Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-18-2015, 11:46 PM   #29
Rivet Master
 
rodsterinfl's Avatar

 
2006 25' Safari
Fort Myers , Florida
Join Date: Oct 2011
Posts: 2,429
Images: 8
I do not mean to argue with you. Your advice has been very helpful. I became concerned while planning this project as it was a point of issue to be reviewed. What I hear you saying is to tweak every ounce of power from those panels go with larger wire. No issues. There were a few though that were telling me that DC was totally different from AC power, I had to use 00 wire, etc for my one panel! I just try to glean info from those that know and deal with conflicting info. I appreciate you and your knowledge on this stuff. No worries.

Here is my wire setup on the single panel- max 8.84 amps, 10 gauge wire with 16.5' run to controller with 1'- 10awg cable run from controller to batt terminal (bus) wired with large battery cables- length within 1.5' of battery.
__________________

__________________
WBCCI 8653/AIR 60240
2017 Ford F-150 3.5 Ecobeast Gen 2 3.55 Platinum
rodsterinfl is offline   Reply With Quote
Old 06-18-2015, 11:52 PM   #30
Rivet Master
Commercial Member
 
lewster's Avatar
 
Vintage Kin Owner
Naples, FL , Hood River, OR
Join Date: Dec 2005
Posts: 7,281
Quote:
Originally Posted by rodsterinfl View Post
I do not mean to argue with you. Your advice has been very helpful. I became concerned while planning this project as it was a point of issue to be reviewed. What I hear you saying is to tweak every ounce of power from those panels go with larger wire. No issues. There were a few though that were telling me that DC was totally different from AC power, I had to use 00 wire, etc for my one panel! I just try to glean info from those that know and deal with conflicting info. I appreciate you and your knowledge on this stuff. No worries.
Rod, No offense taken. Everyone knows that whatever information that is placed on the Web is to be taken as gospel, regardless of the source!

You take what works best for you and live with the results.
__________________

__________________
Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist...Micro Air 'Easy Start' Sales and Installations
lewster is offline   Reply With Quote
Old 06-20-2015, 10:28 AM   #31
1 Rivet Member
 
Oakland , California
Join Date: May 2014
Posts: 13
Quote:
Originally Posted by rodsterinfl View Post
I just wanted to share this about the prewire and his assessment of it when he looked at it tonight. While it's true about needing larger wire for greater power or decreasing resistance, it is not going to matter with a roof system using the prewiring up to about 200 watts or 12 amps.

Rodster -- can you please ask him whether he thinks 300 watts or 18 amps would be safe with the prewire? Curious minds want to know!
__________________
mikebee is offline   Reply With Quote
Old 06-20-2015, 01:13 PM   #32
Rivet Master
 
2015 30' Classic
Pleasanton , California
Join Date: Jan 2015
Posts: 618
Hope you don't mind me sticking my two cents in here but when using #10 AWG wire, the maximum carrying currrent for power transmission is 15 A. These are very very conservative guidelines. Could you get away with pushing 18 A through #10 wire, sure. But let's look at your losses.

I've been thinking about how to discuss losses with regard to solar installations and I think the best way is to represent losses is in terms of power. Why, because in a solar configuration you're goal is to convert the sun's solar energy into power at the solar cells, and then convert this power again to charger your batteries.

So if you intend on using #10 AWG wire and let's say you have a total of 40 feet of wire. Your resistance will be 40 ft * .001 ohm/ft = .04 ohms. Your power losses, just due to the #10 AWG pre-wire (neglecting all other losses) will be P = I*I*R = 18 * 18 * .04 = 13 W. Since your total power is 300 W, the losses to the pre-wire are (13/300)*100 = 4.3%. This isn't an outrageous loss, but considering there are other losses in the system you might not want to throw away 4.3%.

So here's the beauty of an MPPT system... If you connect your two panels (I'm guessing you're considering two 150W panels) in series, then the current stays the same, 9 A, but the voltage doubles. So now your power losses in the pre-wires are 9 * 9 * .04 = 3.24 W, which is only (3.24/300)*100 = 1.08% of the total. By connecting your panels in series you've reduced your pre-wire losses by a factor of 4!

This assumes you're using an MPPT solar charger that can handle the voltage of two panels in series.

Hope this is helpful.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
alano is offline   Reply With Quote
Old 06-20-2015, 01:28 PM   #33
BAB
Rivet Master
 
BAB's Avatar

 
2015 30' Classic
2012 28' International
Greensboro , North Carolina
Join Date: Aug 2011
Posts: 1,574
Found it interesting that at the annual session with the Airstream execs (Alumapalooza, last month), they admitted that it was time for them to get serious about the solar package that they are installing. It really is pretty puny given the demands of the 12V system of some of the trailers -- like the '15 Classic. You need 12V for a LOT of stuff, including the power awning, power stabilizers, power recliners, etc. I found after 3 weeks with my 600W AM solar package and my Magnum MSH inverter, 4 Lifeline 6V batteries, my batteries never fell below 45%. Really only needed my generator for the A/C. Solar easily covered everything else.
__________________
_________________
"SilverLeaf II" 2015 30' Classic
2014 RAM 2500 Laramie 4x4 CC w/6.7L Cummins
ProPride 3P
AIR# 58452
WBCCI # 3430-Unit 21
BAB is offline   Reply With Quote
Old 06-21-2015, 08:46 AM   #34
Rivet Master
 
rodsterinfl's Avatar

 
2006 25' Safari
Fort Myers , Florida
Join Date: Oct 2011
Posts: 2,429
Images: 8
Quote:
Rodster -- can you please ask him whether he thinks 300 watts or 18 amps would be safe with the prewire? Curious minds want to know!
I just asked him and he said that the power source will probably not be continuously producing the extra three amps (above spec) and he wouldn't worry about it on the length of run in "those trailers".

He started telling me again how 10 awg is used in large generator circuits to carry up to 30 amps, usually short runs but nonetheless.

So there you have it. His Father's Day opinion.

@BABS:

Quote:
Really only needed my generator for the A/C. Solar easily covered everything else.
That is my goal, though my needs are much lighter. In a lengthy phone meeting with Renogy I spelled out my projected daily need and they came up with a solar requirement of 236 watts. Naturally this did not include AC or toaster use. They recommended a system of 300 watts to slightly overkill the need. I will use the generator for higher wattage items like AC or alternative toast making methods! In your case, that's the problem with having a Cadillac with all the options, all that power requires more more more!

It all depends on what kind of system someone wants to build out. I wanted to maximize my use of the current battery system without adding more batteries. I have the ability with my system to add more in the future but for now it is enough. My 70 amps usage is 80% of the current batteries' available capacity so I am good. The system follows the 8-10 times rule- 18 amp solar capacity/184 amp storage/110 amps available for use.
__________________
WBCCI 8653/AIR 60240
2017 Ford F-150 3.5 Ecobeast Gen 2 3.55 Platinum
rodsterinfl is offline   Reply With Quote
Old 06-23-2015, 07:55 AM   #35
BAB
Rivet Master
 
BAB's Avatar

 
2015 30' Classic
2012 28' International
Greensboro , North Carolina
Join Date: Aug 2011
Posts: 1,574
Rod, you do an amazing job with the science of electrons! It is very easy to get spoiled with the goodies, but there is definitely seems to be some infinite loop associated with power stuff. Add a goody, figure out how to power it! My buddy Gary finished upgrading his electrical system with solar AND lithiums. That will be my next step, hopefully the 6V Lifelines will last long enough for lithium prices to drop out of the stratosphere.
__________________
_________________
"SilverLeaf II" 2015 30' Classic
2014 RAM 2500 Laramie 4x4 CC w/6.7L Cummins
ProPride 3P
AIR# 58452
WBCCI # 3430-Unit 21
BAB is offline   Reply With Quote
Old 06-23-2015, 08:07 AM   #36
Rivet Master
 
switz's Avatar

 
2014 31' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 4,799
Images: 8
Another tidbit concerning solar is that the battery system amp hours rating should be at least 75% of the total solar panel wattage. Thus we have a 600 amp hour lithium battery with 800 watts of solar on the roof. The wire size coming down from the solar panel roof junction box is #2 copper. The wire size between the battery and the Magnum, a distance of less than two feet, is 4-0.
__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels
switz is offline   Reply With Quote
Old 10-15-2015, 12:43 AM   #37
Rivet Master
 
2015 30' Classic
Pleasanton , California
Join Date: Jan 2015
Posts: 618
Ok, let's do the math again. 10 AWG wire has a resistance of 1 ohm / 1000 ft. Four Renology panels configured as two in series paralleled with another two in series result in an optimal current of 10.6 A and voltage of 37.8 V.

In my 30' Classic I conservatively estimate the pre-wire length to be 35 ft per conductor. So 70 ft equals 70 milliohms and this results in a voltage drop of 10.6 A * 0.07 ohms = 0.742 V. So the voltage loss due to the pre-wiring is .742/37.8 = 1.96%

You'll probably also hear that series connected panels are not as good as parallel connected panels. Another wives tale where there's no field data that's reliable.

Conclusion: if you can DIY a system go ahead and reuse the existing wiring in a series connected configuration with an MPPT controller.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
alano is offline   Reply With Quote
Old 10-15-2015, 12:53 AM   #38
Rivet Master
Commercial Member
 
lewster's Avatar
 
Vintage Kin Owner
Naples, FL , Hood River, OR
Join Date: Dec 2005
Posts: 7,281
I prefer to use the stated requirements of the manufacturers of the equipment that I'm using. This specifically includes solar charge controllers and inverter/chargers.

You might find this table of interest; taken from Pg. 8 of the Blue Sky Energy 3024iL manual: (slightly mis-aligned, but you get the picture!). Perhaps some folks think that they have better answers than the equipment manufacturers that they use. Maybe they should offer their services to the OEMs!

12VDC System 24VDC System
Feet/Meters
12AWG 4.0/1.2 10.7/3.3
10AWG 6.4/2.0 16.9/5.2
8AWG 10.1/3.1 26.9/8.2
6AWG 16.1/4.9 42.8/13.0
4AWG 25.5/7.8 68.1/20.7
2AWG 40.6/12.4 108.2/33.0
1/0AWG 64.6/19.7 172.2/52.5

Pay particular attention to the line in red, which is for the 10AWG that Airstream uses as their solar pre-wire. For a 12VDC parallel connected solar array, you need 6.4' maximum run or less to achieve 3% voltage drop. For a 24VDC series/parallel array, you need 16.9' or less for 3% voltage drop or less. Still thinking of using the solar pre-wire????

And BTW, parallel connections vs. series is no "wives tail"! If you even partially shade one of a series connected pair of panels on an RV roof, you loose the output of the majority of that string. Loose a single panel in a parallel connection and you only miss the output of that single panel. Series connections might be great for free-stanging residential solar arrays, but almost every RV installation will be subject to some shading over the course of a day, unless you have a 40' motor home or huge 5th wheel with a veritable dance floor of available space.

The folks at AM Solar, with 28 years of specific experience in the RV solar business and thousands of RV solar installations have tested this extensively. Their conclusions are that more usable wattage is recovered from parallel connected panels.

Folks, of course, are free to use what ever systems they want. I would rather defer to proven experience.
__________________
Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist...Micro Air 'Easy Start' Sales and Installations
lewster is offline   Reply With Quote
Old 10-15-2015, 01:55 AM   #39
Rivet Master

 
2007 22' International CCD
Corona , California
Join Date: Jul 2013
Posts: 3,322
Which is exactly why we didn't bother looking for the 'top end' of the dinky factory pre-wire when I installed solar on our AS. We used the nice heavy wire that came with the AM Solar kit. Bigger wire is better, period. And yes, I am an electrical engineering type person...


Sent from my pocket Internet using Airstream Forums
__________________
KE4GNK/AE
'The Silver HamShack' (2007 International 22FB CCD 75th Aniversary model)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch
2012 shortbed crewcab 4x4 Toyota Taco TV with more antennae on it
rmkrum is online now   Reply With Quote
Old 10-15-2015, 08:06 AM   #40
4 Rivet Member
Commercial Member
 
acstokes's Avatar
 
2009 30' Classic
Melbourne, FL , Searsport, ME
Join Date: Jul 2013
Posts: 309
Maybe someone can answer this question that's been puzzling me:

I'm no solar guru, but I've installed 2 systems of my own, one was 360 watts and the other 600 watts. The inverters were 1000 watts and the batteries used were 2-Lifeline 6v totaling 300ah. I would've added two more batteries if I had had more room in the front of my trailer near the inverter and DC breaker panel. I wired all panels in parallel and used #4 AWG for the run from my combiner to the MPPT controller. Once I used a Blue Sky controller and the second time a MidNite Solar controller...both American brands. I know some will say I should have used a Magnum controller, but I didn't want to pay the additional expense and I only needed a 1000 watt inverter.

I was puzzled by the fact that both the Blue Sky and MidNite Solar controllers would only accept wire size of up to 10 AWG for both input and output wires. After the expense of buying marine-grade #4 wire I had to downsize to #10 to connect to these controllers. Why aren't these controllers designed to accept up to at least #4 or #6 wire? Am I missing something here?

By the way, what size wire will Magnum controllers accept?

Thanks for your suggestions.
__________________
Fred Stokes
RV Rearview Camera Systems, LLC
WBCCI #2810
acstokes is offline   Reply With Quote
Old 10-15-2015, 08:22 AM   #41
Overland Adventurer
 
AtomicNo13's Avatar
 
1991 34' Excella
2009 34' Panamerica
Telluride , Colorado
Join Date: May 2012
Posts: 1,885
Quote:
Originally Posted by rmkrum View Post
Which is exactly why we didn't bother looking for the 'top end' of the dinky factory pre-wire when I installed solar on our AS. We used the nice heavy wire that came with the AM Solar kit. Bigger wire is better, period. And yes, I am an electrical engineering type person...


Sent from my pocket Internet using Airstream Forums
EE type person?
__________________
AtomicNo13 is offline   Reply With Quote
Old 10-15-2015, 11:40 AM   #42
Rivet Master
Commercial Member
 
lewster's Avatar
 
Vintage Kin Owner
Naples, FL , Hood River, OR
Join Date: Dec 2005
Posts: 7,281
Quote:
Originally Posted by acstokes View Post
Maybe someone can answer this question that's been puzzling me:

I'm no solar guru, but I've installed 2 systems of my own, one was 360 watts and the other 600 watts. The inverters were 1000 watts and the batteries used were 2-Lifeline 6v totaling 300ah. I would've added two more batteries if I had had more room in the front of my trailer near the inverter and DC breaker panel. I wired all panels in parallel and used #4 AWG for the run from my combiner to the MPPT controller. Once I used a Blue Sky controller and the second time a MidNite Solar controller...both American brands. I know some will say I should have used a Magnum controller, but I didn't want to pay the additional expense and I only needed a 1000 watt inverter.

I was puzzled by the fact that both the Blue Sky and MidNite Solar controllers would only accept wire size of up to 10 AWG for both input and output wires. After the expense of buying marine-grade #4 wire I had to downsize to #10 to connect to these controllers. Why aren't these controllers designed to accept up to at least #4 or #6 wire? Am I missing something here?

By the way, what size wire will Magnum controllers accept?

Thanks for your suggestions.
AC,

The missing link in your system is the use of spade connectors for larger cable sizes. We use 6AWG for the Blue Sky 2512iX-HV controllers and the appropriate spade connectors that allow the larger cabled to be inserted into the small screw-clamp connectors.

The larger 3024iL controllers will accept bare cable ends up to 2AWG with no additional connectors.

Can't address the Magnum solar controller, as I haven't used one yet.
__________________

__________________
Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist...Micro Air 'Easy Start' Sales and Installations
lewster is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Location of Solar Pre-Wire. Where are the wires? kscherzi Generators & Solar Power 10 06-02-2013 05:06 PM
2010 28' International Solar Pre Wire ?? tlcbuilder 2006 - 2010 International 1 09-23-2012 04:02 PM
Solar pre-wire on a 2005 19' Bambi CCD JDL Generators & Solar Power 23 12-22-2010 06:50 AM
Solar pre wire bwaysteve Generators & Solar Power 7 11-21-2010 08:06 PM
Solar Pre-wire 2008 Safari 25 FB SE - Good enough? eheffa Generators & Solar Power 3 10-23-2009 11:30 AM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 06:57 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.