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Author Topic: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?  (Read 2433 times)

tanglemoose

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We are considering upgrading our Cougar to the Keystone RV Cougar Travel Trailer, 24sabwe, the 2020 comes all pre wired... for panel on roof, inverter, etc. Dealer was quoting me a 2000 inverter, 160 watt panel and 2 6 volt batteries... does this sound like this package would work... seems like inverter is pretty strong?? And just 160 watts???

https://www.keystonerv.com/fifth-wheels/cougar/solar/

We have now a 150 watt, 600 inverter. And 2 6 volts.. which does us pretty good, but would like to run TV, say 4 hours a day... have not tried that with our existing solar... don't think it would be enough...

Thoughts... put link on for anyone who wanted to see what I was talking aoout. Like the pre-wire, should save installation costs, as we don't do ourselves!

Thanks! Threatening snow here in Montana tonight, ready to head south!!!
« Last Edit: September 20, 2019, 06:34:46 PM by tanglemoose »
Donna and Mark
and our Golden Lexie
New 2017 TT Keystone Cougar  Same model... but NEW Features!
2015 Keystone Cougar 1/2 Ton Series, 21rbswe, 26'
2013 Toyota Tundra
Living in Cold Montana Country.....

Kevin Means

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #1 on: September 21, 2019, 02:18:10 AM »
A lot depends on where you'll be camping and the time of year. The winter sun is a lot lower in the sky in Big Sky country than say, in Arizona, and Montana winters average a lot more cloud cover than in AZ. Those are huge factors for solar users.

Four hours of TV doesn't require a lot of battery power, but when combined with parasitic loads, cell phone/tablet charging, inverter, fridge, lights etc, it adds up. If your goal is to replenish just some of the power you use, only you can say whether or not you'll be happy with a 160 watt panel. If your goal is to replenish all the power you use, you'll first need to determine how much power that is (easy enough) then size your solar and battery bank accordingly.

Note: Some "solar ready" setups leave something to be desired - with very thin gauge wiring. Others are OK.   

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ
RVI Brake 2, TST 507 TPMS, 960 watts of solar, SolaRVector tilt
Lakeside, California

Heli_av8tor

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #2 on: September 21, 2019, 07:49:18 AM »
I suspect this falls into the latter category.

Who designs a system with a 2000 watt inverter then only has two 6 volt batteries (presumably GC2ís)?
Then only provides a single  160 watt panel to charge them?

First answer the questions Kevin presented to yourself. Then you can determine if the batteries and charge system are adequate for you.

Iíd inquire about the gauge of the wire from the panel to the charge controller and if thereís room and weight capacity for adding batteries. Then you will know (or can query the Forum) whether itís really prewired for your requirements.
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

Gary RV_Wizard

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #3 on: September 21, 2019, 11:02:59 AM »
Just because a system has a 2000W inverter capacity doesn't mean you have to use 2000W all the time. Anymore than you need to use all 12,000 watts if you have a 50A shore power, or all 400 of an engines rated max horsepower.  Just don't let it fool you into thinking you run almost anything, any time. Most modern inverters are efficient enough that there is little or no penalty for having extra inverter capacity available, whether for future expansion or for brief high loads.

The battery bank size (amp-hours) sets the practical limit of how much power can be consumed while off-grid, but it can always be expanded (assuming physical room). As Kevin says, only you can figure out how much power you routinely use and whether 210-225 AH (two GC2 6v batteries) is enough for your needs.


Ditto for the 160W panel, which you should think of as a battery charger. If you have enough sun-time, a 160W panel will charge any 12v battery bank nicely. The only question is how long it takes. If you only have two hours/day of usable sunshine, then you need a lot more panel wattage than you would if you have 10 hours.


I like the bank account analogy for boondocking energy management.   Consider the batteries to be your bank account balance. You withdraw from the battery bank using the inverter and other DC appliances (lights, circuit boards, furnace fan, etc.) and make deposits with the solar panel or the shore power converter/charger. You can only take out as much as you put in, and you have to put it in before you can use it.  There are no loans to be repaid by future deposits!
« Last Edit: September 22, 2019, 09:48:31 AM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

tanglemoose

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #4 on: September 21, 2019, 11:50:01 PM »
Thanks for comments and suggestions...

Had a dealer quote 2 lithium 100 ah batteries, 879.00 each.... what is in them... gold?? Do you need those type of batteries? Some Lion brand...

As to our sun, we will Not be in Montana.. ha... headed south with our Rv...  know less sun time with dark at 5.30... ugh... but in a sunny warm place...

I will ask the wire gauge question thanks for that suggestion. As to the bank. I always like to withdraw before making deposit, now your telling me that wont work with solar??? I never quite understand the watts in, out, etc.
Yes, we do use our laptop a little, depending where we are... maybe an hour a day, if course, lights, etc. Etc. We are very low maintenance people though... 
I am thinking 380 watts, 2000 inverter and 2 6 volt batteries.... thoughts????
Donna and Mark
and our Golden Lexie
New 2017 TT Keystone Cougar  Same model... but NEW Features!
2015 Keystone Cougar 1/2 Ton Series, 21rbswe, 26'
2013 Toyota Tundra
Living in Cold Montana Country.....

Gary RV_Wizard

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #5 on: September 22, 2019, 09:39:35 AM »
Quote
Had a dealer quote 2 lithium 100 ah batteries, 879.00 each.... what is in them... gold?? Do you need those type of batteries? Some Lion brand...
Not gold, but lithium. Lithium-Iron Phosphate, to be accurate. Plus a circuit board, cause it needs a Battery Management System if used as a plug-in replacement for a lead acid battery. It's a very pricey package, but it outperforms a lead acid battery in many ways. It is only about 1/3 the weight, can be recharged 3x-4x as many times as the best lead-acid battery, and can be discharge far more deeply so you need fewer of them for a given number of Amp-hours capacity.
He probably quoted the Lion brand battery:    https://lionenergy.com/products/lion-safari-ut

Do you need those?   Not at all, but they are just about the best that money can buy and will probably last you 10-12 years.  But you could buy three (or even four) of lead-acid AGM 12v for around $275 each and get about the same capacity and probably get 6-8 years of life, so the economics of Lithium Ion batteries are still marginal for most RV owners.   
« Last Edit: September 22, 2019, 09:45:41 AM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Mark_K5LXP

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #6 on: September 22, 2019, 10:10:21 AM »
I always like to withdraw before making deposit, now your telling me that wont work with solar??? I never quite understand the watts in, out, etc.

If you're going to play in the solar sandbox you're going to have to know and understand how the sausage is made.  You *can* connect arbitrary components and go by trial and error but it goes a lot smoother when you're working within the limits of a system deliberately put together.  You can base your faith on a majority opinion of strangers on an internet forum, or understand and know your own needs and goals and not have to wonder or guess.  If you can find a trustworthy consultant that can work, but you're still going to have to provide some degree of technical usage data.  And unless the consultant travels with you, monitoring and running the system is going to be on you.  Having just a rudimentary understanding of the systems goes a long way towards using them successfully.

If you can work through these I think you'll have a great foundation.

12V Side of Life, parts 1 & 2:
http://www.marxrv.com/12volt/12volt.htm
http://www.marxrv.com/12volt/12volta.htm

Mark B.
Albuquerque, NM

Gizmo

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #7 on: September 22, 2019, 04:30:20 PM »
You have received some accurate information to consider from previous posters.  As to whether lithium is worth it here is my experience and thoughts.  When we were recreational RV'ers I did install solar on my previous rigs as we boondocked frequently, but felt the lithium batteries were too expensive for recreational use and found the lead acid and later AGM batteries were just fine.  That all changed when we went full-time at which point I could justify the salty price and very happy. 
Regards, Bruce, Lin An, Kenji & Suki
2015 Ram Big Horn 3500 CC Cummins TD Dually 3:73 Gears & AISIN Tranny
2019 Grand Design Solitude 310GK-R

solarman

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #8 on: September 23, 2019, 07:37:24 AM »
I suspect this falls into the latter category.

Who designs a system with a 2000 watt inverter then only has two 6 volt batteries (presumably GC2ís)?
Then only provides a single  160 watt panel to charge them?

well no one "designs" such a system, it's put together by ignorance and guesswork.
this seems to be the RV manufacturers mantra with solar. it's clearly seen by them as a sales/marketing gimmic
and just another source of revenue.

although i'm biased as a professional, I can say from personal experience that the OEM installed systems are garbage.
if there are any RV manufacturers reading this forum then my advice is to WAKE UP and employ the services
of a professional engineer to design the basis of a system that might actually be useful.

secondly, a pair of FLA GC2's cannot supply enough current for a 2000 W inverter save for a few minutes.
this is battery abuse at it's finest..



KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

Gary RV_Wizard

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #9 on: September 23, 2019, 08:55:03 AM »
Quote
secondly, a pair of FLA GC2's cannot supply enough current for a 2000 W inverter save for a few minutes.
this is battery abuse at it's finest..
Very true, but those batteries can supply 200-400 watts/hour for an evening, enough to watch some tv, surf the internet awhile, or charge phones.   They put a 2000W inverter in for sales bragging purposes, but there is only a small downside to having the extra capacity.   IMO the biggest negative is that under-educated owners are all-too-likely to try to use all 2000W and crash the system. A large percentage of people just turn on appliances & lights until things stop working and those folks will get into trouble with a large inverter and small battery bank.  Plus this is aided by inflated claims of RV sales people (2000W - you can do anything!).
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

garyb1st

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #10 on: September 23, 2019, 09:06:14 AM »
As Kevin says, location is important.  We purchased a small 100 watt solar suitcase before our last 3+ month trip to the Midwest and back.  We began this trip June 1 from the L.A. area.  After the first three weeks of relatively sunny West Coast weather, we encountered our first rain.  That was in southeastern South Dakota.  For the next two months, it was high wind, rain or clouds.  I think I used the solar maybe 3 or 4 times before we got to the Dakotas.  From then on, it wasn't worth the effort. 

Not suggesting rooftop solar is not worth the money.  However, for comparison purposes, my DIY costs for the solar suitcase, a 1000 Pure Sine Wave inverter, heavier wire etc., was probably less than $600.00.   
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler


Poverty exists not because we cannot feed the poor, but because we cannot satisfy the rich.

UTTransplant

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #11 on: September 23, 2019, 10:44:51 AM »
Kevin is a retired electrical engineer. He never worked on power projects, just aircraft electronics, but the basics were there. Our first experience with solar was a 300 watt installation on an Outdoors RV travel trailer that was ďpre-wired for solarĒ. A joke. The wire was far too small. He ran new wiring through the refrigerator vent and an empty spot behind the bed headboard, plus we changed the single 12v to two 6 volt batteries. The 300 watts flat mounted panels served us well for 3 years we had the unit. With the new motorhome we have a residential refrigerator and a number of other power hungry components, plus we want our comforts on our 3-4 month trips. We had six 6 volt batteries installed during the unit build. Kevin installed a Progressive Industries EMS, a VictronConnect battery monitor, Renogy MPPT solar controller, and 900 watts of flat mounted solar. We get by fine on sunny days, but we need to run the generator about an hour or so on cloudy days. Since the convection oven requires the generator when dry camping, I manage to do my baking then too. We would be more efficient if the panels could be raised, but ...
Pam and Kevin plus Lily the cat
2018 Tiffin 37PA
2018 Jeep Grand Cherokee Trailhawk toad
https://toobusyforwork.com

Heli_av8tor

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #12 on: September 23, 2019, 01:17:23 PM »
Pam,

The other "Kevin" can help with that.   ;)
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

tanglemoose

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #13 on: September 23, 2019, 10:18:11 PM »
Just so enjoy reading all your suggestions, links, etc... I will really have to check the wiring that is going in the new units. Hopefully they have made some improvements to the wiring in this 2020 unit, but I am not counting on it after reading all your notes!
We had our last system installed by Park County RV, he doesn't sell units, just does repairs and solar for about 13 years... We trusted his advice last time and will do the same. We are not hungry power users as we read thru the articles... I don't expect to run the coffee maker or microwave when we are boondocking, but would like a little TV time without our generator running. We need to get a battery monitor besides the GoPower Controller that let's us know what the battery charge is, but not a lot of other information. Our controller usually charges up to 13.6V and we go down to 12 in the am, so I am guessing we do have some money in the bank to use on the TV and satellite dome and receiver. Guess I need to read more on the controller and see what is a good volt to have and what is "low". We have 150 watts of solar on roof and usually do very well with it, generator is used very little. Once in a while we want more shade while camping. So, are thinking a suitcase of Solar would be good to add on. To just charge up the batteries faster on days when I might want to charge my laptop and to point toward sun while hiding the RV in the shade.  We did not find a lot of shade in Nevada and northern Arizona last year though!

Our son in law put some gizmo on his battery that he can monitor and watch thru his phone. Guess we need to be better at determining our usage. But after looking at those usage guides, we don't use much! LED lights on only when needed, water pump is off with pitchers full of water to use instead of constantly turning on pump (pump is noisy) coffee made on propane stove. We are pretty happy campers with our solar, except would like to be able to watch a little TV... We will be out for 3 solid months, need some TV time!, ha, somebody in our camper does!

Thanks everyone!!
Donna and Mark
and our Golden Lexie
New 2017 TT Keystone Cougar  Same model... but NEW Features!
2015 Keystone Cougar 1/2 Ton Series, 21rbswe, 26'
2013 Toyota Tundra
Living in Cold Montana Country.....

Gary RV_Wizard

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #14 on: September 24, 2019, 08:02:50 AM »
The solar gurus will grit their teeth at this, but IMO solar doesn't need sophisticated gear if your power needs truly are modest. However, many people come here and say they don't need much, but upon questioning their demands grow substantially.  Few have any real notion of how much power they consume and are shocked if they actually do monitor and record what they actually use on a typical day.  Nor do they have much awareness of the amount of sunlight available where they will camp, in terms of both hours/day and direct vs diffused sunlight.  It's natural to think that the sun is out, so solar energy ought to be available.

"A little tv time" isn't that much power consumption, maybe 100 watts/hr for 2 or 3 hours?  That's about 20-30 amp-hours from the batteries, so a couple batteries and a 100W panel in direct sun can probably manage it and the charge amps are low enough that most any charge ontroller will be adequate. Easy power is addictive, though, and "wants" soon grow into "needs". Maybe an extra light for reading or a couple minutes in the micro to nuke some popcorn, and the down the slippery slope we go. Soon we need more batteries, 300+ watts of panels, an amp-monitor, and a controller that can deliver some serious amperage.  Then we realize that if we had just a little more of everything, we could operate much like we do when connected to the power grid, so double up everything for a "real solar system".
« Last Edit: September 24, 2019, 08:05:03 AM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

solarman

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #15 on: September 24, 2019, 09:32:15 AM »
The solar gurus will grit their teeth at this, but IMO solar doesn't need sophisticated gear if your power needs truly are modest. However, many people come here and say they don't need much, but upon questioning their demands grow substantially.  Few have any real notion of how much power they consume and are shocked if they actually do monitor and record what they actually use on a typical day.  Nor do they have much awareness of the amount of sunlight available where they will camp, in terms of both hours/day and direct vs diffused sunlight.  It's natural to think that the sun is out, so solar energy ought to be available.

"A little tv time" isn't that much power consumption, maybe 100 watts/hr for 2 or 3 hours?  That's about 20-30 amp-hours from the batteries, so a couple batteries and a 100W panel in direct sun can probably manage it and the charge amps are low enough that most any charge ontroller will be adequate. Easy power is addictive, though, and "wants" soon grow into "needs". Maybe an extra light for reading or a couple minutes in the micro to nuke some popcorn, and the down the slippery slope we go. Soon we need more batteries, 300+ watts of panels, an amp-monitor, and a controller that can deliver some serious amperage.  Then we realize that if we had just a little more of everything, we could operate much like we do when connected to the power grid, so double up everything for a "real solar system".


LOL.. true Gary, we need to triple or quad that solar..  i mean, A/C, microwave,toaster,coffee machine, 4 TV's cell phones, lights etc..

I stopped at 960 Watts to keep the wife happy, but in reality a serious boondocker will consume very little, it's nice to have the convenience
of all the appliances, but sometimes we just switch everything off and enjoy almost perfect darkness.. !

KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

Gizmo

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #16 on: September 24, 2019, 10:01:06 AM »
Agree with both of above.
Regards, Bruce, Lin An, Kenji & Suki
2015 Ram Big Horn 3500 CC Cummins TD Dually 3:73 Gears & AISIN Tranny
2019 Grand Design Solitude 310GK-R

Kevin Means

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #17 on: September 24, 2019, 12:25:50 PM »
Well, that all sounds good, but in my experience, most RVers who are new to solar (even some experienced RVers) often have the same questions and misconceptions. Having dealt with literally thousands of them, Iíve found that it really helps to have them identify exactly what their goals are. Infrequent  boondockers, for example, are often surprised to learn that really only need an additional house battery to extend their off-grid time. Many who think they want enough solar to be able to fully recharge their batteries each day, often change their minds when they realize how much itís going to cost, but that cost can vary significantly, depending on how their RV is equipped.

If you enjoy camping off grid in secluded areas as much as we do, and youíre fortunate enough to have places like that to camp, you really learn to appreciate having enough solar to not have run your generator for hours on end every day. We see it as a quality of life thing. To us, it makes little sense to go halfway with solar, because to us, there isnít much difference in having to run our generator two hours a day vs. four hours a day, but I acknowledge that that is very subjective.

Kev
« Last Edit: September 24, 2019, 12:27:59 PM by Kevin Means »
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ
RVI Brake 2, TST 507 TPMS, 960 watts of solar, SolaRVector tilt
Lakeside, California

tanglemoose

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #18 on: September 24, 2019, 05:14:35 PM »
Kevin is a retired electrical engineer. He never worked on power projects, just aircraft electronics, but the basics were there. Our first experience with solar was a 300 watt installation on an Outdoors RV travel trailer that was ďpre-wired for solarĒ. A joke. The wire was far too small. He ran new wiring through the refrigerator vent and an empty spot behind the bed headboard, plus we changed the single 12v to two 6 volt batteries. The 300 watts flat mounted panels served us well for 3 years we had the unit. With the new motorhome we have a residential refrigerator and a number of other power hungry components, plus we want our comforts on our 3-4 month trips. We had six 6 volt batteries installed during the unit build. Kevin installed a Progressive Industries EMS, a VictronConnect battery monitor, Renogy MPPT solar controller, and 900 watts of flat mounted solar. We get by fine on sunny days, but we need to run the generator about an hour or so on cloudy days. Since the convection oven requires the generator when dry camping, I manage to do my baking then too. We would be more efficient if the panels could be raised, but ...

What gauge of wire should be run in a solar system?  thanks,
Donna and Mark
and our Golden Lexie
New 2017 TT Keystone Cougar  Same model... but NEW Features!
2015 Keystone Cougar 1/2 Ton Series, 21rbswe, 26'
2013 Toyota Tundra
Living in Cold Montana Country.....

solarman

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #19 on: September 24, 2019, 08:33:45 PM »
What gauge of wire should be run in a solar system?  thanks,

how long is a piece of string ?

too many unknowns.. wire sizing is based on specific wattage, voltage and current.
even for the same panel wattage, different configurations of series/parallel arrays and
different battery voltages will require different wire gauges..
it's application specific..

 

KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

solarman

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #20 on: September 24, 2019, 08:39:53 PM »
Many who think they want enough solar to be able to fully recharge their batteries each day, often change their minds when they realize how much itís going to cost, but that cost can vary significantly, depending on how their RV is equipped.

Kev


that's basically it in a nutshell.. COST.. solar is "pay to play" and it's certainly not cheap..
KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

tanglemoose

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #21 on: September 24, 2019, 08:47:11 PM »
This system has 8 gauge wire I was told today. Thinking of 190 watts, 1200 inverter and 2 AGM batteries...

Yes, solar is pricey but a necessity in our RV, we love our solar!!  We like the sounds of the wind, birds, etc. and not our generator...
Donna and Mark
and our Golden Lexie
New 2017 TT Keystone Cougar  Same model... but NEW Features!
2015 Keystone Cougar 1/2 Ton Series, 21rbswe, 26'
2013 Toyota Tundra
Living in Cold Montana Country.....

Kevin Means

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  • SolaRVector
    • SolaRVector
Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #22 on: September 25, 2019, 01:04:22 AM »
When determining what wire gauge to use, the general rule of thumb is to not have greater than a 2% loss in voltage over the length of the wire. (Some say 3%) You hear people talk about wire gauge with RV solar a lot, because you're often dealing with relatively low voltage from the panels to the controller, and even lower voltage from the controller to the batteries. Here's a link to a simple voltage loss calculator, and an explanation of the issue. https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=2.061&voltage=12&phase=dc&noofconductor=1&distance=20&distanceunit=feet&amperes=20&x=95&y=30
 
You didn't mention the wire run length of that 8 gauge wire, and I'm assuming they're referring to the wires that lead from the roof to where the controller will be, but unless they're routing the wire on a lengthy path, 8 gauge wire is "probably" going to be fine. FWIW, I've seen 14 gauge wire on some 5th wheels that claimed to be, "solar prepped."

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ
RVI Brake 2, TST 507 TPMS, 960 watts of solar, SolaRVector tilt
Lakeside, California

solarman

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #23 on: September 25, 2019, 09:33:51 AM »
When determining what wire gauge to use, the general rule of thumb is to not have greater than a 2% loss in voltage over the length of the wire. (Some say 3%) You hear people talk about wire gauge with RV solar a lot, because you're often dealing with relatively low voltage from the panels to the controller, and even lower voltage from the controller to the batteries. Here's a link to a simple voltage loss calculator, and an explanation of the issue. https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=2.061&voltage=12&phase=dc&noofconductor=1&distance=20&distanceunit=feet&amperes=20&x=95&y=30
 
You didn't mention the wire run length of that 8 gauge wire, and I'm assuming they're referring to the wires that lead from the roof to where the controller will be, but unless they're routing the wire on a lengthy path, 8 gauge wire is "probably" going to be fine. FWIW, I've seen 14 gauge wire on some 5th wheels that claimed to be, "solar prepped."

Kev


to re-enforce Kevin's post..


again, it all depends on the panel voltage and current..

voltage drop is a function of resistance and proportional to cable length.

as an example, here are two scenarios..

off grid application..
1. 3000 Watt array, 10 panels in series for 400 V @ 8 A.  200 ft run with < 1% drop requires 10 AWG

RV application.
2. 600 Watt array, 6 panels in parallel for 18 V @ 33 A. 40 ft run with < 1% requires 3/0 conductors !!


10 AWG copper is approx $0.22 a foot. in this example wire cost round trip 400 ft * 0.22 = $88    weight = 0.042lbs/ft * 400 = 16.8lbs
3/0 AWG copper is approx $3.5 per foot. in this example wire cost round trip 80 ft * 3.5 = $280    weight = 0.65lbs/ft * 80 = 52lbs




« Last Edit: September 25, 2019, 09:41:20 AM by solarman »
KZ MXT20 480 W solar
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Gary RV_Wizard

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Re: solar now in Cougar, Keystone Rvs. OTG is an option.. anyone look at this?
« Reply #24 on: September 25, 2019, 09:47:08 AM »
"Don't bother me with all this tech stuff, it just makes my head hurt.   I just want 5 lbs of solar, cheap."   ;)

These solar discussions nearly always end up like the tv commercial where the lady buys some cold cuts and a hearing aid at the supermarket deli counter, then ends up tossing the hearing aid in the trash cause it's junk.   Sometimes you just have to put a little of your own effort into a project, along with some solid technical assist, to get a useful result.

Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL