Adding a portable 100 watt panel


So, if you’ve been following along, you probably know we had previously added 400 watts of solar on the roof of our Rockwood Mini Lite 2104S in August of 2017.  Following that install, we added another 200 watts last spring.

So why would we need MORE solar for our camper ? Reasonable question, but it boils down to having the flexibility of another 100 watt panel that we can move away from the camper (and not permanently attached to the roof) and place it in the sun.  This is handy if we want to park under some trees or shade OR if we just want to take advantage of the early morning sun, and/or late afternoon sun.  These are times when our roof panels aren’t getting much sun (they are mounted flat, with no tilt mechanisms).

We already had a port on the passenger side of the trailer that was pre-installed by Rockwood.  This was for a pre-wired Zamp port, which was essentially just an SAE connector, something sorta like this :

The Zamp pre-wire from the factory is really just a marketing thing, that… I suppose might help some folks out.  But… a few things that stink about the Zamp panels :

1)  the pre-wire for Zamp is backwards polarity.  Yes, they “trick” you into using their own proprietary panels by flipping the positive and the negative on these SAE connectors.

2) they are very very expensive for what you get.  here is one 80watt panel for over $400 !  I’m sure there are cheaper Zamp panels, but when I have priced them in the past they were at least 3 – 4 times (if not more) expensive than excellent panels from other respected brands.

3) they generally have their controller integrated into the panel.  this is fine for a 1 panel trickle charge system, but this makes them harder to integrate into a bigger array.  I get it, its supposed to be plug and play for folks but this is pretty limiting.

4) in our case, the prewire was very light gauge, probably 12-14 gauge or less.  This means less power output from the panel into the battery

So, basically, this is good marketing by Rockwood, helping to make a great sales pitch by saying this camper is “Solar Ready”, that is, so long as you don’t mind getting roped into using Zamp’s panels OR hacking their port, flipping the polarity on your own panel and being OK with light gauge wiring.  Its probably more accurate for them to say “Solar Ready to trickle charge your default lead-acid battery”

So, back when I did my first install with Eddie , I had him just cut out that pre-wire (since it was wired directly into the old battery wiring harness).  We basically just chopped the Zamp pre-wire, right along the inside of the new battery compartment.  Knowing that some day we’d re-purpose that port for something more useful.

On a recent trip to see Eddie with a friend of mine who was getting some work done on his Airstream, I was able to steal a tiny bit of Eddies time on the Airstream project to help me install  a new port in the spot that had the Zamp pre-wire from Rockwood.

I got the idea somewhere in this blog post from Ray at Love your RV, Ray shows how he used a special port to connect his Viair Compressor:


I liked the idea of this port mostly because it was meant to be used in a wet location (it is for a boat motor after all).  In our case, the factory installed Zamp port is to the right of the storage compartment that has our batteries, solar controller, shunt etc.


This is an OK spot for it, especially because the wiring run from the inside of the receptacle to the solar disconnect box is very short, about 8 inches  (the shorter the run, the less power loss).  However, there is a roof gutter above this port and above the battery door.  When the battery door is closed, its sealed and no water is getting in (so we dont worry about the battery / wiring etc), however… with a heavy rain and heavy wind, I’m worried about water getting into a “normal” / not water resistant port (such as the Zamp pre-wire), especially while connected to a live solar panel.

So, Eddie pulled out the Zamp port, and replaced it with the new Minn Kota port. This required enlarging the existing hole created for the Zamp port.  He then wired up the port to the solar disconnect box (which had available terminals available from the original solar install), using the diagram for 12v (1 neg 2 pos).  This way, when the extra portable panel is connected and adding power, it will just be added in to the solar controller and be part of our main array.

here Eddie is demonstrating via a meter that he has properly connected the positive and negative as per the wiring instructions for the plug receptacle

Due to time constraints for the Airstream project, we left the new port “as is” and the rest of the project was left for me to complete.

First things first, we needed a new panel to use for this project.

I went with a Renogy 100watt flexible panel .  I was able to get this panel on sale for $50 off retail, but its still very expensive for a 100 watt solar panel.

However, this panel only weighs 4lbs, is very thin (easy to store inside our camper)

Panel Dimensions: 47.9×21.0x0.08 In

This panel also has a very good warranty compared to other flexible panels on the market.  From Renogy’s site:

100 watt Flexible Panels 25-year power output warranty: 5 year/95% efficiency rate, 10 year/90% efficiency rate, 25-year/80% efficiency rate

5-year material and workmanship warranty

Next I ordered 20 feet of 2-wire #10 awg wire , which is the same wiring we ran on the rooftop panels because, according to Eddie and Northern Arizona Wind and Solar :

“the standard wire for all outdoor and indoor solar panel wiring applications. Commonly used for PV module wiring. Water and sunlight resistant.”

Eddie suggested that 20 feet of #10 would be about the maximum we should use so that we don’t cause any loss in power transfer from the panel to the array.

This wire has worked well so far on our rooftop, so we went with this again.  I decided to build my own mc4 connectors instead of permanently connecting the new #10 wire to the panels.  Why ? well :

  1.  I wanted to be able to disconnect the wire, wrap it up and store it without it getting all mangled on the flexible panel or in a storage compartment.
  2. if I happened to be camping with someone who needed some extra power, I could let them borrow the panel and they could just connect with standard mc4.

I haven’t created an mc4 connection before, so I did some googling and found these two gems :

The “marine how to” blog recommended NOT cheesing out on cheap mc4 (to minimize the risk of an unreliable/not water tight connection), so I bought some Renogy mc4 connectors, a special tool to make the mc4 crimp, some heat shrink that was big enough to get around the #10 2 wire (3/4″ shrink tape) and some heat shrink for the positive and negative wire once the mc4 connectors were done.

step 1 :  strip back some of the insulation / outer cover of the 2 wire


step 2 :  grab one of each of the mc4 connectors.  note ! the metal contact / crimp section of the connector has 2 sizes.  The LONG metal crimp one goes in the SHORT connector (in this case colored red).  The SHORT  metal crimp goes in the LONG connector.


step 3 : strip back enough of the wire so that the #10 wire can fit into the metal crimp, but not TOO FAR, or else ,when you try to make your connection with the mc4, there won’t be enough room to push the two together and make the connection “click”

note, dont forget to put your heat shink tape on first, then the connectors

step 4 : make the crimp. it helps to pre-crimp or get the wing of the metal piece to start and curl before you really clamp down.  The picture below shows me using the 6mm die, but actually, I got a better connection using the middle die (4 mm)


step 5 : once you crimp the metal piece onto the wire, push the metal piece into the mc4 connector and it will “click” into place.  you can now screw the connectors together.  (by the way, the two linked how-to’s are a bit more detailed).  Some mc4 tools are handy for the final step of screwing down the connection tight.

one major mistake I made on my first connection :  I actually connected the red (positive) mc4 (short) to the red lead on the 2 wire #10 awg wire.  That unfortunately did NOT work, naturally, because the Renogy panel has the red mc4 (short) connector.  So, I really wanted the OPPOSITE.  So for me, I connected the long mc4 (normally negative) to my positive wire, and the red short mc4 to the negative (black) wire.  This way, when you connect to the mc4 on the panel, the polarity will be correct.

suggestion : buy a few more connectors than you think you’ll need, because you are unlikely to make a proper connection on your first try.  Trust me, I botched my first 2 tries, not to mention my incorrect polarity blunder mentioned above.

Next :  correctly wring the Minn Kota.  I just needed to disassemble the plug, which in the picture below, shows a two part system.  A rubberized jacket, and a hard plastic harness inside (plus a small routing bracket).   The holes in the back of the harness are numbered, to match the wiring configuration that Minn Kota recommends, the same as Eddie did above. (1 neg 2 pos)


once the wires were in the right numbered hole in the back of the harness, you just tighten down the screw to hold them in place, and replace the jacket in the correct alignment.  In a few pictures I’ll try to show the alignment piece of this connector (it only makes a connection in one alignment)

here is my finished connector
here, i have connected my new wire to the solar panel via mc4, and I’m testing the polarity of the  blades on the Minn Kota to be sure I’m getting positive and negative as expected (and getting juice from the panel)
its a little hard to see in this picture, but there is a downward pointing triangle on the mounted part of the Minn Kota port, and on the connector, there is an embossed “INSERT” on the top of the connector.
here, if you look carefully, you can see a rubber o-ring on the connector.  you have to push past this ring to seal the connection, then turn clockwise to lock it in place.  the o-ring creates a nice water “resistant” connection.
here is the new connector in all its glory, locked into the Minn Kota port

So… how’d it work ?

well,  luckily for me, I wired things correctly (the first time) so that the positive and negative matched Eddies install of the port.  We connected the panel to the new Minn Kota port and immediately we were getting more watts / amps into the array !  This Renogy Flex panel really puts out some power !

On our most recent trip, we were camped under some huge Cottonwood trees, so we were actually getting most of our mid day solar from our new portable panel.

it works really well !




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