100 watt solar panel on my truck roof, charging an independent gel battery in my truck bed for camping.
Step 1: Prep the Roof
I used the foam from the solar panel packaging to figure out placement on the roof. I've offset my panel to the side, so that when my SUP is on my roof racks the whole panel isn't covered.
Clean up the fiberglass with acetone (or similar solvent) specifically where the panel feet are going to contact the roof. Use a sharpie to mark where the corners will go.
Obviously stay safe. The fiberglass roof is not designed to take the weight of a grown adult, so no climbing on the roof. I'm using scaffolding and my tailgate and truck bed step to safely work on the roof.
Step 2: Prep Panel
The solar panel is a 100 watt panel from Renology, which comes as part of this kit.
I've used 3M VHB 4910 tape I bought off amazon. You can look up the specs online, suffice it to say it's super strong, good from -40 to +200. I went with tape because NO WAY am I drilling 8 holes in the roof of my 1/4" fibreglass canopy. I've had the panel on for a couple months now, and although I haven't tried driving through a hurricane, it has been fine at highway speeds.
Bolt on the feet as instructed in the kit. Cover all of the foot that will contact the roof with 3M tape.
Connect the cables to the solar panel. They look identical so you need to mark which one is hot and which one is ground on part of the cables that is not under the panel, because once you stick it on the roof you won't be able to check. Use a white marker or some string to wrap around the cable.
Step 3: Stick Panel to Roof
The 3M tape is supposed to be applied at around 15 degrees Celsius. I'm up in Canada, and no one I know has a garage that fits a 20' truck, so I improvised. I've got a space heater in the back of the truck facing up that I've been running for an hour to heat up the fiberglass.
After placing the panel on the roof (with the tape backing STILL ON each foot) lift one foot corner at a time.
Think ahead: Start with the foot it is hardest for you to reach, and leave the easiest one for last.
Heat up the foot with a hairdryer (it's aluminum it heats up quickly, don't burn yourself) and carefully remove the tape backing. You might try using a small flat head screwdriver or utility knife point to carefully peel off the tape backing. Place the foot down on the roof. You only get ONE CHANCE at this, so don't mess it up. Push down on the foot for a minute or so.
Repeat with each foot. The last one is going to be the hardest to do, as all three other corners are already stuck down.
Step 4: Optional: Safety Line
Just in case the tape were to fail, I added two safety lines running forward from the front corners of the panel and attaching to my roof-rack support. The idea being if the tape fails the panel won't go flipping off my roof and hurting someone driving behind me. I drilled a small hole in the roof-rack support (try not to let the drill bit scratch your gel-coat when it suddenly punches through!) . I used 3M Excel Marlow 4mm rope (designed for sailboat racing) it has a breaking strength of ~1500 lbs and is super low stretch.
Step 5: 12V Marine Through-Put
I've used a 12V Marine Watertight Deck Connector to get the wiring for the panel to the inside of the truck bed in a way that won't lead to ceiling leaks. https://www.amazon.ca/Perko-1190DP0CHR-Marine-Wate...
The one I bought is 15 Amps. The panel is technically 30, but I'm not going to be drawing that much so this should be fine. If I were doing it again I'd look for a higher amp fitting.
Make sure to buy a fitting that fits the cable size. This solar panel kit comes with 10 gauge wiring. It was very tricky to wire up the deck fitting as this is the maximum gauge it fits.
Mark where you are going to place the fitting. Drill it out with a spade or hole bit of the appropriate size. Dry fit the deck fitting to make sure it fits snugly.
Figure out where to cut your panel wires so they will come out from under the panel and connect to the deck fitting without exra wire to flap around in the wind but also not so short that you create tension on the fitting.
Connect your wiring to both the male and female sides of the fitting. Make sure to mark which wire is hot and ground on the wires that will be inside the canopy.
I've used white Fast-Cure 5200 http://www.amazon.com/3M-Marine-Adhesive-Sealant-5... to attach the fitting to the canopy, instead of screws. Again, I don't like drilling holes in things that are meant to keep the rain out. This stuff both sticks and makes things watertight. Once it sets up you won't be able to remove the fitting without tearing out the fiberglass, so again don't mess this up. Marine adhesive is super messy and can only be cleaned up using acetone or a similar solvent. It will not come off of your clothes ever, or your skin for many days. Wear gloves and work clothes, clean up your work area and have a rag and acetone handy. Be careful and only put it where you want it!
Apply sealant to bottom of fitting. Insert into hole in canopy. Apply pressure downwards gently to squeeze out any excess sealant and ensure it fills in any gaps. Put something heavy on top while it cures. Clean up any excess carefully. Check inside the canopy for any drips or dangling sealant and clean that up before it sets up as well.
**UPDATE** The original throughput I used corroded horribly over the winter, so I've replaced it with a different type which doesn't require you to cut the wires and forms a nice waterproof seal.
Step 6: Connect to Your Battery
Inside the canopy, run your wiring down to wherever your battery is being kept. Make sure to follow the solar panel instructions with regards to charge controller, battery and fuse. Make sure your battery is safely placed where it will not bounce around, get dirty or damaged, and has enough airflow to deal with heat buildup.
I have a 35 Amp Hour Gel Battery in a waterproof plastic toolbox. It is mounted in the side compartment of my sleeping platform. Currently it is connected to/running my canopy light and two USB's and a 12V power socket on it's own switch.. I will probably add more lighting in the canopy etc in the future. Now when I'm camping in the backcountry I can re-charge my phone, GPS, run a small fan, bluetooth speaker etc. and not have to worry about running down my starter battery.