I have to move our coach this week and may not have access to AC power for a while. I've searched and read a number of posts about various solar charger rigs that have been tried over the years. There seems to be a preference by our forum for something in the neighborhood of 100w. What's current thought on this (excuse the pun)?
I have a Trik-L-Start installed at the isolater and it keeps the chassis batteries charged from the house batteries. Would it make sense to put something like a 100w panel on the roof (will be in the open, no shade) and connect it to the house batteries and let the Trik-L-Start continue to tend the chassis batteries?
I do 180 and it covers both most of the time. I would do a pair of 150s and a good MPPT controller.
12V panels can keep your controller cost down and 135-150 W panels aren't too hard to find.
Trik-L-Start is a good idea but I just run a double male cord from one lighter socket to the other up on the dash. While on shore power, a 2 amp trickle charger keeps both sets of batteries (engine conventional, house AGM) at 13.5 volts, just about exactly what the manufacturer recommends. A 100 watt panel with an inexpensive MPPT controller will be more than enough to keep your batteries up while you are away from shore power. That would even be enough power to keep your fridge on propane and supply the 12V to the board.
Pierce
I ran a 100w to a Morningstar 6a controller at the foot of the bed. $20 bucks or so on sale for chassis. John H has described his run and I did pretty much the same. It is very easy to install aft from roof into the engine compartment. Much easier than anywhere foreword for us. For what you describe you don't need MPPT unless you plan on expanding your array. We do use MPPT for the 800w going to house. Love Pierces solution male/male.
A $50 100 watt panel and a $20 pwm 10 amp controller will do it, If you do not want it permanent, put panel on roof and run wires down ladder into engine compartment to isolator. Remember to shut off your inverter, it will draw a good amount even with nothing on.
Thanks everyone for the guidance. Ordered a small MPPT controller and a 150w panel.
Appreciate your help.
Yes, we store our coach outside with no electric service and our roof solar keeps house battery charged, and our Trik L Start keeps our start battery charged. Solar charge controllers should be set for correct battery charge voltage.
I'll be sure to pay attention to the voltage during configuration.
Thanks!
I have bought tons of stuff from these guys for other customers. Great prices, great products, really good service:
Windy Nation (https://www.windynation.com/)
Go big on the controller, they are cheap as chips. Then you can add more later. They are 18 volt panels.
I have still not discovered where my 3 siemens M65 solar panel wires terminate, or whether they still work (installed pre 1995). Is it true one dead cell will disable a whole panel? I assume they are trash.
When I started putting a single panel on the roofs of my Foretravel coaches in 1986 I ran the wire down the refer vent and tied into the 12 volt system at the power junction on the back of the refer.
43 watt panels. Between the three you should have 8 amps or so.
Got tired of dead display coaches back then. No way to plug all of them in at our lots.
As I reported yesterday in the "what you did today" thread, I have the solar charger temp'ed in (still have to permanently mount it on the roof -- right now it's just lying there in a secure spot).
As of yesterday evening it hadn't hit float status. I went by this afternoon (a partly cloudy, partly rainy day here) and the house batteries are now at float status, and the Trik-L-Start to chassis batteries is showing fully charged. That's with the refrigerator, salesman switch and inverter off, and the air leveling system and normal, non-switched, parasitic loads on. HWH compressor was slightly warm to the touch so it's running every once in awhile.
Charging path is 150w panel-->Victron MPPT controller --> house batteries --> LSL Trik-L-Start --> chassis batteries
Ran the 10ga wires from the panel down through refrigerator vent.
I'm stoked. It's my first "toe in the water" with solar and nice to have a small success. Thank y'all for the help.
Congrats on that toe. Not sure which Victron you chose but that is an excellent point of departure if you expand.
Lots of info about solar on UTube. Harbor Freight has good reviews on their recent add to solar and seems to be reasonably priced.
For mounting the panel, I suggest using stainless steel brackets "glued" to the roof. Ours have been up there for 2 years now, and just as secure as the day they were installed. Big plus: no screw holes in the roof, and you can tilt the panel (for optimum sun angle, or for cleaning under them) using simple prop rods.
What Chuck says. AMSOLAR sells the mounting brackets, a little pricey but well worth it.
You may have a structural failure with only four glued attach points. (AKA: Flying solar panels).
Prior to using glue on only four points. I would recommend a worse-case structural analysis be performed of 100MPH winds blowing across the panels. Based on my crude internet-search-based analysis for my 79x39 inch solar panels, which are attached to my U270 roof with fifteen pieces 2 inch by 2 inch 3M VHB (Very High Bond) tape, here are the results as my feeble memory recalls:
1600 pounds of VHB tape pull-out bond strength, per 3M specifications
800 pounds of pulling force due to a 100MPH wind
During a hurricane, the solar panels could act like wings and generate a lot of upward lift.
Of course, no one has done a hurricane analysis of RV solar panel structures, but I reviewed internet analysis of sticks and bricks buildings and their roof-mounted solar panels.
Here is a photo of my solar panels with 15 VHB tape attach points. One issue related to my prior post is that over time, the adhesive bond force may weaken, so I recommend designing 2X the required bond strength. If you loose 50% of the bond strength in 10 years, there is still a decent margin of structural integrity to withstand a 100MPH wind.
Speaking of 100MPH wind. Picture yourself driving down the road into a 30MPH headwind. So, we may experience hurricane-force winds more frequently that originally thought.
What adhesive did you use?
I like VHB a lot and we used it extensively where I worked. However the PO had FOT coat the entire area of my coach's roof with a product that both seals and provides a non-skid surface. The finish has thousands of little wart-like bumps. Because it's not a smooth surface I think I'll need an adhesive that's more liquid in consistency so the bracket is fully bonded to the irregular surface of the roof.
To Tim:
Your concern for the structural integrity of my solar panels is understandable, and taken in the helpful spirit that I am sure it is given. I'm a English major, so I don't know nuttin about "worse-case structural analysis". What I DO know is that my panels were installed by AM Solar in Springfield, OR. I went to them because I wanted my installation done right. They have done hundreds of panel installs, on all kinds of roof surfaces, using the "4 stuck-on brackets" method. They claim to have never had one single panel come loose, and I believe them. They have a VERY loyal online following of happy, satisfied customers.
We have driven thousands of miles since our install, and sometimes into very strong headwinds. I am sure you could propose a scenario in which the panels could be ripped off, but apparently we haven't encountered it (YET). As to how strong the glue will be in 10 years, I don't know, but AM Solar has been using this method for quite a while so I guess it's holding up OK.
In the end, you have to do what you think is right, proper, and adequate to the situation. Glued on brackets is only one way to install solar panels. Several forum members have bolted/screwed down their panels, and are happy with that method. Your method sounds fine, also!
As always, the best rule is: Do What Makes You Happy!
To Mark:
I don't know exactly what product AM Solar used to glue down my brackets. I have been asked that many times, and I was negligent in not getting that info when they were working on our coach. The guys at their shop are extremely friendly and helpful to "do it yourself" customers. I am sure if you called them, they would be happy to answer any questions you might have. They would also be happy to sell you some stuff, if you like their offerings!
They also have a nice website with lots of good info. Here is their discussion on the subject of panel mounts:
Mounts (http://amsolar.com/diy-rv-solar-instructions/edmounts/)
Chuck, reading their info on the link, it looks like they put 3M tape under your brackets then sealed with the glue to keep the weather out.
That would also be my guess, but I hate to state as absolute fact without knowing for sure. I do have the Dicor on top of the mounts.
Having 540 watts put on roof at AM Solar as I type. 3M High Bond Tape, Dicor on top of brackets.
Whats wrong with screwing the panels down? You already have over one hundred holes in the roof for antennas, AC, vents, etc and with any kind of skill, the holes can be easily sealed. You can screw directly into the aluminum roof members or using a variety of fasteners, screw into the 0.400 inch thick roof (fiberglass plus wood). I used 6 fasteners per large panel and they have been great. Commercial solar shops also do a lot of screw down installations.
Pierce
AM solar supplies the 3M tape in their kits as well as the dicor. I mounted ours last year and they show no movement or stress on the mount. They also supply the stainless fasteners if you don't trust the tape. I was going to use them on the leading edge if there was movement. Glad I did not but if you are worried use Johns Hs method of leading edges.
George,
Am I correct in assuming the 3M tape is to secure the brackets to the roof, and the dicor is to cover the metal brackets so they look more "roofish?"
Since you are not drilling through the roof at the brackets, is there any reason besides appearance/ aesthetics to use the dicor?
Thanks,
Trent
Very interested in the wiring runs they use. I may well be self installing their products this fall. Are your batteries in the center of the coach like mine are in the 2003?
If you are able to describe the runs they use roof to controller to batteries it would be very helpful. What products have you chosen from their product lines?
On my previous 94 Bluebird BMC 37', I self installed their products with 300 watts of panels.
Hi Trent,
The use of the dicor in my opinion does two things. First it supplies additional adhesive. Second it protects the foot adhesive from the elements. UV, water freezing and thawing, etc. Perhaps belt and suspenders but cheap peace of mind.
AC7880, I am not sure of your other components but if they will need upgrading in the near future, you have the opportunity to upgrade to an all Victron system. Several others on the forum have now moved in that direction. What it can give you is a fully integrated system that does not have to be monitored for charging conflicts etc. and provides top notch monitoring of your system as a whole. One other note. Buy a controller that you can expand with in the future. If you are going to put up 5-600w buy a controller that can take you to 1k+.
They are pricey but the support I received balanced it out. You may want to give Mitchell a call at AM. Very service oriented and nice to work with on your project. I was never talked down to or had him lose patience with my entry level knowledge.
Chuck,
Thanks for the link. As you say, lots of good information on their site!
Mark
Chuck - that's a sharp looking installation!
Here a photo of our roof surface. Not sure if the detail will be adequate after upload to see the non-slip bumps. Sorta like the surface of an orange or orange-peel drywall texture.
In the case of our coach, the roof was (and is) still the original gelcoat. I cleaned the roof pretty well before I arrived for our appointment. When they are working in the shop they have a 2nd story window in the office area where you can observe the activity on the top of your coach. I could see that they used some type of cleaning agent to prepare the surface before sticking down the brackets, but don't know the specific product.
My concern with any kind of "aftermarket" roof coating would be "How well does it stick to the original gelcoat?". If you stick the bracket to the coating with tape, and then the coating comes loose from the gelcoat, then that would not be desirable. If you are not sure about the strength of the coating bond to the roof surface, then that might be a good reason to use a more mechanical means of securing the brackets, like the screws championed by Pierce. AM Solar uses the screws with rubber roofs for the same reason.
I like to avoid drilling holes
anywhere on our coach, if I can find another way to accomplish the task. But that's just me!
Photo below of AM Solar crew performing surgery on our coach. First class operation all the way! (PV System, Installation, at AM Solar (http://www.foreforums.com/index.php?topic=26206))
I also read on AM Solar's site about their using screws on rubber membrane roofs. I agree with the parallel you draw and agree that holes in any roof are best avoided if one has alternatives; however, in this case I think I'll go with screws. Probably will use 3M 5200 in the screw holes and a generous application of 5200 between the brackets and roof surface to ensure the orange peel is filled and fully bonded to the bracket. After that cures, I plan to mimic your installation and coat the bracket base with Dicor.
How often do you go on the roof and tilt your panels? Is the decision to tilt or not tilt predicated by your length of stay? I'm 65 and have noticed a very slight change in my balance ability. Not enough that I'm worried but enough that I'm more thoughtful about being careful. That's led me to the idea that perhaps it's wise to install more panels mounted flat than fewer with the tilt feature. If one loses, say, 20% production from a non-tilted installation, then I can add enough panels to make up the loss from not tilting.
I'm not criticizing your installation. Not at all. It's a beautiful install. I'm just saying that in my case it seems to make sense to reduce my risk by only going on the roof when absolutely necessary. One hospital trip would pay for a lot of equipment.
When AM Solar does the install, the tilting "feature" is simply a side benefit of their mounting system. If you think you might ever want to tilt the panels, they offer you the option of buying the "extra cost" prop rods. If you will
never want to tilt the panels, then you don't need the rods and you save a few bucks. Truthfully, I have only tilted our panels for better sun angle one time in two years - that was last January at Q. Unless we are planning to be camped in one spot for a week or more, I wouldn't bother. It
does require some time and physical effort to get the panels raised up in the tilted position...how much would be directly proportional to the number of panels.
At 72.5 years of age, I am fortunate to still be fairly well balanced (physically speaking, that is...). I can scamper up and down the ladder to our roof like a monkey. I HAVE found the tilting feature to be handy for cleaning the roof. A lot of dirt and trash accumulates under the panels, more so since our coach is parked outside 100% of the time. Getting the panels up out of the way makes scrubbing the roof much easier (but not any more enjoyable).
Mark,
I have panels on the roof that sit flat and thought about changing brackets/mounts so they can be tilted. But have the same concerns about getting up there as you are.
How about some liner 12V motors remote or push button? I do not think it would be that expensive and perhaps install two per panel or fabricated that you can tilt either way depending or sun. I bet someone has already done it.
Charlie
!
That would be a fun project, wouldn't it?
Something like this:
12 Volt 2" inch Linear Actuator W/ Wireless Remote Control Controller for... (http://www.ebay.com/itm/12-Volt-2-inch-Linear-Actuator-W-Wireless-Remote-Control-Controller-for-Car-RV/272308355857?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D45701%26meid%3Dcb3b3e2372d948e9ae07bce7e8bf4450%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D282172653280&_trksid=p2047675.c100005.m1851)
Motorized tilting is available - search on YouTube for videos. In most cases, not practical or cost efficient. Like Mark says, if you don't want to tilt, just add another panel to make up for the 20% loss in efficiency from flat mounting.
Mark I agree on flat mounts. I think you will find that adding panels will offset the gain. In our case, the input is throttled down before you reach anything close to midday. We designed ours originally for 500+ based on our two previous installs. We installed 800 or five 160s from AM. It also adds to production on partly cloudy and cloudy days. I have posted the screenshots before but they are probably in other threads. Here is a day close to the equinox in Arizona and midsummer day in the Outer Banks solar I did for a friend. The last 8 months have been atypical for us and the Banks shot is how we usually camp. These are GMT times. The spike you see is morning coffee and the dead spots are the jet pack downtime.
The Banks usage is with the Uline on testing for residential fridge. The highest spike we recorded to date was just over 700w but normal highs are in the 600s. We won't see the high usually because they have been throttled by solar noon.
Smart! Humpty Dumpty can only climb up so many times before...
Just add a panel if you feel you need more. No need to make things more complex than they already are. Our panels are flat but more than we ever need. With all the new TVs, lighting, etc, our coaches consume much less juice than when the left the factory.
Pierce
George,
Love all the data. What Victron product gathers the data and what product do you use to read the data?
When I installed the new 40" LED TV, I was so surprised to see the yellow, government-mandated energy sticker say it would only take $12 to run it all year. It produces almost no heat.
I have tilted ours quite a few times and yes it is a bit awkward leaning over them and I seem to be older than others quoted. Not sure if I can do it for a while after falling off a ladder 3 months ago though, still very sore but that's another thing.
AM Solar does a good job and as G &S have said will give you all the info/ help you need even if not buying from them.
I have been there 3 times buying "stuff" and they did the first install that I have added too and upgraded the wiring runs to controller etc by going to '1 and #2 sizes.
5 yrs now and NO movement of brackets on roof with 3M.
900 watts and serves us fine as we do not plug in or go to RV parks, but are very concious of use of power.
JohnH
Mark,
I use the 702 battery monitor, the 100/50 MPPT and a Victron Multipass 3000. These all feed to the CCGX which is wifi or Bluetooth capable. I have a post with links to all of it with costs etc but can't get to it right now. Will post it later sorry.
I think I found it, George. Solar system upgrade overview (http://www.foreforums.com/index.php?topic=30035.msg257538#msg257538)
That's it Mark. Keep in mind I was a complete novice when I set out so you may spot an issue or two that you would do differently. Hope you find it interesting.
I have been spending my time recently learning fuel systems and reworking the engine compartment and your posts and questions have been very helpful.
I am sure that glue works, as many have done it. I also think that glue is easier and maybe quicker as no one has to look for roof structure beams. Also glue must be better if to gelcoat. It sure seems to me that on a painted roof, smooth or bumpy, the glue is only sticking to the top of a thin painted surface that is really not bonded to roof. But then one could scrape away the paint under the mount and attempt to glue to original gelcoat.
But for our coach, we are not concerned about screws into roof as each one is coated with silicone. I know others like 'better' sealant which is fine. We screwed down our Winegard sat antenna, storage pod, shower cover, roof antenna ground plane, so screws should not be considered never to be used.
Tilted panels are sails to a wind storm and it seems that if wind is too high, one may be tempted to lower glued panels.
We use long aluminum angles bolted to solar panels OEM mounting holes, no new holes drilled in solar panels.
Then we use long aluminum angles screwed to roof structures, which are located with electronic stud finder.
Then both long aluminum angles are bolted together, with some locations using nutserts.
This is our way for over 20 years and when we painted our coach, we removed all panels, had Rance fiberglass existing holes and located panels differently after painting. We have three 10' rows of aluminum angles holding 6 panels, each panel wired to a roof mounted combiner box.
Mark,
Don't over complicate things too much. Our 900 watts @24 volts on the roof have put out as much as 710 watts (50 amps at 13.8 volts into storage) but that is not typical. We have put over 5KW in a single day into storage but a realistic daily average is closer to 2 KW. We are in a high level of tree coverage now and are less than that but still more than the refrigerator uses.
Figure out what your needs are and then size everything accordingly figuring on maybe 25% overall, year around efficiency.
I never even considered any tilting mechanism, powered or manual. I am not getting on the roof to tilt manual ones (too much risk) and motors and wiring and controls seem way too complex and costly for this application.
My 300 watt panels have 12" long mounts, one at each corner on the side held in place with 3M VHB tape, 1.5"x12", no screws. I had the mounts made with an appropriate angle to match the roof curve. They are sealed with 3M 4000UV adhesive sealant. 72 sq inches of tape x 91 psi in tension gives me over 6500 lbs of holding power per panel. I cleaned the roof and brackets with acetone, then denatured alcohol and then used a 3M cleaner and adhesion enhancer and then stuck things together. It is rock solid.
Lots of help from Alan at Bay Marine Supply on sizing, Victron components, fuses, switches and the rest of the parts you need.
The single 150w solar panel has been working but just lying on the roof for about a month. As you may recall from above, our coach's roof has a textured, non-slip surface. Yesterday, to achieve a greater contact surface area I removed the texture from four areas on the roof and attached the panel using brackets and VHB.
Thanks again for all the ideas, photos and advice!