300 W on a 2720SL -- 2 flex & 1 rigid

[klpauba]

I would like to share information on my solar install. I'm getting it all ready for boondocking on the north shore of Lake Superior the last week of July.

I can't really take much credit for the design -- much of it came from this forum and one member in particular, rickst29.

I'm installing an array of 3x100W panels -- 2 of them are flexible (mainly to keep the weight down) and 1 rigid panel straddles the center seam of the rear shell. The performance characteristics of the rigid matches those of the flexible panels pretty closely so it works out well. The panels are wired in series to produce a maximum voltage of about 50V and maximum current of around 5.5A The panels feed into a EP Solar Tracer 2215BN that will charge the two GC2 batteries (225 AH).

I opted for 3 panels to offset the energy loss since the panels are mounted flat on the shell and not able to tilt for maximum insolation.

At this point, I have the two flexible panels attached -- I'm waiting on some video/power cable to arrive tomorrow so that I can attach a video camera to the aluminum frame of the rigid panel before I install that one.

I first installed some Cordmate III plastic wiring channel just behind the bag seal and down the street-side window. Nothing new here; there are plenty of posts showing how others have installed this to hold/hide the wiring.

Following rickst29's suggestions, I used 3M RP32 adhesive tape to attach the flex panels. I pulled the protective covering of the tape at the ends of the segments so that I could easily pull it off as I was laying the panel down:

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After I cleaned the shell surface with Awesome Orange cleaner and 50% alcohol solution, I put the top of the panel against the wiring channel and carefully pulled the protective covering off of the top strip and pressed it down. I was able to hold the flexible panel up with my bald head and one hand while I progressively removed the protective covering off of the next set of tape segments. This made attaching the panels by myself relatively easy.

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I then used a rat-tail file on the wiring channel to provide a place for the panel wires to enter the channel. I repeated all of this on the other side of the shell and here's the result:

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Boy, after cleaning the portion of the rear shell, the rest looks especially dirty. I guess I'll be doing the same on the rest of the trailer!

Tomorrow I plan on attaching the rigid panel provided some additional materials arrive in the mail. I'll continue the thread then.

[klpauba]

My parts were a day late coming so I didn't get to installing the glass panel until today.

The glass panel is mounted on 4 z-brackets supplied by Renogy (as suggested by rickst29). The 3M tape was affixed to the brackets and anchored to the roof. I carefully cleaned roof with the Awesome Orange cleaner and 50/50 alcohol solution where the brackets would come to rest. Here's a shot of all three mounted:

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These three panels add just over 25 lbs to the weight of the rear shell so there shouldn't be too much difference in lifting it.

As mentioned in my earlier post, I used the CordMate III channels to hold all of the panel and camera wiring. Here's a shot of the wire channels holding all of the wires.

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I must say, it's very difficult to close the channel cover wherever the MC-4 connectors are located. I hope they'll stay closed. I also plan to apply some caulk/adhesive where the channel meets the roof to make sure it stays there.

I need to pick up some screws to mount the backup camera tomorrow. This little camera was previously used on my TV but it was mounted in a location that was often bumped. I used a different camera that better resembled an OEM installation so I had this one as an extra. I've run the video cable up to the area of the electric jack where I'll be mounting a wireless transmitter in a PVC (waterproof) electrical box (which will be pipe-clamped to the jack tube). The transmitter's power will be manually switched on and the TV camera (which uses another identical wireless transmitter) will be switched off. In that way, I can choose which backup camera to view (TV or trailer) on the screen between the driver and passenger seats. Here's the trailer backup camera as it exists now -- it will be attached to the glass panel frame:

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Next, I'll be routing all of the wiring to the street-side lift arm and getting them to the rear "electrical room".

[CAG1976]

Genius on the back up camera being mounted to the solar panel. I want to do both mods and know I can get both done at the same time!
Nice job.

[tentcamper]

very nice installation. I like the flexible panels.

[Shane826]

That looks about as close to "looks like it came from the factory" as it gets! Very nice job!

[klpauba]

Thanks all of you for the kind words.

I got a PM from rickst29 mentioning that I should make sure the panel ground must be grounded and not be on a connector. I'm cutting off the anderson connector and take his advise for safety's sake. Glad I have his support along with all of the rest of you folks on the forum.

Been in the 90's with 80%+ humidity here so I'm not getting as much done as I'd like. I was able to route the wiring in CordMate III down the lift arm. I ensured I had enough extra looped at the shell/arm joint by opening and closing a few times. I also affixed the backup camera.

I'll be working on getting the ends into the rear compartment next. Pictures to follow.

[klpauba]

Here's a bit more detail on the wiring that runs from the panels to the rear battery compartment.

I ended up using a heat gun in the vicinity of the panel MC-4 connector (the positive line coming from the street-side flex panel). I couldn't get the CordMate III to snap closed. You'll notice a bit of waviness of the surface but at least it closes now.

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The CordMate III included enough connectors for everything but I ended needing a few more feet of channel so I bought another "kit". I used up some of the "joining" connectors (I think that's what the directions called them) for re-enforcement. When things are all connected, I'll probably put a little caulking to help keep them in place. I think I'll also take some white cable ties and cinch them around the lift arms to help ensure they won't go anywhere. They look a bit dirty but if I have time before a trip on 7/22 I'll give them a shot of white Rustoleum Fusion plastic paint.

When the channel reaches the bottom of the shell, it makes a turn toward the front of the trailer and terminates at the pocket stop. At this point, the wires become exposed to the elements as they loop to the lift arm. I used some spiral wrap to keep the wires contained (picked the wrap up at Home Depot close to where the CordMate III was located). I open and closed the rear shell to make sure there was no binding of the wiring bundle .

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I again used some spiral wrap on the bundle of wires where the channel terminated at the torsion bars. I loosely secured the wrapped bundle to one of the torsion bars. You might be able to make out the dark video cable from the camera that separates from the others and heads up inside the street-side rectangular frame member to the hitch area. The remaining wires make a u-turn into the street-side rear bumper area.

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My next step will be to cover the solar panels so very little power is on the wire. Then I can safely fish the three wires into the rear battery area that I call the "electrical room" and make some terminations. Before I do that, though, I'll need to program the MPPT controller for the proper charging of the two Trojan T-105's.

[inghamm]

Nice job! Did you get the MT-50 Remote Meter LCD Display? I love mine.

[klpauba]

Yes, inghamm, I did get the MT-50 and spent what little spare time I had last night programming the battery settings. I like it too -- the default display will show me all important information at a single glance.

I didn't have much luck getting the wires fished from the bumper to the rear compartment, though. The flex conduit that I have running between the two areas just doesn't have the room for the new wires. I'll have to punch another hole.

[Padgett]

Nice job. My two 100W panels seem a little larger than yours and both are like your center panel, raised slightly off the surface of the roof so air can circulate under and keep the heat of the panel off the roof.

Mine add 33 lbs to the top of the module. Today I think I'd go with a pair of the 150W panels. (https://www.renogy.com/renogy-150-watt-12-volt-monocrystalline-solar-panel/#tab_prd-specs) though a bit heavier (53 lbs for two).

[klpauba]

Thanks, Padgett. I've read many of your posts for inspiration on this (and other) mods.

I had actually purchased the panels early last year but didn't get around installing them until now. I figured if I didn't install them soon, technology would pass them up and I'd then direct my attention to the new stuff. I really wanted to put them to good use. Last summer I committed to a camping spot without any hookups so that finally got my butt in gear (and I leave in 10 days! :eek:)

[Padgett]

You are welcome.

[klpauba]

Late last week I got most of the solar system wired up. I ran solar power wires to the controller -- the positive line is interrupted only by a DC breaker used as a disconnect switch. Here's a shot into my electrical room as it stands for the solar testing:

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I've seen 200-210 Watts coming from the solar panels (as reported by the EP Solar MP-50 display) as it sits in my driveway. Unfortunately, I have a blue spruce SE and a mid-sized maple tree SW of the TM so I only have only an hour or two of unobstructed sun around solar noon. I might sneak away at lunch one of these days to add more loads to see how the panels and controller perform if there's suitable sunshine.

I'm currently working to add the remaining components that will allow my TV to provide an alternative 24VDC charging source to the solar panels (there's another thread on that).

I'm feeling the pressure in getting this all done and preparing for a 10-day trip on Saturday!

[klpauba]

I finished up my wiring of the controls that allow me to use a booster in my TV to supply 24V through the Bargman connector to switch the input to the charge controller from the solar panels to the Bargman power connection. Using a process outlined by rickst29, I've verified that I can supply very near the 280W of power from the TV.

Just a few days ago, I found that I was getting more than 200W of power. A couple of days later, a load test of the solar system showed 180W and today I wasn't getting anything (13.1V at 0.00A !!!). Rickst29 has given me instructions to help identify the faulty panel(s). I tested each of them before installation and I shutter at the thought of trying to remove even one of them since the VHB tape seems to work really, really well. This is all happening just two days before I leave for our no-hookups campsite. At least I have the TV Booster and a 2500W genny as backup but I wasn't really planning on using them.

[klpauba]

I was able to isolate the bad panel -- it's one of the flex. I wired the other two in series so I'm now running at 200W. My next step will be to open up the junction box at the top of the panel and check the bypass diode. If that checks out OK, I'm probably stuck with trying to replace the panel.

Let this be a lesson to others. Don't delay installing your panels so that you miss out on the warranty!

[BrucePerens]

If you are lucky, it's a diode, and it's in a junction box that you can open.

I remain dubious about the lifetime of flex panels on a trailer roof. It gets hot and there is no no heat flow from the back. Photovoltaic cells don't like heat and lose efficiency in operation when hot, and maybe break more easily as well. I am dubious about Elon Musk's solar roof for the same reason.

Use framed panels and feet that you can remove them from, and leave room for air flow behind them. Yes, they are heavy, but they last and can be serviced.

[Padgett]

BTW no reason you cannot just set outside, wire up temporarily to a battery and test operation then install. Lots easier to work on before installed on roof.

Mounting a wireless back up transmitter for back up camera with type F antenna to the panel (offset from AC) gives line of sight to the TV. No more wiring needed.

I prefer monocrystalline panels to poly. Cost a little more but have better performance when hot.

[scrubjaysnest]

I was able to isolate the bad panel -- it's one of the flex. I wired the other two in series so I'm now running at 200W. My next step will be to open up the junction box at the top of the panel and check the bypass diode. If that checks out OK, I'm probably stuck with trying to replace the panel.

Let this be a lesson to others. Don't delay installing your panels so that you miss out on the warranty!

This is a nice install; with regards to the bad panel......a quick and dirty check before installing is place the panel in full sun not wired up. Check the open circuit voltage, it should be Voc for the panel. Next short the panel and you should get very near Isc for the panel. These test will not damage the panel.

Let me know via pm if you want your install added to the owner install thread.

ken

[klpauba]

... I did the Voc test when they first arrived but didn't realize I could short them without damage. I'll add that test when I get around to it this weekend.

I then plan to remove the bypass diode and test it as described at http://http://www.ebay.com/gds/How-To-Test-a-Schottky-Diode-/10000000205730702/g.html.

I'm open to other suggestions from anyone so please offer them!

[klpauba]

... a small circuit board. The board was potted but it didn't seem to be epoxy. It flaked away pretty easily. It's hard to see, but two small ring terminals are at the very left and right sides of the plastic box (the screws holding them to the board are removed and shown near the center of the photo). The three large globs of solder connect the three power tabs from the string of cells (2 of them, I suspect) and the surface-mounted diodes are between them.

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The positive line is on the right so I think the arrangement of the diodes would be like this:

(-)--*-->|--*-->|--*--(+)

Where (-) and (+) are the negative and positive wire connections, * is a power tab from the string of solar cells and ->|- is a bypass diode.

Can someone verify this?

Since the circuit board isn't really serviceable, is there any easy way that I can test the diodes on the board? I plan on cleaning up the power tabs and soldering diodes directly to them (and the wire connections). I measured the open-circuit voltage (Voc) of the panel at around 18 volts today in bright sunlight (the spec says 21.6) and I shorted the panel and read just 0.48 amps (way off from the 5.62 on the sticker supplied with the panel).

Ebay has US-sourced schottky bypass diodes (15A) available. I'll wait to hear any comments that you might have before I order them on Monday (I have to buy 10 at about $1 each).

Thanks

[Bill]

Since the circuit board isn't really serviceable, is there any easy way that I can test the diodes on the board?Sure. You have a voltmeter. I assume that it is a multimeter (DVM), and has an ohms (resistance) function.

First disconnect one or both wires from the circuit board. Set your meter to one of the low ohms scales, maybe X1 or X10 or even X100. To confirm that the meter's battery is good, short the probes together and look for a reading of zero.

Now put one probe on one end of one diode, the other probe on the other end of the same diode, and note the reading. Make sure that the probes make good electrical contact in spite of any lingering goop. Now reverse the probes, and again note the reading. One of the readings should be very low, maybe a couple ohms. The other should be very much higher, but not necessarily infinity. If those are the readings you get, then the diode is good. If both readings are very high, then the diode is an open circuit, and must be replaced. If the reading is very low in both directions, then the diode is shorted and must be replaced.

Now do the other diode.

BTW, your photo didn't come through.

Bill

[klpauba]

Thanks, Bill. I checked the diodes and forward biased I see 1 and 2 ohms, when I reversed bias them the reading is 10-15 Megohms. So I suppose they are OK.

Guess I'll have to replace the panel.

[klpauba]

Armed only with a plastic putty knife (a 4" one), I was able to separate the flex panel from the TM roof today. It wasn't easy but it wasn't as hard as I thought it might be -- it only took about 30 minutes.

I was surprised that the paint from the TM roof seems to have transferred to the solar panel (see photos) and is discolored. Since the tape prevented the panel from moving, the heat must have cause it.

A new panel will arrive next week. I'll be using much less VHB tape installing it.

If you're thinking of doing an installation like mine, I'd consider Bruce's suggestion of using all glass panels. I'm replacing the flex because I don't (yet) want to remove the working one and wish to keep the shell balanced. Should this replacement flex fail, I will either live with 200W (with only a slight imbalance) or replace both flex panels with glass. If the replacement doesn't fail (and I got a defective one by luck of the draw) I'll probably endorse its use as long as they last -- only time will tell.

[klpauba]

Here's the results of my testing the new panel for open-circuit voltage (Voc) and short-circuit current (Isc). At Voc=20.31V and Isc=5.98A (with the protective clear covering still on and on a day with scattered clouds), I'd say this one will work -- ideal condition specs are Voc=21.6 and Isc=5.97.

Just a little shipping damage at a corner that messed up an eyelet but didn't encroach on a solar cell. I think I'll keep it.

Waiting on some more VHB tape to secure it to the roof.

[klpauba]

The new panel is now installed. Today I tested the 12V system under a load of about 800 Watts and the PV system was putting in over 200 W (and about 98% of that was getting pushed into the batteries).

I'll stop posting to this thread now unless someone has more questions.

Thanks for following!

[keysbottles]

Hi, I bought a 2720 (2003) last year and have been considering installing flex panels on the roof. The flex panels have been receiving bad publicity lately and I wondered how yours are holding up. I prefer flex because of the weight and ease of install. I would be interested in your thoughts. Thanks Don

[klpauba]

So far, the system has been working well. I'll be pulling out the TM for another trip and I"ll try collecting some hard data for you. Expect a more detailed response in a couple of weeks.

[rickst29]

I've had no issues with the flex panel, now about 3 years old. All my panels are mounted on the front of my 2619, with the heavy "glass" ones mounted as far back (towards the air Conditioner) as I can put them. In spite of that mounting, the front-most pair of torsion are maxxed out - I woudn't be able to lift the front shell if I had used 3x glass panels.

Glass has superior durability, especially for hail damage. But my own flex has worked out really well: 30% more powerful than each of the 100W glass panels, and problem-free. (But Bruce knows a lot more about this stuff than I do, and YMMV.)

[keysbottles]

Thank you both for your response. I have rough measurements of 46.5' x 86" on the back slide. I am looking at (4) 140 watt 12 volt flex panels from Walmart that are 46.4" x 21.2". It would make for a tight fit Does this look like a possible/practical idea?

I have no experience with solar, so all my knowledge and insight comes from lurking on this site and YouTube. Any knowledge or experience you share with me will greatly appreciated.

https://www.walmart.com/ip/Elfeland-140W-12V-A-Class-Sunpower-Monocrystalline-Semi-Flexible-Solar-Panel-with-1m-MC4-Connector-Cable-For-RV-Boat-Car/417157223

[klpauba]

You might think about how you'll work in space for the wiring. You could easily get by with 3 panels unless you're carrying more than the 220 Ah batteries. You would then have to bridge the center seam -- something that the rigid panel made a little easier for me.

[rickst29]

Thank you both for your response. I have rough measurements of 46.5' x 86" on the back slide. I am looking at (4) 140 watt 12 volt flex panels from Walmart that are 46.4" x 21.2". It would make for a tight fit Does this look like a possible/practical idea?

I have no experience with solar, so all my knowledge and insight comes from lurking on this site and YouTube. Any knowledge or experience you share with me will greatly appreciated.

https://www.walmart.com/ip/Elfeland-140W-12V-A-Class-Sunpower-Monocrystalline-Semi-Flexible-Solar-Panel-with-1m-MC4-Connector-Cable-For-RV-Boat-Car/417157223
My TM is only a 2619, But, on the backside, your configuration needs to a avoid creating pressure and scratching on the chips, wiring, and back panel from having any part of the configuration "hidden" or "pressed" when closing the TM. The panels will probably fail mucht faster if they experience significant pressure, rubbing, and flexing in motion.

I'll SWAG that your 46" "free" is a shells-open measurement. If so, I'll recommend that you go back to the drawing board, and come up with another design.

[klpauba]

Pulled our TM out of the garage in preparation of a camping trip. The trip was moved back another month. Flex panels working well but there isn't much electrical load. The batteries are fully charged without the benefit of shore power for a few weeks now.

Hi, I bought a 2720 (2003) last year and have been considering installing flex panels on the roof. The flex panels have been receiving bad publicity lately and I wondered how yours are holding up. I prefer flex because of the weight and ease of install. I would be interested in your thoughts. Thanks Don

[BrucePerens]

Flex panels working well but there isn't much electrical load.

Good luck. I think UV damage to the front plastic will be the main failure mode. If these things were more reliable, I'd paper the roof of my TM with them. :-)

[klpauba]

Good luck. I think UV damage to the front plastic will be the main failure mode. If these things were more reliable, I'd paper the roof of my TM with them. :-)

Bruce seems to have called this correctly. The first panel I installed appears to have some UV damage that's causing the plastic to flake off. It hasn't yet affected the panel output that I can detect. I keep our TM in a garage most of the year and only expose it to the sun a few months during the summer so I'm surprised this happened so quickly.

I zoomed and cropped the image so it is a bit grainy.

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[Bill]

I noticed something in your picture that you may want to check out. The center panel (rigid glass) has a 9X4 array of cells (36 cells). This is common, and has reserve capacity to generate more current/voltage in a given level of sunlight. Each flex panel has an 8x4 array of cells (32 cells). This is less common, and is in general a sign of a less capable panel (i.e., less expensive). Since it puts out less voltage, these are sometimes called self-regulating panels, since their output decreases dramatically as the battery voltage rises.

While either panel configuration can be used in solar systems, I'm surprised that you can max and match the two. Let us know what, if anything, you find out.

Is the Voc spec different for the two kinds of panels?

Bill

[klpauba]

Hi Bill,

The rigid polycrystalline panel has a Voc=21.6V and the Isc=6.32A and the monocrystalline flex panels have a spec of Voc=21.7V and Isc=6.1A. It took a bit of work to find panels with closely matching specs.

[rickst29]

Is the Voc spec different for the two kinds of panels?
Bill
Primarily for other readers (because I know you to be an expert in these matters):

Kevin wired these panels in Series, so the Voltage values all "add together" with each additional panel (relative to TM and panel "grouding" Voltage). The output current is limited to the current of the lowest-current Panel.
In parallel wiring (more commonly used among TM owners), the output Voltage is equal to the voltage of the "weakest" panel - and the current amounts are added together.
- - -
Series wiring has an advantage: There is less power loss in wires by carrying far less current. But the Solar Controller and Panels must be able to handle the maximum disconnected Voltage of all the panels combined. In Kevin's case, that's about 64V. His Solar Controller can handle up to 150V, so there's no problem at the Controller (it's a good one).

The maximum "System Voltage of the individual panels is usually much higher (400-600V), and not a problem - unless the panels fail.

[Bill]

Kevin -Sounds like you did your homework. Good show!

And Rick - you are right about the series hookup. The problem I described is only relevant in a parallel hookup, since if there is much voltage difference, the voltage of the highest panel would tend to back-bias the lower panels, turning them off. With voltages as close as Kevin chose, it is not much of a problem.

There is a good article on 32-cell vs 36-cell panels at
http://www.alternative-energy-tutorials.com/energy-articles/how-many-solar-cells-do-i-need.html
It explains the "self-regulating" behavior I mentioned.

I am by no means a solar expert. But in an earlier life, I did spend several years on the discussion group at Northern Arizona Wind and Sun, one of the best solar sites I've run across. Learned a lot.

Thanks for the correction.

Bill

[TammyandTony]

Kevin,
I also have 2720SL and plan to follow your wiring method.
Starting with just 1 100W panel, possibly going to 2.

Wondering if you found anything you'd do differently after a few years of use.

[klpauba]

I'm pulling my TM out from storage tomorrow so I'll do a few solar performance tests to see how things are working.

The only thing I'm keeping in check is the deterioration of the surface of one of the panels that I suspect is from UV light. I hasn't yet shown any reduction in power produced, though.

[rickst29]

If the picture is showing separation and bubbling of the surface plastic (at rows 3-4 from the right end). I don't have that, even though one of my flex panels is a few years older than yours. But my panels are also much further from the roof edges than yours, and all on the front shell. See image at https://www.trailmanorowners.com/forum/attachment.php?attachmentid=18898&d=1586104272 for reference.

The front-most "side" of the front shell has the wind-control angle at the top, and that "side" (with the covered window in it) might be a bit more stable and strong than the 90% corner between the rear shell and its mostly vertical "back" side.

Maybe we made a mistake by installing on the rear shell, so close to the edges?
- - - -
If we were designing today, I would be inclined to recommend shingled panels instead. And with this negative experience, we'd go to the front shell.
- - - -
Aside: I agree with Bil that those specifications from an 8x4 panel are 'unexpected'; my small ones are 9x4 and my big one is 11x4. The rear-most portion of the 11x4 panel is actually NOT attached to the roof, because the diode and connector box is on the underside. It still shows no damage at all.

[klpauba]

I haven't yet collected any solar performance data (weather wasn't great last week). I did snap a photo of one of the two solar panels where the top layer is flaking away. The other flex panel (hidden behind the glass one) looks much as it did when I purchased it.
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This panel was purchased in March of 2016 on ebay and listed as a "Power Free" brand "Semi-Flexible Bendable 100w 100 Watt Lightweight Solar Panel 12v Battery OffGrid" and sold by AFP Power. One of the two originally bought were defective but I waited too long for it to be covered under warranty (I installed them in August of 2016).

The panel that still looks good is from Windy Nation purchased and installed in August of 2017.

[rickst29]

... and I'd witch to one of the modern "shingled" designs, in which the panels overlap each other (like roofing shingles) underneath a THICK layer of plastic.

WindyNation sells a good one, at $120, which is 42.3" x 20.5". I(mp) is 5.73A, a nearly perfect match for the other two panels in your setup. (Total rated power is 104 watts.) This one: https://www.ebay.com/itm/WindyNation-100-Watt-12V-Flexible-Monocrystalline-Solar-Panel-Battery-Charger/254698717740

I'd replace it now under nice weather, so that it's warm enough outside for the VHB stick to stick well. I'm sorry that the other one turned out to suck. :mad:

(BTW, Your private message mailbox is full, you need to delete some old ones.)

[klpauba]

I'll order one and install it after my first trip of the year next week.

I knew that the mailbox would get full soon, thanks for letting me know!