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Open Roads Forum  >  Fifth-Wheels

 > Wanting solar for fifth wheel..help!!!!

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trucker LOU

Calif.

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Posted: 03/03/12 09:42pm Link  |  Print  |  Notify Moderator

Hey Jersey shore, for 25'do not go lighter than 6 ga wire. for a few bucks more and LOTS less line loss 4 ga welding cable is good choice. I have 2 of the 68w Unisolar laminate panels and they work very good-------Lou-------

smkettner

Southern California

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Posted: 03/03/12 10:43pm Link  |  Print  |  Notify Moderator

With a Morningstar MPPT and MC4 connectors on those panels you are best to run in series with standard #10 wire direct to the controller.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675 watts solar
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me2

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Posted: 03/04/12 07:28pm Link  |  Print  |  Notify Moderator

Sun Electric has panels for $1 per watt.
http://www.sunelec.com/solar-panels-c-5.html

I'm running the BZ 25A MPPT controller. It sells for a bit over $100. Its working fine as far as I can tell. I'll take more measurements this summer.

jdiffend

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Posted: 03/04/12 08:53pm Link  |  Print  |  Notify Moderator

I forgot to mention, there are multiple types of solar panels.
Link

jdiffend

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Posted: 03/04/12 02:43pm Link  |  Print  |  Notify Moderator

I started planning on adding solar to my 5er long before I bought it. There is a lot to read out there, some of it's good and some isn't.

Handy Bob's Blog is one of the best sources (previously linked to in this thread), but Bob's not very good at summarizing so you kinda have to pick through things.


This is just a quick overview of what I've learned but it should give you an idea of what to look for while you are reading:

1. Go with the heavier gauge wire and keep wire runs as short as possible. DC voltage drops a great deal in a short distance. If you actually do the math you'll be amazed at how much difference a few feet or a different gauge of wire makes. Frankly, 4 or 6 gauge work a lot better than 10.

2. Buy a decent controller that actually fully charges your batteries without cooking them. Reading a lot of similar threads, blogs, and reviews will help you decide which brands and models are best. I'm still deciding for myself on what controller to use.

3. Good batteries are well worth the money. Read up on what types of batteries people have tried, how well they work, and how long they last. If your batteries don't get fully charged, they won't last as long. There are some pages dedicated solely to how to properly wire batteries.

4. Place your panels carefully to avoid obstructions. Shadows = lost power and even a small shadow can make a surprising amount of difference. A drop of a few volts could mean you charge your batteries slower or you charge fewer hours a day. That can lead to batteries gradually loosing power over several days.

5. Wiring in series will help keep voltages high if you have to run wires greater distances. However, you need a controller that handles the voltage. If you only have two panels, wiring is series or parallel and you just have to decide what is best for your setup. If you have more panels then things can get complicated since you can wire partially in series and partially in parallel.

6. Panels tilted towards the sun collect more energy so if you buy mounts that let you tilt your panels, you won't need as many panel watts for the same electricity. Just remember to lower them before you move if you go that route.

7. If you don't have to power a refrigerator with electricity, you can get by with fewer watts. You'll use more propane but you'll probably have to refill that on your trip anyway. My 5er has a residential style fridge (electric only) so I'm stuck. I haven't hooked up the killawatt to see where I stand just running the fridge. I guess that will give me something else to do today.
Things like CPAP machines would require similar planning and a Killawatt is a great way to see where you stand with regularly used appliances.

One of the best places to start is to calculate how much power you need and plan your system from there. Just remember, wattage rating on panels are best case and they probably won't collect as much energy installed on your RV.

If any of this is wrong I'm sure people will happily point out how wrong I am.

* This post was edited 03/04/12 08:47pm by jdiffend *

JackandJulie

West Virginia..barely!!

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Posted: 03/03/12 11:32pm Link  |  Print  |  Notify Moderator

Thanks everyone!!!

cruz-in

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Posted: 03/06/12 08:14am Link  |  Print  |  Notify Moderator

jdiffend wrote:

cruz-in wrote:

smkettner wrote:

With a Morningstar MPPT and MC4 connectors on those panels you are best to run in series with standard #10 wire direct to the controller.


concur higher voltage equals less amps needed to transfer same power and less line loss

Perhaps I'm mistaken, but I believe the voltage drop is the same.
However, you keep the volts high enough to charge in lower light conditions so you will be charging earlier, later, and possibly overcast conditions. Maybe I'm wrong though.

This should help compare different gauge wire, 12v vs 24v, etc...

http://www.csgnetwork.com/voltagedropcalc.html


That is not my undersatnnding, it is simple Ohms law

V=IxR

R = Resistance of the wire
I = Current thru the wire
V = Voltage drop

Less current thru the wire, the less the voltage drop. Higher voltage panel require less current to deliver same power. Power is voltage times amps

P=VXI

As an example, a 48 volt panel delivers the same power as a 24 volt panel with half the current (I) of the 24 volt panel. Consequently half the voltage drop.

jdiffend

Denver, CO

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Posted: 03/05/12 08:29pm Link  |  Print  |  Notify Moderator

cruz-in wrote:

smkettner wrote:

With a Morningstar MPPT and MC4 connectors on those panels you are best to run in series with standard #10 wire direct to the controller.


concur higher voltage equals less amps needed to transfer same power and less line loss

Perhaps I'm mistaken, but I believe the voltage drop is the same.
However, you keep the volts high enough to charge in lower light conditions so you will be charging earlier, later, and possibly overcast conditions. Maybe I'm wrong though.

This should help compare different gauge wire, 12v vs 24v, etc...

http://www.csgnetwork.com/voltagedropcalc.html

RoyB

King George, VA

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Posted: 03/05/12 07:00am Link  |  Print  |  Notify Moderator

I have been working up to getting solar panels. I learned real quick there isnt "ONE" simple thing you can do to be successful camping off the power grid. I suspect just installing solar panels will not be the only thing you have to deal with. With this in mind and the fact that most camp grounds have generator use restrictions I decided to beef-up my battery system first including "smart-mode" converter/charger, bigger battery cables, bigger battery capacity (presently running 255AH but my goal is to get it up to 450AH), changed out all incandescent bulbs for LEDs, Installed a couple of Inverters, etc. we been doing alot of camping in the woods off the power grid for the past three years now with this setup. Of course I have to run my 2KW Generator everyday for 2-3 hours to re-charge my battery bank back to its 90% charge state. It appears I am using around 250-300WATTS of power from the battery bank between generator run times allowed..

This has provided me with all the problems associated with living off my batteries as to what I can expect to use and not use. Adding solar panels is only icing on the cake now. I really think all I will need is about 125WATTS of solar power to help out trickle charging my battery bank during the daytime when I am not allowed to run my generator at the camp sites.

We have got it down pretty good now for successful camping off the power grid... We actually do amost everything we like to do at the electric camp sites except NO air conditioning and NO high wattage Microwaves. Other than those two major items we run just about everything else off the Inverters and Batteries. It appears that beefed-up battery systems and solar panels sort of go hand in hand.

The only thing I havent had much off the power grid experience with is the Furnace operations. The Furnace blower is a big power drain off the battery if you have to run the blower all night long. Mine draws around 6-8AMPS of power from the battery bank to run the blower. Where we usually camp is not in the severe cold weather climate so we get away with electric blankets running off the Inverters and minimum use of the furnace. The furnace is too noisy for us to use anyway - also way to much heat as well... If I had to run my trailer furnace all night now I would probably only get to run a few lights in the evening and not many of the other 12VDC and 120VAC items.

My final battery capacity upgrade to around 450AH capacity will surely help this problem alot.


My Posts are IMHO based on my experiences - PM me
Roy and Carolyn
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cruz-in

Southern Maryland

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Posted: 03/05/12 09:43am Link  |  Print  |  Notify Moderator

smkettner wrote:

With a Morningstar MPPT and MC4 connectors on those panels you are best to run in series with standard #10 wire direct to the controller.


concur higher voltage equals less amps needed to transfer same power and less line loss

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