and we also made sure to completely cover the wooden spacers to further protect them from the elements.

Cut off excess bolts inside van.

The bolts we used extended a few inches past the plywood on the inside. We needed to cut off the excess so they wouldn’t interfere with putting up the ceiling.


We used a friend’s angle grinder to shear off the extra length, but you could also use bolt cutters or a hacksaw.

Wire panels together and run wiring inside van.

The Renogy kit comes set to wire the panels in series, but we wanted to wire ours in parallel. We used these Signstek Y Branch MC4 Cable Connectors to wire the panels together.

To run the wires inside the van, we had to drill a ¾” hole in the side of the topper. To ensure this hole is fully leakproof, we picked up this Weatherproof Double Wire Entry Gland from LINKSOLAR and attached it using 3M VHB tape and plenty of Dicor sealant.

We’ll cover wiring the electrical system, including solar, in detail in a future post.

We Have Solar Panels!


Our fiberglass van topper didn’t make this easy, but we now have three solar panels mounted to the roof! We’re going to keep the fourth one in the underbed storage and set it up using a tilt mount when we’re boondocking for longer periods.

Next up is installing a vent fan, wiring and flooring. It’s amazing to see how everything is coming together, and we can’t wait to share the finished Gnomad Home with you all. Thanks again for all the love and support and don’t forget to follow us on Instagram: @gnomad_home and on Facebook at: Gnomad Home.

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  1. Tim on December 19, 2016 at 10:10 pm

    Somewhere I saw it mentioned that you are in Affton , is that the st. Louis Affton as I also live in Affton and I would love to see this project I just came across it. I am down by Syberg’s 7 houses up on the west side Street.

    • John John on January 1, 2017 at 10:36 pm

      Hey there Tim! We apologize for the delayed response! We would love to show you the van! Send us an e-mail at and we can set up a time for you to check it out! Thanks for following!

  2. Rob on May 6, 2017 at 2:35 pm

    Thanks for this post. Have you found that your batteries provide adequate power supply?

    What is the max depth of discharge you allow your batteries to run to before recharging?

    How long do you find it takes to go from that max depth to full equalized/float charge level?

    Thanks again!

    • John John on May 6, 2017 at 5:03 pm

      Hi Rob,

      Thanks for reading! Those are tough questions for me to answer specifically right now since we don’t have a way to accurately measure our batteries’ state of charge. We have the MT-5 Tracer Meter that Renogy recommends for use with their Tracer charge controllers, but we have come to realize that it’s woefully inaccurate. It displays SOC%, but the second the sun goes down and you have a load connected (i.e. lights turned on) it loses 20-30% on the meter immediately, and there’s no way that’s correct. Other people have reported the SOC% dropping dramatically when the sun goes down and increasing dramatically when the sun comes up, so it seems to be an issue with how these meters calculate SOC%.

      Instead of looking at SOC%, I’ve started paying attention to the battery voltage on the meter, which seems to make more sense. When the sun is down (i.e. batteries are not charging) and we have not been using electricity, the voltage sits at 12.9V. Based on what I’ve read on the internet, 12.9V is about 100% charged for AGM batteries. We’ve never run it down below 12.7V, but if we did we would try to keep it above 12.2V, which I think is about 50% charged. When we wake up in the morning (and the batteries are charging from the solar panels) it stays at 13.4V. I’m not sure how long it takes to get back to 100% due to the limitations of the MT-5 meter.

      We plan to get a more accurate meter that we can connect directly to the batteries with a shunt, but those run into the $150-$200 range. We haven’t had any issues yet, so we’re holding off for now. We typically use our batteries to power 12V LED lights (maybe 3 hours per day), our Fan-Tastic fan, ARB fridge, and to charge phones. We keep a fan on low overnight, and we run our inverter for a few hours every day to charge computers. Everything seems to be going well so far, but until we get a better meter we don’t know how far we’re running our batteries down with any real accuracy.

      Let us know if you have any more questions!

      Take care,

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