mounting panels on RV

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System
System Posts: 2,511 admin
in Solar Information links & sources, event announcements #1
I need to know if it is okay to mount solar panels flush/flat on top of my motor home? I am not physically able toclimb up and down or to store, carry & set up my panels.
Any suggestions would be appreciated.[/B]
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    Re: mounting panels on RV

    If you have "good mounts", mounting flush can be done...

    The issues:
    • Summer camping--not too much power loss. Winter in northern latitudes, can lose lots of power (sun low on horizon)
    • Panels flush against roof run hotter and with MPPT type charge controller, the lower Vmp will reduce panel output on a hot day.
    • Panels with a 5 degree or greater tilt, tend to be self cleaning. Flat mounted panels tend to need manual cleaning.
    • Tilting panels is a pain.
    Tells us when/where you plan on RV'ing (in what season) and we can run the PV Watts website to estimate power generation with tilted/flat mounting.

    Or you can run PV Watts yourself... Pick locations near your planned travel areas with similar weather (marine layer can kill summer production). Panel size, smallest is 1 kW (1,000 watts of panels--for yours, if less wattage, just multiply times the results... I.e., 250 watts of panels, multiply by 0.25, etc.). For derating, a good number for off grid is 0.52 (yes, 1/2 of panel rated energy is lost in real life). And you can then choose mounting type and tilt for your installation.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: mounting panels on RV

    I will be out mostly in May thru September. I will be in in the northwest in the months of June, July & August. In the Southwest through out the rest of the year.
    I am new to solar energy and have four 15 watt panels.
    Can anyone suggest mount types that would be good for this application. I would think that it would not be good to mount the panels directly onto the roof but to leave a space for cooling air flow under the panels?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Re: mounting panels on RV

    Our host sells RV mounts.

    My question is about your 3x 15 watt panels... Sounds like those may be Amorphous solar panels... Those panels tend to be about 1/2 as efficient as typical crystalline solar panels. Which means that you need about 2x the roof area for the same a mount of power if Amorphous panels are used.

    And then this back to how much energy you plan on using every day... And would the extra costs of a crystalline panels to replace your current 45 watt panels (if my guess is correct).
    "Station Identification"
    "City:","Seattle"
    "State:","Washington"
    "Lat (deg N):", 47.45
    "Long (deg W):", 122.30
    "Elev (m): ", 122
    "PV System Specifications"
    "DC Rating:"," 1.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 0.5 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 0.0"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 6.4 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    6, 6.06, 86, 5.50
    7, 6.19, 89, 5.70
    8, 4.97, 71, 4.54

    So, the above is for 1 kW (1,000 watts) of solar panels, mounted flat, for Seattle in June-August...

    Call it 80 kWH per month per 1,000 watts of panels for summer in Seattle:
    • 80,000 WH * 1/30 days per month * 0.045 kW of panels = 120 Watt*Hours per day of 120 VAC power
    • 120 WH per day / 12 volts = 10 AH per day
    For the rest of the year in Phoenix AZ:
    "Station Identification"
    "City:","Phoenix"
    "State:","Arizona"
    "Lat (deg N):", 33.43
    "Long (deg W):", 112.02
    "Elev (m): ", 339
    "PV System Specifications"
    "DC Rating:"," 1.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 0.5 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 0.0"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 8.5 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 3.26, 46, 3.91
    2, 4.31, 56, 4.76
    3, 5.52, 78, 6.63
    4, 7.21, 98, 8.33
    5, 8.12, 111, 9.44
    6, 8.28, 106, 9.01
    7, 7.79, 103, 8.76
    8, 7.17, 96, 8.16
    9, 6.21, 80, 6.80
    10, 4.97, 68, 5.78
    11, 3.65, 48, 4.08
    12, 2.92, 40, 3.40
    "Year", 5.79, 930, 79.05

    You can see that in December, you would got 1/2 (40 kWH vs 80 KWH for summer in Seattle).

    If the panels where tilted to face the sun in December (tilt them to ~39 degrees), you would get:
    "City:","Phoenix"
    "Array Tilt:"," 39.0"

    12, 5.08, 76, 6.46

    An average of 76 kWHrs in December--or almost as much as a flat mounted panel in Seattle during the summer.

    I would look at your loads--45 watts of solar panels of flat mounted panels is not a lot of power.

    Now, if you could justify/fit one or two 135 watt Kyocera solar panels--that would be really nice.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • soleil
    soleil Solar Expert Posts: 45 ✭
    #5
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    Re: mounting panels on RV
    llgillette@cableone.net wrote: »
    Can anyone suggest mount types that would be good for this application. I would think that it would not be good to mount the panels directly onto the roof but to leave a space for cooling air flow under the panels?
    I'm using these simple mounting feet that I bought from N Az Wind & Sun: http://www.solar-electric.com/unrvflmofefo.html
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  • Jim45D
    Jim45D Solar Expert Posts: 102 ✭✭
    #6
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    Re: mounting panels on RV

    Hi, I'm new here also, but not a beginner to solar mounted atop a RV. I did notice that you said you had 4@ 15 Watts, the moderator stipulated 3 panels. That will change things somewhat, but not enough to loose sleep over. At any rate that's 45 Watts compared to 60 Watts. It's still not enough! Unless all you want to do is keep a trickle charge to your batteries, and run a light or two for awhile. You need to determing what you want to use, and go from there. Personally, I use 4@ at present time, each being a Kyocera 80 watt. I still need another, just to feel good about it. I have the room. I also have the problem of not being physically able to run up and down on the ladder. However, I did mount mine on adjustable bars. If at all possible, obstain from a flush mount. If you must mount flush, then maintain at least a couple of inches between the panels and the roof. Summed up, I presently use 320 watts, 2@ Concorde Sun Extender batteries, and a tracker setup modified from a old satellite tracker TV dish. Getting ready to install a 25 amp Blue Sky controller. I use the 20 amp presently, a 2000 Heart inverter, and the link 1000 controller. It will do most of what I want to do now. TV, Microwave, Computer, Fans (2), I also went with the Turbo-Kool cooler. There's not enough room to run AC units on a RV with solar panels. So far , so good! I also live in Arizona, and would be happy to help if I can. I've had these panels installed now for over 9 years, and very little problems. Stay away from so-called deep cycle batteries, ie; Wal-Mart, Sam's Club, etc. They haven't a clue. I purchased mine, after a lot of crying from Az. Wind & Sun.....some 5 years ago. Still going strong.
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  • Jim45D
    Jim45D Solar Expert Posts: 102 ✭✭
    #7
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    Re: mounting panels on RV

    Look at post # 6 above. I will help you if I possibably can. Don't attempt to store, or carry around the panels. Mount them and be done with it. I have done some very unique mounting on my RV. It's a 33 Foot Apollo, and I utilized the ladder extender on the roof for mounting my panels. I do have photos if you're interested. I will check this forum daily to see where you stand. Incidently, I use a step ladder to access my RV ladder. I can't pull myself up the ladder from the ground. I used to be able to do it, but can't anymore.:blush:
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
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    Re: mounting panels on RV

    My gees is that you have a Harbor Freight or Northern tool panel(s).

    That 45 watts of panel is likely to deliver only aout 2 amps into 12vdc if you are lucky. These are suitable only. As a battery tender, not for providing any real power.

    For example, a typical RV will have a steady current draw of ~ 1/2 amp just sitting as battery relays are held open. Standby inverter load tend to run ~1 amp, so the daily load on that battery is likely to be ~ 18 ah, or ~215 WH/day.

    Your 15 watt panel, might me lucky to produce somewhere in the range of ~10 ah, so you are not going to be able to power any additional loas with this set up.

    Tony
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  • Jim45D
    Jim45D Solar Expert Posts: 102 ✭✭
    #9
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    Re: mounting panels on RV

    Good evening Mr. LL Gillette. I did as I said. I checked back earlier this afternoon, and I'm now here again. Are you monitoring this forum? Perhaps you've decided to leave Page, and head for Seattle. I'm still available to offer any imput I possibably can. I'm no expert, just experienced with constant use of my system. I'm a fulltimer Rv'er....if you're not familiar with this phrase, it means that I live it, in it, 24x7, and have for going on 15 years. There's a lot of changes I need to make, but as usual the eagle hasn't landed here ......yet! I will continue to monitor this forum, and just mabey I can help. I knew nothing at all about solar except what I'd read, and then still couldn't figure a lot of it out. I had my wiring , inverter, monitor, etc; installed by a Engineer from Palo Verde Electrical Transmission Plant, located in Tonopah, Az. I think he did a great job. I had him go by the book concerning all my connections, etc, etc. I did the panel wiring myself, and the adjustable/tilt settings. I only do it twice per year. Let me know if you're interested. I still have plenty of questions myself for a experienced moderator. Keep in touch.
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  • bluewickedburner
    bluewickedburner Solar Expert Posts: 78 ✭✭✭✭
    #10
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    Re: mounting panels on RV
    llgillette@cableone.net wrote: »
    I need to know if it is okay to mount solar panels flush/flat on top of my motor home? I am not physically able toclimb up and down or to store, carry & set up my panels.
    Any suggestions would be appreciated.[/B]

    I'll try to answer your question directly. I'm new to solar to but not mounting systems. It is not advisable to mount anything that can crack or warp directly to something that can shift or bend, and the roof of an RV will do all of that. For that reason, use some type of mount between the panels and the roof. There are many different types from those that keep the panel parallel to the roof to those that have rocker arms that tilt and some that even move the panels to track the sun.

    The panels are fastened to the mounts (whatever that may be) and the mounts in turn are fastened to the roof. There again there are several ways to attach the mounts to the roof but in almost all cases the panels connect to the mounts with screws of clamps.

    Another reason not to mount panels flush and flat is that you should allow for some air to flow around and underneath the panel for cooling but I'd be more concerned with being able to clean under the panel since things can get caught underneath them and bugs will always find the smallest of places to hide in and do damage.

    If you must mount the panel flush and flat which is what you are thinking about, make sure that you don't just lay the panel on the roof and then mount it that way. Use a flexible seal so that the panel is just above the roof itself and when the roof shifts or sways the panel isn't rigidly attached, it can sort of float.

    When it comes to the things mentioned by others such as tilting, panel sizing and the types of panels to use, I'll defer to them. Price doesn't always equal quality and it is important to talk to a good dealer that you can rely on for straight talk and one who will be there when you need phone support. Arizona Sun and Wind Power, the host of this forum are good folks and will give you lots of good options without selling you something you don't need.

    Mounting on a fiberglass roof vs a rubber covered one will allow different mounting options for each.

    Just try to remember that anytime you want to mount something rigid onto something that can shift or bend in any way that there should be a mount in between that allows the rigid material to stay that way.
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