Mod #14: Solar Panel

Mod #14: Solar Panel

Submitted on: 06/18/08

     Category: electrical, green
Mod Rating: 12345

(17 ratings)

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Mod Description:

A solar panel converts sunlight into electricity. There. Now you know what a solar panel does. But it’s not that simple. Solar panel performance is just as dependent on sunlight as it is on the type and size you choose. So installing one (or more) on an RV takes careful consideration of your options if you want to get the best bang for the buck.

Mod Difficulty:

This mod starts by assessing your needs. Do you want to have a way to keep your batteries topped up while the RV is in storage without shore power? Do you “boondock” a lot and need a way to re-charge your batteries after heavy usage over a few days? Maybe you just don’t want to run your generator for hours on end just to get that last 10% of charge in to your batteries. Your total power requirements will determine what type of solar panel configuration and sizing you should install. You can be as simple or as elaborate as your pocket book can handle. But it’s all about managing your expectations in terms of power as a solar electric system can get very expensive if you want (or need) a lot of power.

An example of a simple configuration is one that just keeps the batteries topped up. There are many companies that will gladly sell you a small panel and state that it will recharge your batteries in no time and give you lots of extra power to run devices. Don’t be fooled by these claims. At a minimum, you will need at least a 15 watt panel just to keep up with the idle power consumption of the RV without any appliances or lights being used. The LP gas detector and the refrigerator circuit board normally draw a small amount of current and this is what runs the batteries down over time when not on shore power. A small panel can just keep up with this small power demand, but no more, and that’s in direct sunlight!

A more common configuration is to use a single 100 to 125 watt panel with a charge controller. A charge controller provides a way to ensure the solar panel cannot overcharge your batteries. It does this by switching the higher charging voltage from the panel to a lower float voltage when the batteries are fully charged. This ensures your batteries won’t be damaged by excessive voltage from the solar panel over time. Some charge controllers, like the MPPT (Maximum Power Point Tracking) type, can actually boost charging current as much as 20%. Get one of these if you are in a high latitude area or if you expect to have mostly less than sunny conditions.

100 watts of power can provide about 6 to 7 amps of DC power in direct sunlight. This is enough to provide some charge to the batteries while running a few lights, or the water pump occasionally. Anything more and you will have to add another panel. If your power consumption is higher than what the solar panel can produce, you will need an alternative way to recharge your batteries as they will eventually become discharged. Or, add another panel. Did I already mention that? You can see where going solar can add up in a hurry if you have higher power demands.

Larger power requirements need an array of solar panels and high-current charge controllers to keep up with demand. Many high-end class A and class C motorhomes have options for high power solar systems from the factory. These systems are typically sized for total power self-containment, meaning all demands on the DC RV electrical system can be met on solar power. These systems are very expensive and should be carefully considered against using a generator instead. If you just have to have the best, then go for it. The choice is yours.

TipWith any solar panel, maximum output is only achieved if the solar panel gets sunlight directly from overhead. Even partial shade or sunlight from an angle on any part of the panel or panels can diminish the power output greatly. Keep this in mind when looking for that shady spot to keep the RV cool. No sunlight, no solar power.

TipTo get the most out of your solar panel, position the panel (or RV) to face the south and tilt it perpendicular to the sun in the afternoon. This will ensure you get the most sunlight throughout the day and thus the most power output from your panel. Tilting mount kits are available to help with this.

ModMyRV recommends these parts for this mod:
SunForce 60 Watt Monocrystalline Solar Panel with 7 Amp Charge Controller (Pack of 3)
Go Power! 80 Watt Solar RV Kit
85 Watt 12 Volt Solar Panel - Ul Approved - Tl(rv)
Go Power! ARM-UNI Tilt Mount Kit

General Reference
RV Solar Electric Power Article
The Ultimate RV Electrical System

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25 Comments For This Mod

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  1. jmt

    This really seems like a lot of work and some serious $$$.

  2. cccale

    This is definitely on my list of mods to do. I almost got some 18w panels from Woot until i realized i need 200-300w. :(

  3. ModMyRV

    It is a lot of work and does cost a bit of money but it sure is convenient and helps to avoid having to use a generator for most things.

    Like cccale says, you need to ensure that you size your panels to your electrical usage. Otherwise, your batteries will not be happy.

  4. Bob Vaughn

    Is this a mod that must be installed and removed each an every time the RV is moved ? Now it seems like a needless expense because you would always have to park in the sun…I much prefer to park in the shade because it is cooler….

  5. ModMyRV

    Well…yes, you would have to park in at least some sun to get any benefit. Some have made portable solar panel stands that you would place in the sun and run the wiring back to your charge controller.

  6. mhotchkiss

    Two panels and charge controller total cost apx 200 $can. This will extend battery life and we never use our generator. (13 watt panels)

  7. Bart

    I only use my RV on the weekends at the lake and only move it twice a year. I did this mod and it works great. We use the batt on the weekend and it recharges during the week. I have one 80W panel.

  8. Glenn

    I did this mod.I’m an electrician,traded my labor for the used panels(2-80w&2-45w)Got a 20amp mppt comtroller on ebay for $120.I est. 8% loss of used panels for 14.21amps at 12v. I also can connect a 1200w power inverter to the always fully charged batteries to get 120v for coffee or micro..Now this cabover camper is fully self contained.

  9. Glenn

    I did this mod. I’m an electrician ,traded my labor for used panels (2-80w&245w).Got a 20amp mppt controler on ebay for $120 I est. 8% loss of used panels for 14.21amps @12v.I also can connect a 1200w power inverter to the always fully charged duel batteries for coffee or micro..Now my cabover camper is fully self-contained.

  10. Glenn

    My 20amp mppt solar controller has (+)(-)terms for load.My theroy
    is the load terms.are 12v from solar during sunlight with 12v backup from battery.I’d like to add a fuse block to this load for
    12v power to the fantastic fan and a refrig.cooling fan,which both
    operate in the heat of the day.Can anyone tell me if this idea will work?

  11. Portagie68

    Our needs must be simple. I just invested in a 45 Watt portable solar system. Jerry rigged it to work this time and went dry camping This met our basic needs during the 4 day dry camping vacation we have just come back from. I have a generator install on my trailer which I ran 5 times. Once to heat lunch, twice to make coffee mochas, once to run my back massager, and once to raise the trailer after I unhooked it(just to make sure the old gen would work after a long rest). Please notice I never ran the generator just to charge batteries. We have also done some mods in the trailer to save energy. I like shade, so considering wiring restriction and power location I am going to mount my charge controller on the light stand in the rear of our trailer, wire it to the 12 volts going to the power converter and add a plug to the rear of the trailer (right below the 110 volt hook up). By plugging a 15 ft 12 AWG (longest I can have by manufactures requirements) extension cord into the plug on my trailer the portable solar pannels are almost always in the sun. While I was home I found out that the two slides can be opened and close five times using only my battery and solar pannels. This is five times in less then 2 hours. I had some silde problems that needed addressing. Power drain from the battery was minimal. So next year, on our annual dry camp vacation, the old solar pannels will be plugged into the back of my trailer doing their thing while the generator will be used for the finer things in life.

  12. B3479W

    B3479W Dec.13 09
    I have used 2 15 watt panels on a 1998 Adventurer motor home to charge 2 6volt Golfcart batteries. This worked well for long weekends in the summer. I have just purchased another MH and Iam thinking about what type of System to use on this one.
    Does anyone know of a way to mount solar panels on a roof without making holes in the roof?

  13. ModMyRV

    I can’t think of any other way except to mount the panels to something that already is on the roof, like the AC cover. But you would have to reinforce the cover to hold both the weight of the panel and the additional air resistance caused by the panel being up in the air stream.

    As I think about it, I don’t really like that idea. How were your panels mounted on your Adventurer? I know a lot of people mount their panels to the roof using wall anchors and sealant.

  14. B3479W

    Sorry for taking so long to respond,
    I mounted my panels directly to the roof with 1 inch risers under
    them for air circulation. I sealed the screws with silicon sealer
    But I was never really comfortable with 4 holes in my roof. I did mount another panel on the air conditioner, but that was sort of unsitely. Everyone ask what is that on your a/c.

  15. ON-A-ROAD

    I’m going to do this mod soon. I already bought a Go Power charge regulator volt meter. About all we use our inverter for while dry camping is watching satellite TV. When we have to use our furnace for heat it really eats up battery life fast. (we have two 6 volt batteries). So I’m thinking a 50 or 80 watt panel will do the job for us. Once everything is all hooked up, and we are not using the RV, do you have to unplug the power cables from the panel?

  16. ModMyRV

    Nope. You can keep the solar panel plugged in all the time. The Go-Power charge controller will manage the power produced by the solar panel so it won’t overcharge your batteries.

  17. ON-A-ROAD

    What is the better solar panel to use on a RV. Mono or poly? If I read all the hype right, the poly is better for lower sun light. (like on cloudy days).

    There are a lot of good buys for both kinds right now. I hope to be able to get by with just a single 50 to 80 watt panel. I want to not have to run my genset so much on boondocking week ends. (two 6 volt batteries, and a Go Power 300 watt pure sine wave inverter, to run the satellite and TV when boondocking).

  18. builder

    I did this mod a year ago using a Sharp 80 watt panel. I quickly realized that with shading and cloudy days, it is rare to get full sunlight / 100% power output even in the summer. I do a lot of boondocking so I’ll add another panel this season. I regret having to use the generator in remote, natural sites.

  19. Toni Coppola

    We got our RV kit here…

  20. BackRoads

    If camping to you means ‘bringing it all with you’ then your going to need a generator or thousands of dollars of solar gear, batteries, and inverters.

    If camping means ‘getting away from it all’ then you can get by comfortably with a 135 watt panel, a good mppt controller, two deep cycle batteries, a small 400w inverter, and LED lighting throughout the RV (all for under a thousand dollars).

    I fall into the second category, and have boon-docked w/o using my generator (still take it for emergency backup and long overcast periods) for weeks at a time. Soooo peaceful!!!!

  21. USMC63

    Here I’d like to add my 2 cents worth as someone who has been doing it for sometime, and have had many disappointments. First, if possible….avoid pre made kits. They are for newcomers to the idea, and may not work for you. Do some research. It doesn’t have to be all installed at once. I personally have commenced adding a extra panel and battery. I started with mine 10 years ago.

    Avoid large inverters, anything above 600 watts will cost you plenty in the form of dollars, and wasted battery power. They draw current even when setting idle. It’s fine to go with them….in houses that can accomodate large solar systems. Keep in mind you’re in a RV of sorts.

    Do not fall for the hype of MPPT Charge Controllers. They’re the idea ticket for large systems, but you can’t install a large system on a RV. Also, I’ve had two, and the most increase I ever seen was in the neighborhood of 6% increase, and that was three times. If your installation is under 600 watts….you don’t need it. A PWM will do just fine. A MPPT works swell in the PWM bulk charge mode, after the bulk charge passes it becomes a PWM. That’s during idea conditions of 25°C, 77° Fah.

    Do not locate your charge controller at a distance from the batteries. It should be as close as possible, opposite wall or in another compartment, but close to the batteries. Never install a CC in the same area as the batteries. Distance will create great voltage drops with DC wiring, and that current the battery needs, otherwise it’s wasted in long wiring runs.

    Remember, you’re not dealing with AC from the panels to CC to batteries….it’s strictly DC, and wiring does make a differance. Never take the easy route of installing solar wiring, ie; thru thr the fridge vent. Yes, it’s easy, but the heat will also cause voltage drop, and never mount a CC there. Many RV installers are doing and suggesting this. They simply don’t know, or haven’t done enough dry camping/boondocking.

  22. kelownamikey

    Earlier this year I installed a 170 watt system (two 85 watt panels) on my roof. I used stainless screws to go into the aluminum studs and stainless expansion bolts elsewhere, but in each pre-drilled hole I used PL construction adhesive inside and then Dichor sealant LIBERALLY on the outside. I ran the wires down my fridge vent and installed my digital 30A charge controller beside my power panel, then wired it to the 12V input on the panel where the batteries connect. Even with all LED’s I use a lot of power day and night in my TT and my two 6V golf cart batteries are almost always at 100%. My whole system was $350 including all hardware, wiring, delivery and tax. All I had to purchase was the sealant. Best investment I have ever made for camping by FAR.
    After endless, mind-numbing research the company I bought from is Solar Energy DC out of Laval Quebec and I would definitely buy from them again. My only regret was not doing this sooner, as it was far cheaper and easier than I ever thought.

  23. dryflycaster

    In a comment by USMC63 (way back in 2012) I noticed that the commenter didn’t recommend mounting the Charge Controller inside of the battery box.

    What is the reasoning for this? Is it the safety issue of possible sparks near a battery or some other issue such as heat or the corrosive atmospheric conditions within the box that might harm
    the controller ?

    I plan to add solar to my camper (keeping the panels portable vice permanent mounting) and will be utilizing two 12V batteries in one fairly large hinged top battery box. By large I mean the box
    would probably hold four batteries vice the two I am planning to use at the present.

    I can easily add attach another vented waterproof box to the outside of the battery box, but it would be a much neater installation to install the controller inside the battery box.

  24. dlsacco

    Two 140 watt kyrocea panels and a Blue Sky 2512ixhv solar charge controller and IPN pro remote / shunt monitoring on the roof of my Hitchhiker II LS. Currently returns my 200 amp hour battery bank from overnight use in about 3 hours in the Denver sun

  25. Cracbean

    I just bought two 150 watt panels for my rv. Do they have to be disconnected from the batteries while plugged into shore power? My concern is with the regular charger that automatically charges the batteries and the panels together work work right or be too much for the batteries.

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