Sprinter Van Solar Panel Installation: Easy and Affordable

Van Solar Panel Installation

Trying to find the best solar panels for a van conversion can seem overwhelming.  There are so many options and deciding what is best for you might feel like a challenge in the beginning.  After doing much research, we share our solution for an affordable Sprinter van solar panel installation.  It's an easy-to-install, turn-key solar package that’s easily adaptable to various Sprinter models and build requirements.

This is the final installment in a three-part series that covers everything we’re installing on our Sprinter’s roof; the other two videos cover OEM Roof Rails and Maxxfan installations.

If you'd prefer to watch our solar install video, we've included a link below.  Otherwise, continue reading to learn more!

 

Disclosure: This page may contain affiliate links. Clicking through for additional information or to make a purchase may result in a small commission at no extra cost to you. We hope you find this information useful and welcome any questions you may have.

Van Solar Panel Project Goals

It’s easy to get lost in a seemingly endless sea of solar panel decisions when researching the best van solar setup:

• • • Monocrystalline or Polycrystalline?
    • Rigid panels or flexible?
    • How many watts?
    • What size panels?
    • MPPT or PWM?
    • Series or Parallel?

After a bit of research, our approach was to simplify the decision to 3 basic questions:

• • 1. How do we want to use our roof real estate?
    2. How much solar power do we need?
    3. What are the best solar panels for a van conversion that meets our needs?

We'll begin with the first question: How do we want to use our roof real estate?

There are lots of things that can go on the roof, for example:

• • • Installing a full roof rack
    • adding extra storage
    • A/C
    • Fans
    • Lights
    • Solar
    • Awning

But, loading up the roof comes with drawbacks.  Namely, added weight (i.e. higher center of gravity) and wind resistance, which both negatively impact handling and fuel economy.

That said, we decided to limit our roof space to 2 high priorities:  Ventilation & solar power.

Since we installed two Maxxfan’s, that left approximately 188” long x 52” wide for solar panels.

For the next question: How much van solar power do we need?

The simple answer is -- as much as we can fit. To clarify, here’s some background:  we’re building our van to support primarily off-the-grid travel.  That said, our electrical system will have 3 charging inputs to fuel a lithium battery bank:

• • • Solar
    • Alternator
    • Shore power

For off-grid travel, van solar power is particularly important as more solar equals less reliance on driving and campsite hookups to meet our power needs.

But the question is: how much solar power do we need to fund our needs?

Based on our estimated average daily power consumption and expected travel plans, we initially estimated a minimum of 300 AH’s of lithium and 450 watts of solar.  Rather than building our solar to meet this estimate, we set our estimate as a baseline and opted to add as many solar panels as possible.  Our logic -- as long as our solar exceeds our baseline, we should be OK. And, more is better, i.e. less worry about cloudy days, chasing snow, adding another appliance, etc.

And, for the last question…Which van solar panels are best?

It’s easy to get lost in tech specs when selecting solar panels.  To narrow our search, we focused on reasonably priced, rigid monocrystalline panels.  This combination offers plenty of good options.

To further simplify our search, we focused on achieving 2 basic goals:

1. 1. We wanted quality panels that strike the right balance between efficiency, reliability and cost (i.e. reasonably priced panels built by reputable manufacturers with a minimum efficiency rating of 19%. As reference, most panels we looked at range between 17 and 22 percent. Higher efficiency = more solar converted to electricity)
   2. This is the tricky bit, we wanted to find the ‘right size’ panels. By right size, we mean panels that:

• • • Fit as many watts on the roof as possible
    • Make installation as quick, easy, and turn-key, as possible
    • Translation: Size matters. The right size panels can maximize van solar power output and avoid installation hassles by eliminating the need to create a custom mounting frame.

Our Van Solar Panel Solution – a Turn-Key Van Solar Kit

We’ll admit, finding panels that ticked all the boxes took a good bit of research.  After hours spent pouring through various options, we decided on 525 watts of solar produced by 3 x Renogy 175 watt monocrystalline panels mounted to OEM roof rails using Direct Mount Towers. These three items combined make the ideal van solar kit.

The Renogy panels strike a solid balance between cost and performance with a competitive price tag and a respectable efficiency rating of 19.8%.  But, what makes the Renogy panels even more attractive are the dimensions, which closely align with a Sprinter’s roof width and OEM roof rail placement.

We were sold. This made installation about as plug and play as it gets.

There was no need to spend time fabricating a custom rack or mounting system to bridge the gap between the panels and roof rails.  We just simply used a set of Direct Mount Towers to bolt the panels directly to the OEM roof rails.

And, a very important consideration for us, Renogy’s 175-watt panels are sized to make the most of available roof space by covering the entire roof without any unsightly overhang. Mounted between the Maxxfan’s on our Sprinter 170, the solar panels fit with enough free space between the panels and fans to reduce the risk of fan shadows hitting the panels.

 

Installing Solar Panels on a Van: Getting Organized

Installing the Renogy 175-watt panels is a simple process, which basically requires two steps:

1. 1. Mount the panels to the van roof
   2. Wire the panels together and run the wires through the roof to a charge controller inside the van

If, like our Sprinter, yours didn’t come with factory installed roof rails, we put together a guide to OEM roof rails installation.

Step 1: Drill Mounting Holes

To mount our solar panels, we used Direct Mount Towers which bolt into our roof rails.  The towers come in sets of two & include all the SS mounting hardware required to mount the towers to the panels and OEM roof rails.  Mounting requires 4 towers per panel, which means we’ll need a total of 8 towers (4 towers for 1 panel + 2 add’l towers for each additional panel).

To install the towers, we first drilled holes in the bottom of the solar panel frame, which we used to bolt the towers to the solar panels.

As a side note, Impact Products, the company that manfactures the towers, notes on their website that drilling holes in Renogy panels doesn’t void the warranty. We didn’t verify this. But, if you’re concerned about voiding the warranty, we’d encourage you to confirm with Renogy before drilling.

It’s important to drill the holes in the right place, so that the solar panels, towers, and roof rails line up during installation. This step takes a bit of measuring to work out exactly where to drill the holes.

We found that the easiest way to line-up the holes is to create a template, which you can use to mark the hole locations for each tower. We started by creating a paper template but found it easier to mark our holes by tracing our paper template onto a cardboard cutout. (We demonstrate this template in the video, linked above.)

To mark our holes, we placed our panels face down on a workbench in the order they’ll be installed on the roof. To keep everything straight, we noted the order on the back of each panel for reference during install.

We made sure to position our panels so that the panel wiring was located on the same side of the van as our electrical system. The idea here is to minimize the total length of wires required to connect the panels to our charge controller inside the van, reducing wiring costs and power loss.

If you’re like us, you may be tempted to try and use the existing holes in the solar panels rather than drilling new ones.  We tried and thought we had it worked out, but a quick test fit proved we were close, but not close enough for a proper fit.

With our panels laid out, we used our template to mark our holes with a Sharpie for each tower.  With our holes marked, we were ready to drill.

It’s important to take extra care when drilling holes in the solar panel’s frame as you don’t want to do anything that could damage the actual solar panel.  To avoid accidentally drilling too far and damaging the back of the solar panel, we placed a piece of ½” plywood under the area where we were drilling to protect the panel.  Another option is to fit the drill with a stop collar to prevent the drill bit from going too deep and hitting the panel.

Bottom line: proceed with caution.

Step 2: Paint the Solar Panel Frame (Optional)

This step is completely optional, but if you’re interested, read more to learn how to paint a solar panel frame. We considered this more of a vanity project than anything else.  Renogy’s 175-watt panels have silver frames, which look fine, but our van is dark grey, so we opted to paint our frames black so that the panels blend a little better.  It’s a pretty easy side project; but just takes some time.

Note, we only painted the frame – not the front or back of the solar panel - which involves 4 steps:

1. 1. Sanding
   2. Masking
   3. Priming
   4. Painting

Sanding helps the paint adhere to the surface.  Using a sanding block, we lightly sanded the aluminum frame, first with an 80-grit block and then with 220-grit.  The Renogy frames have shallow grooves, so we took care to sand inside the grooves.

Also, some Renogy frames have blue plastic corners which aren’t removable.  To sand the corners, we used a Scotch-Brite pad to scuff the plastic surface.

After sanding, we wiped down the frames to remove any dust before we masked the panels.

To mask, we first covered all holes in the frame and then used builder’s paper to cover the back and front of the solar panels, which we taped in place with painter’s tape.

Before painting, we primed the aluminum frame with Rustoleum Self Etching Primer.  And to prime the plastic corners, we used Rustoleum Adhesion Promoter.

After priming, we lightly sanded one more time with 400 grit paper before spraying each panel with 2 coats of Rustoleum in Satin Black.

Afterwards, we let the paint dry for 24 hours before installing the panels.

Step 3: Installing Solar Panels on the Van Roof

Installing the panels was easy. That said, it helps to be organized.

Before installing the panels, we inserted the bolts  - provided with our towers - into the roof rail mounting track.

Next, we did some prep-work on the ground.  On a workbench, we laid out all three panels, bottom side up, in order of installation. With everything laid out, we took some time to work out our wiring diagram on a piece of paper.  The point is to have a wiring blueprint to guide installation.

We also worked out a plan for panel installation, as each panel weighs 20 pounds - just enough to be unwieldy up on a ladder.

Ideally, we would have fully mounted the towers to the panels on the ground, connecting all 3 panels together and installing them as one unit.  Unfortunately, there’s only two of us, so lifting three panels as one 60+ pound unit onto the roof would have been…..difficult.

Alternatively, we chose to install the panels one at a time, starting with the rear panel and working forward.  To facilitate installation, we partially mounted the towers to the solar panels on the ground by attaching:

• • • 4 towers to the rear panel
    • 2 towers to the front edge of the middle panel
    • and 2 towers to the front edge of the front panel

Doing this solves for 24 of the 32 bolts that fasten the towers to the solar panels.

Importantly, we left some play in the bolts to allow wiggle room for adjustment during installation.  Up on the roof, that left 8 bolts to install.

Note, there’s not a lot of room for a wrench to install the 8 additional bolts.  We found that a 7/16 ratcheting wrench significantly speeds up tightening the bolts.

Once all three panels were installed and loosely bolted to the roof rails, it’s just a matter of  tightening everything up.

Step 4: Wire the Panels Together

With the solar panels installed on the roof, the next step was to wire them together.  Before we wired them, we covered the panels to make sure they weren’t generating power. It goes without saying, but this was important. Forgetting this step will mean that you’re working with live wires.

We opted to wire in series, which made connecting them together straightforward. Each panel has two wires – one positive & one negative – w/ MC4 Connectors. Using some spare boxes to create a workspace, we wired the panels together by connecting positive to negative / negative to positive.

For added wire protection, we encased all wires in conduit, using zip ties to hold everything in place.

Step 5: Run Wires Through the Van Roof

After connecting the panels together, there’s one positive and one negative lead left over, which need to be connected to a charge controller inside the van.  To do this, we added 2 extra lengths of wire, which run through a wiring gland in the roof.

There are a couple of decisions in selecting the right wire:

• • • How many feet of wire is necessary?
    • What gauge wire should be used?

To answer these questions, we needed to measure the distance between the positive and negative leads on the solar panels and the mounting location for the charge controller. This measurement is used to determine how much wire is needed and will also help calculate the appropriate wire gauge.

Renogy has a useful wire gauge calculator on their website, which makes calculating the right gauge easier.

Selecting the right gauge wire is important, not only because selecting a gauge that’s too small can be dangerous, but also because it can reduce panel efficiency.

When in doubt go with a bigger gauge wire.

For our setup, we selected 10 AGW wire with MC4 connectors installed on one end.  This made hooking up the wires to our solar panels a plug-and-play process. After connecting the wires, only one step remained - route the wires through the roof using a waterproof wiring gland. For this, we opted to use two Blue Sea Cable Clams, which are designed for marine applications

To install the cable clam, drill a hole in the roof that’s big enough to run the wire through, then mount the cable clam over the hole, and run the wire through the cable clam.

The clam uses a gasket, which when tightened, creates a watertight seal.

To install the cable clam, we first drilled a hole through the clam’s rubber gasket so that we could slip the gasket over the cable.  To do this, we measured the wire diameter and selected a drill bit that matched the measurement.  To measure the wire, we used an inexpenisve caliper gauge.

While drilling, the instructions recommend pouring water over the gasket to help get a clean cut. Also, we spoke to Blue Sea and they recommended using a very sharp drill bit.  And, as an added tip, Blue Sea suggested placing the gasket in the freezer for a couple of hours before drilling, as the harder rubber is easier to cut cleanly.

After cutting the hole, we took an additional step: we cut a ½” piece of birch plywood into a small backing plate, which fits directly below the cable clam on the underside of the roof. The point here is to provide some additional support for the cable clam’s mounting screws, as our Sprinter’s roof is pretty thin.

With the cable clam ready, we drilled two small holes in the roof for our wires to pass through.  To do this, we drilled a pilot hole, which we expanded using a step bit. (Note that we also drilled pilot holes for the each of the cable clam’s 4 mounting screws.)

After we drilled the holes, we applied two coats of Rustoleum to each of the holes. As an added precaution, we placed 2 grommets inside our wire holes to help protect the wires from chaffing.

With everything installed, it was just a matter of running the wires and screwing everything in place before adding wire conduit.

One final note: If you don’t immediately connect your solar system into the charge controller, be sure to cap the end of your wires to avoid potential electrocution.

Our Thoughts on this Project

Installing the van solar panels was one of the easier projects we’ve completed so far

For difficulty, we’d give it a 3 out of 5 (including research) – or 2 out of 5 for just installation.

Learning about solar systems, understanding wiring, and researching panels that met our goals consumed most of our time. The actual installation was straight forward, thanks in large part to the use of Direct Mount Towers with OEM roof rails, which made it feel plug-and-play.

For Sprinter vans, the direct mount towers w/ OEM roof rails is a great combo. According to Impact Products, the towers works with solar panels with lengths between 46 and 52 Inches.

This begs the question, what would we do differently? Honestly, we probably wouldn’t change anything about this one. We’re very happy with the ease of install and end result.

Let us know if you have any questions.  If you haven't seen the video, we walk through the installation process, which might help if anything is unclear to you.

 

Van Solar Tools and Supplies Checklist

If you want to order anything for your van solar project, we've compiled a list with links to everything we used in our project, divided into categories for easy reference

Van Solar "Kit" - Includes everything you need to buy and mount solar panels on a Sprinter 144 or 170

Solar Panels (175 Watt): https://amzn.to/3rLBsfm

(Note: As a reminder, these panels are narrow enough to fit perfectly within the footprint of a Sprinter van. We fit 3 panels along with 2 MaxxFans on a 170 Sprinter wheelbase.  Measurement for 1 panel is 52.2”x26.3”x1.38”)

Roof Rails: https://amzn.to/3mn5Hrj

(Note: You will need 4 towers for 1 panel, and 2 towers for each additional panel (so, 4 towers for 1 panel, 6 towers for 2 panels, 8 towers for 3 panels, and so on).  The towers come in sets of 2.  We have 3 panels, so bought 4 sets in total (for a total of 8 individual towers)

Solar Charge Controller: https://amzn.to/37v8xVj

 

Solar Panel Installation

Ratcheting Wrench:  https://amzn.to/3tTAdwN

Gorilla Ladder: https://fave.co/394Sm2a

 

Solar Wiring

10AWG Wire: https://amzn.to/3db1u81

Wire Conduit: https://amzn.to/2LO4NGG

BlueSea Cable Clam (x2): https://amzn.to/3d8SK1Z

Jigsaw: https://amzn.to/3w7ZofS

Jigsaw Blade: https://amzn.to/3dgB42O

Primer Paint: https://amzn.to/3qACzOF (to treat bare metal edges)

Small Foam Brush: https://amzn.to/3qu8T5I

Mineral Spirits: https://amzn.to/39KbNwn

 

To Paint the Solar Frames

*For Plastic Corners
Heavy Duty Stripping Pad: https://amzn.to/2OpPiFP

Adhesion Promoter - https://amzn.to/3rOm6GS

*For Aluminum Frame

Sanding Blocks: https://amzn.to/2Nho0kH

Self-Etching Primer:  https://amzn.to/2Z5X2z4

Spray Paint: https://amzn.to/3ael1T8

Painters Tape: https://amzn.to/34j9iOP

 

Safety (for painting):

Eye protection: https://amzn.to/35Niz32

Rubber Gloves: https://amzn.to/2NfT0Bx

Respirator

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