Added Solar Capabilty to the Van

A 235 watt solar panel to make boondocking easier. This photo was taken from Dad’s house roof.

For those wishing to boondock for either a day or a season, nothing beats an on-board solar panel system for coddling your house batteries.

Though I have a generator, it does use gas and necessitates me being in close proximity to the van. People love to steal generators – especially Hondas. The generator is great for high current applications such as a toaster oven or microwave but it’s kind of a waste to use it for trickle charging batteries.

The other problem with the generator is there is no “real time” charging. Even a car alternator can only charge when burning fuel. Instead of having to wait to charge the batteries, now they can receive some kind of charge all the time, if needed. Solar will also save running the AGM batteries down when forgetting to plug in shore power or leaving the Koolatron on









Once very expensive, solar prices have been coming down to some degree. If you can do it yourself, you can save a great deal of money. After having watched the costs drop, I jumped on a deal on the Astronergy 235 watt (30-34V), polycrystalline panel. Only one panel was desired though at the time I didn’t realize how difficult it was to wrestle something this big! (Roughly 39″ x 54″)
At the same time, I ordered a Chinese made (despite better judgement), no-name MPPT solar charge controller. For those unfamiliar with solar, a charge controller simply takes the incoming solar panel energy (which can vary quite a bit all the time), and while monitoring the battery charge state, regulates the charging current going into the house battery bank. Without this controller you can overcharge and destroy the batteries.

So here is how it all was fit together. On the roof rack, I added two green treated 2×4 boards running lengthwise. They are clamped to the rack with u-bolts. I could not paint or stain the boards yet because the treated lumber is repelling water and other liquids.
The next step was to install the Z-brackets to the bottom of the solar panel. They keep the panel secure but elevated a little. It is better not to flush mount – air circulation is desirable. When hot, solar panels lose efficiency.
The dealer sold me one set of four Z-brackets like you see in the photo. I purchased an additional set. That turned out to be a wise decision. Holes were pre-drilled in the aluminum frame to accommodate three brackets on each side for a total of six. Had I bought only the set of four, I would have been very upset! I was able to use six and still have a couple extras.

In this picture, the panel is face down on some cardboard on the ground. The white surface is the back side. I was told by the vendor to be very careful not to damage the back because it is more sensitive to scratches than the front. I babied it!

Once the panel was ready to mount, I rechecked the spacing on the 2x4s on the roof. Their separation was adjusted a little. Outside edge to outside edge was 43″. That gave me some room to center the feet against the 2x4s.
Then I wrestled the panel up onto the roof and set it in place. Attaching it was easy. I simply drilled 6 holes, one through the 2×4 in the place where each Z-bracket sat. (Note – the Z brackets are pre-drilled making it very easy to drill into the wood). Then I fastened the feet through the 2x4s using 1/4-20 bolts, washers, and lockwashers. Originally I used standard nuts. I’ve decided to replace them with nylon locking nuts. After all, this contraption needs to go sixty miles per hour. Coming loose must not be an option.
It was incredibly easy to do the wiring. A coil of 30′ of solar wire (stranded copper with two kinds of insulation) with two MC4 connectors was purchased. You just cut it in half and use it for both leads coming in. There was enough leftover to wire the charge controller to the battery, too!
I purchased a 7/8″ hole saw for the drill and cut a hole in the roof. I used a heavy plastic snap bushing in the hole and routed the + and – cables through the roof and into the area behind the passenger’s seat.  I caulked the crap out of it.   One thing about passing the cables through a hole… I may change that snap bushing to something metal for durability.
With two wood screws, I then mounted the charge controller on the wall behind the passenger’s seat. It was more convenient to have it up front near one of the AGM batteries. Besides, with a panel voltmeter in the sleeping area, I can always monitor the charge level without needing to see all the details.  
Inside, there were four wires I had to deal with, + and – for the solar panel as well as + and – for the battery. #10 solar grade wire was used and the four connections were made.  I couldn’t find my roll of red tape so while at the Home Depot, I snatched a couple of red paint sampe cards from the paint department.  Then I put a little piece around each of the two positive wires to color code them.  It grates on my nerves to have two black + wires and two black – wires….  It’s just wrong!
After connecting up the panel, the charge controller immediately came to life and indicated that there was solar energy and that the bank was in “charge mode”.  (Left side – blue and green LEDs)
If you look at the front of the charge controller photo, you can see a number of pieces of information.

63 watts are going in at this instant. This is what is being allowed to pass through to the batteries, not what the outside panel is creating. (sort of like counting gallons per hour coming into your home at any one time, not how many gallons are in the water tower or the water pressure of it)

The 13.5 V on the lower left is the charging voltage at this time (absorption rate) that is being applied to the batteries. You can see that 4.2 amps of charging current is replenishing the batteries. When full, the current will drop to zero even if there is a bright sun. The charge controller is doing its job as a sort of “traffic cop.” It either restricts flow or says “Halt!” as needed.  When the sun goes down, it will prevent reverse current from going back into the panels. 

When I first fired up the charge controller, I thought it was busted! The batteries were at 100% charge and the controller didn’t allow for any charging. I ran a bunch of current hogging devices for an hour. Like a dumb ass, I locked myself out of the van and had to look for a spare keys! (I had taken off the magnetic keyholder some time back)

By the time I found a key, with all the loads running, the controller had changed to a bulk charge phase. According to the panel, the two AGM batteries were now getting fed 11.5 amps of current from my 8 amp rated panel.

How can that be? A 235 watt panel that is rated for 30V generates about 8 amps of current max. Watts’ law says that power = current x voltage. (235 watts = 30 Volts x 8 amps).
Here is where MPPT shines. The old style charge controllers only clip off the voltage above 14 or so volts. That means that 14 volts times 8 amps means you can only get about 112 watts of power maximum from that 235 watt panel! Much is thrown away. What a waste!

Updated on 04/11/2012… After a week’s use, I’ve reguarlary watched 190-200 watts being utilized during peak sunshine hours!

MPPT is more efficient at converting energy from higher voltage panels. MPPT technology does not waste the excess. It would be a different story for a smaller panel. If your panel only kicks out 17 volts it’s not really worth the extra bucks for an MPPT controller because there’s little extra to harness. If charging a 13 volt battery with a 34 volt panel, I would be throwing away the extra 21 volts using the older technology!
As you can see, I’m freaking delighted at the extra 43.5 percent current being utilized from the panels thanks to the charge controller. That’s actually higher than the average savings for an MPPT system and probably not something that will be seen all the time. Nonetheless, it made me glad that plenty of time had been taken to research the different types of charge controllers and buy one that was a perfect fit for the need. It’s going to be fun to use on the road, too.
Here is another shot of the Trekker Van. You can see something on the roof but it’s hard to tell it’s a solar panel. The bottom surface is white. The plan is to add some small trim on the sides that shields the panel from people on the ground but does not at all shade it from the sun.
Well, I hope this post was of interest for those who are considering solar technology. It’s not that expensive, works great, and is easy to install. The whole project took just a couple of hours to do once I got going.
Please feel free to email or comment with questions about solar or any other topics.  There are also plenty of knowledgeable folks on the Cheap RV living forum as well. They helped me and I’m happy to pass the favor along to others. We learn from each other and by doing.
Have fun and thanks for stopping by!

About VanTrekker

I am a former vandweller in Eastern Iowa who, for several years (off and on), lived in a 2007 Chevy cargo van. I still travel around Iowa with my tortoise shell cat, Jennifer Stefanie. Our favorite place to explore is the Country Heritage Community, the four far northeastern counties of Iowa (Clayton, Winneshiek, Allamakee, and Fayette). Ride along as we fish in pristine trout streams, enjoy fine home cooked camping meals, and meet new people. It's all possible on a shoestring budget. Happy travels always! --- Brad, the "Van Trekker"
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11 Responses to Added Solar Capabilty to the Van

  1. Anonymous says:

    Brad,

    I enjoyed reading and viewing pics of your solar install. I plan to do something very similar to a step van or a cargo trailer as I get my build underway.

    The informatioon on the cheaprvliving forum is priceless, and it’s great to hear YOUR SUCCESS STORY.

    Bob(AKA Stude53)

  2. If someone had two panels each feeding ~17 V, wouldn’t they hook them up in parallel? I can’t imagine a reason to set up in series and waste half the incoming.

    235 is a nice size! You should be able to do what you want, pretty much.

  3. Anonymous says:

    I’m about to embark on a similar project and I’m torn between direct roof mounting or cargo rack, like yours. Have you noticed any aerodynamic problems at highway speed with the panels that far above the roof?
    Thanks for sharing the how-to.
    David Greybeard

  4. Brad says:

    Thanks for the comments!

    Bob – Glad to hear so many people are going solar. It’s probably the best upgrade of all the van projects. I’m excited about ability to boondock any time, any where. You’ll enjoy it!

    Good Luck Duck – Yes, you would use a combiner, essentially putting them in parallel. I could have done that but ended up just getting a larger panel instead. Either way will work. If you put up two smaller panels, I would get a less sophisticated charge controller – just a PWM since there won’t be that much extra energy to “recycle”.

    David – I need to finish things up a little more (add cable ties, recheck hardware, etc.) The plan is to do a roadtest today and I’ll get back to you a little later today regarding how it does at highway speed. The only thing I can see maybe happening is adding a third 2×4 if it gets to vibrating at the front end. The frame is very strong and rigid but you never know till you try it.

  5. Brad says:

    David,

    I took the van out on the interstate and got her up to about 70. So far so good – no new wind noise at all. So far so good.

  6. Ryan McCoy says:

    Brad, I haven’t commented before but I just wanted to say this is one of the best summaries of solar power that I have seen. Just started the whole vandwelling thing but I will reference this if I ever consider solar. Hope it works out for ya!

  7. Brad says:

    Thanks Ryan. I look forward to hearing how it works out for you. Solar is so cool and virtually maintenance free.

  8. Pleinguy says:

    Niice job on the solar panel Brad. I’d think twice about closing it in underneath. You want airflow below the panel to assist cooling; makes it more efficient. Viewing from above you can see it is a PVP, but from street view I suspect folks would just take it as a platform (perhaps meant for a pod). Hope it provides many hours of off-grid camping.

  9. Brad says:

    Thanks for the note, Pleinguy… There’s not doubt it’s a polycrystalline solar panel with the different shades of blue – it’s a dead giveaway. No, I don’t plan to close it in underneath… Having it open is important. Today it was putting out an impressive 200 watts which was pretty good considering its size.

    The most I might do is secure a little 1×3 side trim (back an inch or two or so from the edge) around the aluminum area to block it from view. The whole bottom surface would be uncovered as well as front and back. I’m still toying with the idea of a couple of 10′ long 4″ black pipes for water storage on either side…

  10. Hi Brad

    First congrats on the weight loss…supper good job your doing.
    I was looking at your panels 39*54″ and said wow so small ? as i’m looking for smaller panels that size, since my 210 are 39x 59″.
    Checking the specs I saw they are 39*65″ which is what I was thinking.
    I am also shocked that you would get 200 watts laying flat – in April …just amazing as the panels are normally rated 160 NOCT at 25 deg C ….well I guess you could get 200 watt if it was very cold in Colorado or high in the mountains. At noon on a 80 deg day you would never pull that much power as the panels are over 100 deg already. Higher temp is lower output.

    Im also blown away that your 9,000 Btu single hose unit cools like you say in a few minutes. I tried a 7,000 Btu single hose LG in my insulated 7 x 16 Cargo trailer and the results were poor. I did reverse engineer “hack” a 5,000 Btu window ac to install on the roof with a blower fan & that does kick butt !! I installed my 4 x 210 watt panels with VHB tape & a front spoiler – but have not road tested yet – however I got the idea from Glenn on http://www.tosimplify.net/ . Im thinking to add a few more solar so that my ac can run 100% on solar …..I just love that ac.

    Keep up the good work loosing weight….I’m fighting that battle too

    Jerry

    http://overthetopcargotrailer.blogspot.com/

    • Brad says:

      Hi Jerry,

      Thanks for the comments. I’m camping tonight at Anytime Fitness in La Crosse, Wisconsin. Just had a superb workout… Then ya just go outside and sleep like a baby after a nice shower. What a life!

      The solar panel is still getting 200 watts on a regular basis but I see it starting to drop off a little as the Iowa days are growing shorter. Still, it’s given me days of enjoyment at a time with no shore power needed.

      The A/C also does a great job but I’m cooling a lot less space – a standard height van that is well insulated in the floors, walls, and ceiling. It is also only about 6 x 9 feet inside with the bulkhead wall. On the very hottest of days, it would get comfortable in ten minutes and quite cool in 20. Relief was almost immediate.

      Keep fighting the weight loss fight. It’s definitely worth the work. Thanks again for the kind words!

      Brad