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01-12-2016, 04:34 PM
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#21
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Member
Join Date: Nov 2015
Location: Denver
Posts: 82
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Quote:
Originally Posted by Cdash
See above, am I missing something? Won't you get all the power through PWM until you are charged?
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Here's a 12V 100W panel: 100 Watt 12 Volt Monocrystalline Solar Panel | Renogy Solar
Its 12V nominal, but actual specs are around 18.9V @ 5.3A. With PWM, that 5.3A would be maintained on the output side of the controller, but dialed down to only 12-14V as needed based on the charge state of the battery. Best case at 14.5V * 5.3A = 77W. That's the loss that Don was describing, I believe.
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2015 Ram 3500 SRW, 6.7L Cummins, Crew Cab, 4x4
2016 29BHDS
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01-12-2016, 06:22 PM
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#22
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Member
Join Date: Jul 2012
Posts: 92
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Yes you are right. I shouldn't post before coffee I guess. I still agree with Handy Bob that for small systems you get more bang for the buck buying an additional panel over paying for the MPPT. But that assumes you have room for the panel, etc. The most important part is to go into such an installation being educated and using quality components.
And then being on the road with solar is such a nice way to go. Yes the Honda generators are "quiet" but i have camped across the road from them and they get tiresome when they run all day.
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01-12-2016, 06:28 PM
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#23
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Senior Member
Join Date: Oct 2015
Location: Milford
Posts: 629
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Quote:
Originally Posted by JMC
Here's a 12V 100W panel: 100 Watt 12 Volt Monocrystalline Solar Panel | Renogy Solar
Its 12V nominal, but actual specs are around 18.9V @ 5.3A. With PWM, that 5.3A would be maintained on the output side of the controller, but dialed down to only 12-14V as needed based on the charge state of the battery. Best case at 14.5V * 5.3A = 77W. That's the loss that Don was describing, I believe.
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That helps. Didn't realize that the 12 volt panels went that high. Looked at the specs, but don't understand all the different numbers and what they are for.
What is the difference between Poly and Mono panels? Anything worth worrying about?
__________________
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch
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01-12-2016, 06:31 PM
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#24
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Senior Member
Join Date: Oct 2015
Location: Milford
Posts: 629
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Quote:
Originally Posted by waynem
And then being on the road with solar is such a nice way to go. Yes the Honda generators are "quiet" but i have camped across the road from them and they get tiresome when they run all day.
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That's what I'm thinking! Would still run a genny for air conditioning (wouldn't be around others for this) or microwave which would only be short stints.
Who knows, maybe I'll end up being able to run the microwave (bigger inverter) and leave the genny at home!
__________________
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch
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01-12-2016, 07:00 PM
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#25
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Site Team
Join Date: Nov 2012
Location: Clearwater, FL area
Posts: 5,196
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Which Solar Panel Type is Best?
Quote:
Originally Posted by Cdash
What is the difference between Poly and Mono panels? Anything worth worrying about?
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Everything you wanted to know about the different panels!
Which Solar Panel Type is Best?
Don
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01-12-2016, 07:27 PM
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#26
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Senior Member
Join Date: Oct 2015
Location: Milford
Posts: 629
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Quote:
Originally Posted by Mustang65
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Thank you, extremely helpful!
__________________
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch
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01-12-2016, 10:23 PM
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#27
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Senior Member
Join Date: Feb 2013
Location: Hot Sulphur Springs
Posts: 108
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Quote:
Originally Posted by JMC
Here's a 12V 100W panel: 100 Watt 12 Volt Monocrystalline Solar Panel | Renogy Solar
Its 12V nominal, but actual specs are around 18.9V @ 5.3A. With PWM, that 5.3A would be maintained on the output side of the controller, but dialed down to only 12-14V as needed based on the charge state of the battery. Best case at 14.5V * 5.3A = 77W. That's the loss that Don was describing, I believe.
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Ignorance here so...
Why does this matter? Aren't we just wanting to put Amps back into the battery? If the Amps don't change, only wattage, what are we PWM users loosing?
Thanks in advance,
Jeremy
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01-13-2016, 07:17 AM
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#28
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Member
Join Date: Aug 2013
Location: Edmonton
Posts: 43
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There is a good channel on YouTube that answers a lot of the questions asked here.
https://www.youtube.com/user/AltEStore
Once you have the knowledge and match the system to your battery capacity, you should get many years of low maintenance performance out of your system.
__________________
2012 Jayflight 28 BHS
2014 F150, 5.0 L, 3.55 axle
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01-13-2016, 08:18 AM
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#29
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Member
Join Date: Aug 2013
Location: Edmonton
Posts: 43
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Ignorance here so...
Why does this matter? Aren't we just wanting to put Amps back into the battery? If the Amps don't change, only wattage, what are we PWM users loosing?
Thanks in advance,
Jeremy
Pulse Width Modulation works by turning the power applied off and on. During the off cycle, no power is received by the battery. As the battery approaches about 90% charge, the controller spends more and more time in the off part of the cycle. What you get is high amperage pulses followed by rest as the battery voltage returns to the controller voltage setpoint. One of the side effects to this is increased water loss due to gassing in the battery.
MPPT feeds a steady amperage to the battery. This amperage decreases as the battery approaches full charge. The output is a steady trickle charge, charging the battery to full saturation quite efficiently. Charging this way has very little water loss as gassing is kept to a minimum.
The other advantage is performance in low light conditions. Because PWM uses lower voltage panels, higher solar flux rates are needed to bring the panel voltage above battery voltage so charging can begin. Because MPPT can accept much higher input voltages, you can take advantage of higher voltage panels. Example, half output on a 18 volt panel = 9V, no charging, half output on a 36 volt panel = 18V, battery charges.
My personal experience using a 24 volt (36V open circuit) panel show that the system starts charging as soon as it gets light out, even before sunrise, and even on cloudy days still charges at a reduced rate.
__________________
2012 Jayflight 28 BHS
2014 F150, 5.0 L, 3.55 axle
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01-13-2016, 08:29 AM
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#30
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Member
Join Date: Jun 2015
Location: Columbus
Posts: 55
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By the end of the day everything needs to be set based on your usage.
Do you use toasters? Do you fry eggs on electric appliances? Does your wife dry her hair with a blower?
If you intend to run a fridge/freezer, I doubt you can make it with less than 400W...
I have a boat with a 10w solar panel, morningstar charging controller and AGM Battery. My set up work for me because we only use the boat during weekends, all my lights are LED's and we only use the inverter eventually for light uses like a small blender, a small vaccum cleaner and the charging of the I-stuff. So the 10W can keep the battery 100% most of the time. The battery goes to 50% by the end of a two day stay.
I'm also following liveaboards for years now and it seems that the cheapest route is Trojan Golf Cart Batteires linked to at least 200W of solar and one small charge controller for each solar panel (that seems to be the more trouble free set up).
Trojans are heavy but reliable if you take care of the water level in them.
Again, the amount of Solar will depend of your usage.
__________________
Ricardo & Luciana
For a person may labor with wisdom, knowledge and skill, and then they must leave all they own to another who has not toiled for it. This too is meaningless ... Ecclesiastes 2:21
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01-13-2016, 08:40 AM
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#31
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Senior Member
Join Date: Sep 2010
Location: PNW
Posts: 5,195
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I've learned a lot from this thread. Thanks to all of you who've posted!
__________________
Bill
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH
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01-13-2016, 08:41 AM
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#32
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Site Team
Join Date: Nov 2012
Location: Clearwater, FL area
Posts: 5,196
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Quote:
Originally Posted by jaycojls
Ignorance here so...
Why does this matter? Aren't we just wanting to put Amps back into the battery? If the Amps don't change, only wattage, what are we PWM users loosing?
Thanks in advance,
Jeremy
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Jeremy,
There is nothing wrong with PWM controllers... I was just clarifying what the differences are between the two technologies.
The main intent in forums is to answer other members questions. Because one type of technology outperforms another does not mean that it should not be purchased, or over looked, but if a member may be looking for utilizing his purchases to their fullest potential (serious dry-camping...) they should be made aware of the differences. Yes, you can add more panels to make up for the differences between the 2 technologies, and down the road (no pun intended) you can always switch to an MPPT if you are out of space.
I just look at the question and share information that I have. It is still up to the individual member to decide which one meets their personal needs.
I hope we may have answered the questions raised in this thread. If not, let the members know so that they can be addressed. Like I said there is nothing wrong with PWM controllers, they fill their nitch perfectly, as do MPPT controllers.
I just wanted to make individuals aware of the differences and the effect they have on performance..
Don
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01-13-2016, 09:06 AM
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#33
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Member
Join Date: Aug 2013
Location: Edmonton
Posts: 43
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Well said! X2
Some other areas on the web PWM vs MPPT borders on religon, to the point I was reluctant to post here. No flames! Great!
__________________
2012 Jayflight 28 BHS
2014 F150, 5.0 L, 3.55 axle
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01-13-2016, 09:30 AM
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#34
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Senior Member
Join Date: Feb 2013
Location: Hot Sulphur Springs
Posts: 108
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Quote:
Originally Posted by Mustang65
Jeremy,
There is nothing wrong with PWM controllers... I was just clarifying what the differences are between the two technologies.
The main intent in forums is to answer other members questions. Because one type of technology outperforms another does not mean that it should not be purchased, or over looked, but if a member may be looking for utilizing his purchases to their fullest potential (serious dry-camping...) they should be made aware of the differences. Yes, you can add more panels to make up for the differences between the 2 technologies, and down the road (no pun intended) you can always switch to an MPPT if you are out of space.
I just look at the question and share information that I have. It is still up to the individual member to decide which one meets their personal needs.
I hope we may have answered the questions raised in this thread. If not, let the members know so that they can be addressed. Like I said there is nothing wrong with PWM controllers, they fill their nitch perfectly, as do MPPT controllers.
I just wanted to make individuals aware of the differences and the effect they have on performance..
Don
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Actually, I was wondering if my assumption, hence the ignorance part, was correct?
So with the PWM controller I am still getting the same amps just loosing watts in the controller, correct?
With an MPPT controller, it can convert any voltage above the charging voltage to amps, correct?
Sorry for the confusion, and was really wondering if loosing that wattage really mattered if we were still getting max stated amps from the panel. So does it matter? I'm assuming not, and is that wattage that is lost how the MPPT controller creates it's additional amps? Just trying to learn... 😊
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01-13-2016, 09:49 AM
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#35
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Senior Member
Join Date: Aug 2015
Location: Albany, OR
Posts: 692
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Quote:
Originally Posted by jaycojls
Actually, I was wondering if my assumption, hence the ignorance part, was correct?
So with the PWM controller I am still getting the same amps just loosing watts in the controller, correct?
With an MPPT controller, it can convert any voltage above the charging voltage to amps, correct?
Sorry for the confusion, and was really wondering if loosing that wattage really mattered if we were still getting max stated amps from the panel. So does it matter? I'm assuming not, and is that wattage that is lost how the MPPT controller creates it's additional amps? Just trying to learn...
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The confusion you are having is that you are assuming that amps do not change with an MPPT controller. In fact, amps do change. You can think of an MPPT controller as a "matching" device. It allows the panel to operate at its ideal voltage and then converts that to a voltage that is appropriate for the battery. When it makes this conversion more current (amps) are available for charging the battery. The concept is somewhat like a stepdown transformer used in AC power.
Assuming V = Voltage and I = Amps.
The equation for an MPPT controller is: Vpanel / Vbattery * Ipanel
So if you have a 24V panel with a max current of 10A.
24V / 12V * 10A = 20A delivered to battery.
With a PWM controller the output is simply Ipanel or 10A in this case.
Of course this is an over-simplified example, but you get the idea.
__________________
2015 Jayco 27RLS
2015 Ford F250 6.7PSD
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01-13-2016, 11:22 AM
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#36
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Site Team
Join Date: Nov 2012
Location: Clearwater, FL area
Posts: 5,196
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Quote:
Originally Posted by jaycojls
Sorry for the confusion, and was really wondering if loosing that wattage really mattered if we were still getting max stated amps from the panel. So does it matter? 😊
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The best way to answer this is by my asking if the PWM system meets the needs of the system owner? If it does then it really does not matter. If it does not meet the needs, then they would have to decide which way they wanted to proceed.
Don
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01-13-2016, 11:31 AM
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#37
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Senior Member
Join Date: Feb 2013
Location: Hot Sulphur Springs
Posts: 108
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DanNJanice, Don thank you kindly.
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01-13-2016, 11:58 AM
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#38
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Member
Join Date: Nov 2015
Location: Denver
Posts: 82
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Quote:
Originally Posted by jaycojls
Actually, I was wondering if my assumption, hence the ignorance part, was correct?
So with the PWM controller I am still getting the same amps just loosing watts in the controller, correct?
With an MPPT controller, it can convert any voltage above the charging voltage to amps, correct?
Sorry for the confusion, and was really wondering if loosing that wattage really mattered if we were still getting max stated amps from the panel. So does it matter? I'm assuming not, and is that wattage that is lost how the MPPT controller creates it's additional amps? Just trying to learn... 😊
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I'm learning this stuff as i go, too. But i think there's more to it than saying that we're trying to put amps in to the battery. We're trying to put electrons into the battery. And the way we measure that is a certain number of amps at a given voltage.... A * V = watts.
For example... putting 5A into a 12V battery is less power than putting 5A into a 48V battery. The amps alone aren't the full story. Both are 5A but since the voltages are different, the amount of power is very different.
__________________
2015 Ram 3500 SRW, 6.7L Cummins, Crew Cab, 4x4
2016 29BHDS
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01-14-2016, 02:31 PM
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#39
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Senior Member
Join Date: Oct 2015
Location: Milford
Posts: 629
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Quote:
The other advantage is performance in low light conditions. Because PWM uses lower voltage panels, higher solar flux rates are needed to bring the panel voltage above battery voltage so charging can begin. Because MPPT can accept much higher input voltages, you can take advantage of higher voltage panels. Example, half output on a 18 volt panel = 9V, no charging, half output on a 36 volt panel = 18V, battery charges.
My personal experience using a 24 volt (36V open circuit) panel show that the system starts charging as soon as it gets light out, even before sunrise, and even on cloudy days still charges at a reduced rate.
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This brings up another one: Shade
Is there any difference between shade in a panel from a vent cover, antenna, etc. and shade from being parked near or under trees, or shade from clouds?
__________________
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch
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01-18-2016, 08:56 AM
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#40
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Member
Join Date: Aug 2013
Location: Edmonton
Posts: 43
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A perfect example of this was last Friday, Jan 15. I had to go out to the trailer/ job site, weather was light snow, about 2" covering the panel, overcast skies. Panel voltage 26.3V, battery 13.4V, charging .63 amps. As I said in a previous post, I'm at 53 degrees latitude, so our solar flux levels are very low at this time of year. Not enough power to use the trailer at this time of year, but more than ample to maintain battery condition without having to disconnect fuses or disconnecting the batteries.
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2012 Jayflight 28 BHS
2014 F150, 5.0 L, 3.55 axle
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