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Going Solar Powered On The Rv


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I'm on my way of installing solar panels on the RV. These are not going to be roof mounted but free standing. MoparMom and I figure you could just fold up the panels and lay them on the bed while travelling.

 

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Right now I'm doing a bit of bench testing and so far I'm very pleased with the 45 watts worth of solar panels. This solar panel kit is from "Harbor Freight" for $139 buck on sale. Then while I was there I picked up a 1200 watt inverter for 120 VAC power. Figuring against typical Amp hours of deep cycle batteries I figure 1200 watts is more than enough.

 

10 Amps x 120 Volts AC = 1200 Watts = 12 Volts DC x 100 Amps

 

Then figuring common RV deep cycle batteries are roughly 100 Amp hours then you have two batteries so that would give you roughly 2 hours of full 1.2kw power in theory. But we know you can't run a battery totally dead nor will a inverter operate below about 10.5 volts.

 

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My buddy has a cheap solar panel on his camper. It definitely helps on week long hunting trips. But you'll still need to be conservative with power or have a generator for periodic top off of batteries.

$139 for that big 3 panel solar system? Includes the power management unit pictures?

Edited by joecool911
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I had this same set up.  Used once & sold it.  WHY?  My trailer has 3 group 24 RV/Marine wet cells for DC power.  The solar worked pretty well...  but I was not set up to charge my big mobility scooter from the solar.  The mobility scooter runs on 24 volts...  and needs to be charged when not in use...   Our RV use is at primitive encampments...  where we must park on the outskirts (parking lot).  I have the scooter hidden in (primitive) camp during the daylight hours...  I thought about using the inverter to charge but the scooter's OEM charger is a slow overnight type charger.  My best option was to charge from the small generator 110v every 2-3 mornings from 7-10AM.  Charging the RV was incidental to charging the scooter so I opted to de-clutter my set up & sold the panels. 

Since we are in primitive camp most of the time...  we ran the refrigerator (controls), furnace some nights, hot water, a few lights.  The fridge was the main deal.    
     

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They are currently on sale if you have a coupon. (For some reason I think I goofed on the price there... :think: )

http://www.harborfreight.com/solar-panel-kit-45-watt-68751.html

 

Here is the inverter I also had a 25% off coupon for it.

http://www.harborfreight.com/1200-watt-continuous2400-watt-peak-power-inverter-69659-8890.html

 

As for us we just need a small amount of power but at night using the lights in the RV tend to drain the batteries and the furnace too. So by morning your firing up a generator. But it would be nice to just have the solar charging the batteries up through the day and not have to fire up the generator. Unless needing some serious power.

 

I like to camp out in the woods away from RV parks or campgrounds.

 

What I'm aiming for is to have all my controllers and inverter in the same cabinet with the master fuse panels and such. Then when I need a bit of 120 power I'll have a inverter I can flip on and plug in a short cord to power up stuff. Like its kind of nice to bring along the small TV and DVD player and sit back watch a movie.

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Not a bad price, but I am not sure you will get what you want out of them. They can put about 3.75 amps peak into the batteries, meaning it would take about 16 hours to bring them up from 70% (assuming 100ah group 27s). With the panal being moveable you will get a longer charging day, which will help.

On a cool night we get to 60% with just the furnace, our lights are all led. I have 2 group 24's rated at ~85ah (for now, a pair of 300ah 6's are going in).

I looked into solar 2 years ago and the cost was just too great for enough charging power to rule out a generator.

I have a 10w panel and it does allow me to run the stereo without draining the batteries during the middle of the day, but even a battery charger on a 100w inverter makes a big drop. 45w would be nice in the summer, when the furnace isn't used.

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Same thing here at home my solar is only 10x bigger from 45w to 400w worth of solar power and 810amp/hours of batteries. I still got the little 2kw genny for charging up for times I need more juice. Like here I've got a 6.5kw genny for the house. I'm used to living off 4kw worth of power.

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Mike, hope this isn't hijacking your thread too much...  If so split it off into another thread...   Another forum I'm on...  deals with Powerchairs, Scooters & such mobility devises.  (Give credit where due:  http://www.wheelchairdriver.com/board/  )   So rather than use the slow, overnight "dumb" charger with 110V input....  there are high tech "hobby chargers" which can be programed to fast charge vitually any battery...LI, LiPO4, SLA, RV, Truck/auto.   To do this I'd need to rewire the scooter & install plugs...  and build matching cord for the smart charger.  The smart charger can power off 12VDC directly. 

This would allow me to fast charge off the RV battery bank & charge the RV at different times...  including solar though I don't think I want the extra baggage for my purposes.          

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  • 3 weeks later...

I'm subcribing because I too am going to be investing in some "portable" solar here soon.  But in saying that, I have realized that I have a TON to learn about this stuff.  Its certainly anything but straight forward and is seemingly easy to get what you "think" will do what you're wanting but only to find out that its not. 

After talking to some people on forums, I've come to the conclusion that 200 watt panels are what I would be happy with.  With the ability to place them in the sun light while the trailer is parked in the shade.  200 watts should be able to keep my two house batteries happy so that we can get through the night comfortably without waking up to a couple drained batteries.  I do have a 5500 watt gen but its really only good for running the A/C or micro or watching some TV because even running it for hours doesnt offer enough charging to do much battery replentishing.

For simplicity reasons I've looked at kit's like this one: http://www.amazon.com/Instapark-PowerBox-Fold-n-Go-Solar-powered-Controller/dp/B007VWW8X2/ref=sr_1_17?ie=UTF8&qid=1393012065&sr=8-17&keywords=portable+solar+panel or http://www.amazon.com/Grape-Solar-GS-200-KIT-200-Watt-Off-Grid/dp/B009ANH7FO/ref=sr_1_15?ie=UTF8&qid=1393012923&sr=8-15&keywords=200+portable+solar+panel or http://www.amazon.com/200W-Mono-Starter-Kit-Controller/dp/B00BCRG22A/ref=sr_1_4?ie=UTF8&qid=1393013063&sr=8-4&keywords=200+watt+solar+panel+kit

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  • 2 weeks later...
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Well I got a break in the rain showers here and got a good start on the solar project. First I had to re-organize the power cabinet to fit everything. Here is before...

 

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Then now after moving both DC fuse panel and the AC breaker box and converter box to the back wall.

 

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Then I managed to get the solar controller hooked up and the solar lead ran outside. Even getting a good charge when the sun peeked out.

 

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I've got my 6 AWG wire ran through the floor but I need to head to town and pick up some EMT tubing and run it down the frame rail so the wire is protected. Also got to pick up the proper sized lugs for the inverter. So this is a small stab at the project and now it back to raining again.

 

As for the solar controller I used the factory wiring for it and routed it through the floor and outside. As for hooking up the solar controller I used some 16 AWG wire and had a unused fuse socket in the RV panel so I used it for hook-up. As for the max current flow from these panels is 3.2 Amps DC @ 14 Volt DC which is 45 Watts.

 

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I went back out later on and turn on the furnace and kicked back in the RV as it ran. Cleaning up some of my debris and trash from the project. I left the cabinet open to watch the voltage and reaction. So I set the heat for 65*F and it was 60*F inside already so it ran for about 10-15 minutes and dropped to about 11.8 volts show both on the gauge and solar controller. It was overcast out and not direct sunlight. Once the furnace completed its cycle it pop back up to 12.2 volts. I continued to fiddle around in the RV cleaning up stuff and within a short while it was up to 12.5 volts. I left and came back up to the house about hour later even being overcast out it finally reached 12.6 volts again. It's not a perfect system that recovers instantly (which would require more panels) but it does charge back up the batteries in a fair amount of time.

 

I'm wanting to redo the master bus lines for the RV original wiring and then add my inverter bus lead in too. So MoparMom is wanting to go to McCall, ID tomorrow so I'll be able to get my EMT tubing and miscellaneous stuff to finish the project.

 

So the stats will be.

 

3 Solar Panels @ 15 Watts a piece with a total of 45 Watts of power @ 14 volts and 3.2 Amps DC.

 

1,200 Watt Inverter (100 Amp DC load @ 12 Volts) with a surge rating of 2,400 Watts (200 Amp load @ 12 Volts)

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  • Moderator

It sounds like you need the bigger wiring from the batteries to the 12V distro panal hooked up, that's quite the voltage drop for 60 deg outside. What size wire is in there now?

My old setup (25' of 8ga and 170 AH) would drop from 12.7 to 11.8-12.2 with the heater depending on ambient temp and run time. I haven't played with the new one much but it so far hasn't dropped below 12.75 from 12.95 (3' of 6ga min and 300 AH).

My heater draws about 7.5-8A while running, for reference, so for every 10 min of operation you would need 23-25 min of direct sunlight.

What size/group/quantity battery do you have now?

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Down to the last bit of wiring. I ran my 6 AWG in 1/2" plastic conduit pipe. It worked out awesome because there was just enough give in the underside matting to slip a 1/2" conduit right across the tops of the ribs.

 

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The stuffed my 6 AWG wire from inverter to the batteries up front. All connections where soldered for the best connection possible. Even in the background I re-done the bridge leads between the batteries with fresh 6 AWG lead. I left the inverter lead disconnected for the time being till I get my 100 amp fuse from NAPA on Monday.

 

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This is now my second day of solar power on the RV. I know the battery voltage is low and not as high because I was load testing the inverter with everything from TV set, to a small heater to get a feel for how much power there is.

 

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A bit better view of the solar panels. Reason I opted for smaller panels and not mounting them on the RV is them I can park the RV in the shade and the place my solar panels in the sun. Enjoy a nice cool spot in the RV and panels will charge all day long. But if the panels where mounted to the roof then the RV would have to parked in the sun for good power collection. Now since the panels are free standing I had to have a set of panel I could store in the RV. So now size and weight became a factor.

 

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My last small project is to make a cord can under the RV so I can roll up my solar cord and stuff in back in a tube. More or less take a piece of 3" ABS sewer pipe cap one end and the put a clean out on the other end. Do a bit of magic in routing your cord into the can and mounting and your set. That's another day.

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Don't know if this will help anyone, but this link has some good info for anyone wanting to know more about solar and some of the short comings of some of the equipment out there. The guy who posted the info spent a lot of time/effort sorting through the what/how and has put together a pretty helpful read. It's about the most up front and objective discription of solar power I've come across so far.

http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

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I read thru most of it. Good info, and goes to show why I do my wiring myself. It's amazing what wire size does on both the charging and using side of things.

 

It's also very important to check with your battery manufacturer on charging specs, mine are not what he recommends.

I am not currently in the solar mode, but based on that article it would be nice... But I already own the generator(s).....

What I did find interesting was his comment on UL watt ratings. I would have presumed that they were closer. My TV is rated at 125w so we will see soon enough.

I did the math on my electric tea kettle. It was drawing 128A DC at 11.65V of DC power, that's 1491W of DC power, which works out to about 1340W of AC output at the advertised 90% efficiency. So either the inverter is much more efficient, or the heating element isn't 1500W.

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Like with my setup I found my long run of cable plus the size is limiting me a bit. I do have the inverter but can't quite get the power there. But I don't plan on large heater appliances like a coffee make or such. More or less small table lamp, laptop, charge a cellphone, charge AA batteries for cameras, or maybe charge the video camera up. I know the setup runs my little TV just fine. So I'll have enough power to fire up the A/D signal converter and TV or DVD player and TV.

 

Thing is when we typically go camping is to get away from everyday work and grind so we don't try and have it all in the RV too. So if that means I got to do without maybe its for the best. But is awesome the RV is still parked in the yard unplugged from 120VAC power and and going be charging again today in the sun. One more thing not on the power bill here. Here soon I'll do a dry run in the yard when I can remain above freezing. I'll do a complete dry run without ZERO hook up and see how far I can push. Now there is the test. :wink:

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I agree, we go camping to get away. There are those rare times when it would be nice to charge and use an ipad, or the TV.. but they are rare.

 

I told the wife we could probably run the TV for 12 hours on the batteries and she said that was more than we have used it in the 2 years we have owned it.

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  • 3 months later...
  • Administrator

Well Now that I've had my test run with the RV and the solar system and quite please so far. I'm now going to modify the system a bit more. Since my RV has a single breaker for all the wall outlet in the RV it gave me an idea. :smart:  So what I'm going to do is wire in a home brew transfer switch for one circuit. For example I use this picture below which is a DPDT (Double Pole Double Throw) switch mine is a 30A with screw terminals.

 

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A. Hot leg of the inverter.

B. Neutral leg of the inverter.

 

C. Hot going to the RV.

D. Neutral leg going to the RV.

 

E. Hot leg of the city power.

F. Neutral leg of the city power.

 

What this will do is absolutely isolate the inverter from the city power and allow me to select what power source I want. I did a dry run with just using a old computer cord and wiring directly to the circuit. Presto! All outlets work and power anywhere in the RV. Even ended up having the bonus of the fridge being on that circuit too. But the fridge doesn't like my inverter complains about AC HI. So no biggy just force it to LP mode (propane) and not worry about it. Anyways it would eats the batteries in very short order. The little time I got the fridge to run the inverter handled the load but the volts where falling fast. So I got to pick up some small wiring supplies in the near future and finish this small project.

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