400 Watt Solar Power System for DIY Van Build

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I’m here for ya.

Seriously! Reach out on Instagram or YouTube with questions.

The video is fun if you get bored of the reading.

 

Step 1:

Decide where you want your solar panels as well as where you want your battery system.

I chose to mount my panels on the back of my rack due to my fan location and the size of my solar array. I also already knew that my battery system was going to sit right behind the driver’s seat. This helped me decide where my solar wires would enter the roof and how long of extension cables I needed to reach my battery bank. (I made the mistake of getting 10ft cables at first, which did not reach my system—see right—so, I ordered 20ft cables and the reached perfectly!)

 
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Step 2:

Mount your panels to the rack and connect the MC4 connectors.

Take this step with a grain of salt. I mounted my panels to my 80/20 cross bars on my rack using the 80/20 fasteners. However, this was super tedious to do (maybe also because I was alone..) and felt insecure at first so I had to jerry-rig the system a little bit. I’ve since driven about 10k miles without any budging of the panels though so perhaps I shouldn’t second guess my jerry-rigging skills.

I started by sliding my panels up onto the roof, positioning them where I wanted them to end up, and connecting the wires from each panel to my MC4 connectors (both red wires from each panel will connect to one MC4 connector and both blacks will do the same to the other MC4 connector). This is called connecting your panels in parallel. (article explaining the difference between series and parallel). This makes the total wattage of my panels cumulative (aka, two 200 watt panels = 400 watts of solar power).

 
 
 
 
 
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NOTE on attaching panels to cross bars:

As for attaching the panels to the 80/20 bars, I used the fasteners along with a bunch of washers to make up for the difference in depth in my 80/20 bars and the length of my fastener screws. I used 8-fasteners per panel (4 on each side), connected all of the fasteners through the pre-existing holes on the back of the solar panel and then slide each panel and it’s 8-80/20 fasteners down the grooves of the 80/20 bars. This was very tedious. Not only was getting each fasteners JUST tight enough to slide down the groove while not being TOO loose totally not fun…but getting the whole thing (2 solar panels and 4 crossbars) up on the roof by myself was no joke…

Even with all that effort, there was still 1/16 of an inch of space with the fasteners, the solar panels and the crossbars so I took some Silicone and plopped a big ole’ bit of goo over each screw head so that it could not vibrate itself loose. I was terrified to drive down the road at highway speeds for the first time but…10k miles has seen zero budge on my panels so I am happy.

Again, if you can come up with a better way to securely mount the panels….please do. This was just what my mind came up with alone at 9pm on a Tuesday in a driveway.

 
 
 

Step 3:

Mount your roof entry gland.

Once your panels are up, your MC4 connectors are connected and you have an idea of where you want your solar wiring to enter the roof, it’s time to either drill your own holes or use a pre-existing factory hole to mount your entry gland and run your solar wiring into the van!

I didn’t like the idea of drilling my own holes knowing that there are factory holes already in the roof, so I decided to open up the rear driver side factory hole and use it to run my solar wiring.

There are a lot of factory holes in the roof (pretty much every other little cap on the roof if you’ve already mounted your rack using the factory mounting locations). I found and verified the hole I ended up using by standing on the back of my van and poking a screwdriver through a little cap from the inside to make sure I was using the correct one (one hole in the back is accessible from the inside, the one I used, the other appears to be harder to access).

Once I had a my hole, I connected my solar extension cables to the corresponding positive and negative connection points on my MC4 connectors, fed those extension cables through the holes on my port, slipped those wires through the now-open hole (the screwdriver one) and fit my entry gland right where I wanted it to make sure it fit alright. It is a little tight with the FVC rack in place but if you press the entry gland so it is flush against the rack, there is plenty of room for your wires to run through the roof.

I then ran two layers of Butyl tape around the bottom edge of the entry gland, fit it on the roof where I’d want it, drilled self-taping sheet metal screws straight through the plastic edge of the entry gland, through the Butyl tape and into the roof to secure the entry gland.

Once the entry gland is screwed down securely but not excessively (the Butyl tape should squeeze out around the edges a bit due to the pressured fit - that is a good thing), I tightened up my wiring by pulling in all the excess and zip-tying the cables left on the roof to one of the nearby crossbars so it would not blow around on the roof and covered the edges and screw locations on the vent with Through the Roof sealant.

Once I was happy with everything and didn’t want to move the wires any more, I also sealed the little nipples of the entry gland around the wires just to be safe.

 
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Step 4:

Connect your solar extension wires to your charge controller!

I waited to do this step until my electrical system was fully operational. Once I was ready to start receiving power from the panels, through the charge controller and to the battery bank, I simply took the positive and negative solar extension cables and connected them to the respective holes in the back of the charge controller.

(the blue box in the bottom left of the photo is my charge controller and the black and red cables leading to it are my solar extension cables running all the way from the panels!)

I read somewhere that you shouldn’t have your solar panels connected to your charge controller until that charge controller is properly setup to feed the battery bank…I may be making that up but it seemed logical to me so I waited!

Final thoughts:

If I were to go back, I’d 100% have someone help me mount the solar panels as that was incredibly difficult to do alone…I’d also spend more time trying to find a more proper way to attach the panels to the 80/20 crossbars.

Also, I accidentally spilled a tiny bit of Silicone on one of the panels (see the discoloration on the right-most panel to the right?) and thought I wiped it off when it happened but it turns out I actually just spread it around. I believe this is impacting my solar capacity as I have only been able to pull in 280 watts max at any given point (with 400 watts of panels). I will clean this off soon and see if it changes how much I can pull in.

 
 
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