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Author Topic: Adding Solar Panels  (Read 505 times)

keith c

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Adding Solar Panels
« on: July 17, 2017, 03:32:54 PM »
At present, I have 2 160Watt solar panels and am thinking of adding 1 more panel.  The 2 panels I have now are wired in parallel.  I have a 40 amp MPPT charge controller, so another solar panel shouldn't be an issue.  Can I add a different wattage solar panel and wire it in series (eg 200 watt panel)? 
Keith C
2017 Ford F150 3.5L Ecoboost w/ Max Trailer Tow
2013 Jayco Eagle 304BHS
320 Watts of Solar
Michigan

Paul & Ann

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Re: Adding Solar Panels
« Reply #1 on: July 17, 2017, 03:57:26 PM »
I believe adding another solar panel in series will be ok if the voltage of the 200 watt panel is close to the voltage of the 160 watt panels, but the output of the 200 watt panel will be limited to 160 watts.
Paul & Ann  Iowa
2005 Winnebago Voyage 38J
http://stoughrvadventure.blogspot.com/

keith c

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Re: Adding Solar Panels
« Reply #2 on: July 18, 2017, 06:35:20 AM »
Thanks Paul & Ann.  Why would I be limited by the 160 watt panel?  I would keep the 2 160Watt panels wired in parallel and then add the 200 watt panel by wiring that one in series.  Wouldn't the voltage be additive to what the 2 160 watt panels are producing?  Thanks for your help.
Keith C
2017 Ford F150 3.5L Ecoboost w/ Max Trailer Tow
2013 Jayco Eagle 304BHS
320 Watts of Solar
Michigan

Paul & Ann

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Re: Adding Solar Panels
« Reply #3 on: July 18, 2017, 08:47:48 AM »
I will have to think about that for a minute.  I thought you were going to put all three panels in series.

Here is some information on series and parallel connections of solar panels.

http://solarpanelsvenue.com/mixing-solar-panels/
« Last Edit: July 18, 2017, 09:00:44 AM by Paul & Ann »
Paul & Ann  Iowa
2005 Winnebago Voyage 38J
http://stoughrvadventure.blogspot.com/

Kevin Means

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Re: Adding Solar Panels
« Reply #4 on: July 18, 2017, 11:35:12 AM »
I believe Paul is giving you good information. I did a lot of reading, and talked with some very solar- knowledgeable people before installing our system, and learned that the output of individual solar panels should be as close to the same as possible, whether they're wired together in series or parallel. That isn't to say they won't work if they're not the same, but the lower output panel(s) will, essentially, reduce the output of the higher output panel to that of the lower output panels (Did I say that clearly?)

Basically, using panels with different outputs means you'd be wasting, roof space, power and, perhaps, money.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

kdbgoat

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Re: Adding Solar Panels
« Reply #5 on: July 18, 2017, 11:51:15 AM »
I know Handy Bob runs (3) 75 watt, and (1) 120 watt on his rig with no issues.

https://handybobsolar.wordpress.com/about/
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

Kevin Means

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Re: Adding Solar Panels
« Reply #6 on: July 18, 2017, 12:12:08 PM »
...and Bob Shearer (HandyBob) was the one who told me to use panels with the same output. I paid Bob a stipend to advise me on the installation of our system. Like I said, an array consisting of panels with different outputs will work, you just won't realize all the power that the panels are capable of putting out.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

keith c

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Re: Adding Solar Panels
« Reply #7 on: July 18, 2017, 12:38:24 PM »
Kevin, Paul, thanks for the information.  By adding the 3rd one in series, I was trying to reduce line losses by increasing the voltage ilo current.  Right now, I have 8 gage wire for the 2 solar panels hooked up in parallel.  I'll do more reading before adding anything. 
Keith C
2017 Ford F150 3.5L Ecoboost w/ Max Trailer Tow
2013 Jayco Eagle 304BHS
320 Watts of Solar
Michigan

kdbgoat

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Re: Adding Solar Panels
« Reply #8 on: July 18, 2017, 01:39:43 PM »
...and Bob Shearer (HandyBob) was the one who told me to use panels with the same output. I paid Bob a stipend to advise me on the installation of our system. Like I said, an array consisting of panels with different outputs will work, you just won't realize all the power that the panels are capable of putting out.

Kev

I believe Bob has his wired in parallel, not series. If I remember correctly, he did advise against wiring different size panels in series. It's been a long time I've visited his site except to copy the URL, so I could be wrong there too.
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

AStravelers

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Re: Adding Solar Panels
« Reply #9 on: July 18, 2017, 06:30:53 PM »
Just like wiring batteries in series or parallel, they must match.

If wiring solar panels in parallel, they must match in voltage.  If wiring in series they must match in amperage.

You can think of your pair of 160 watt panels, wired in parallel, as one 320 watt panel.  Now when you wire in your 200 watt panel is series with the 320watt panel you have a large mismatch of amperage.  I don't know if any damage would occur, but I am pretty sure you will wind up with a pair of 200watt panels instead of a 320 watt and a 200 watt.

Think of wiring a 100AH battery in series with a 200AH battery.

« Last Edit: July 18, 2017, 06:35:23 PM by AStravelers »
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

AStravelers

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Re: Adding Solar Panels
« Reply #10 on: July 18, 2017, 08:24:33 PM »
Finally found a reference to quote about matching panels when wiring parallel or series.  http://www.alternative-energy-tutorials.com/energy-articles/connecting-solar-panels-together.html

Don't ask me to describe the physics behind the limiting factors.  I just remember reading references to the problems with mis-matching the voltages or currents over the last 10 years or so.
« Last Edit: July 18, 2017, 08:34:30 PM by AStravelers »
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

butchiiii

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Re: Adding Solar Panels
« Reply #11 on: July 19, 2017, 12:19:46 AM »
Finally found a reference to quote about matching panels when wiring parallel or series.  http://www.alternative-energy-tutorials.com/energy-articles/connecting-solar-panels-together.html

Don't ask me to describe the physics behind the limiting factors.  I just remember reading references to the problems with mis-matching the voltages or currents over the last 10 years or so.

Excellent article.
Thanks
Butch & Joanna
Ram 2015 Reg Cab 1500
2015 Keystone Passport 2890RL

keith c

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Re: Adding Solar Panels
« Reply #12 on: July 19, 2017, 02:58:51 PM »
Al, thanks for the article.  I also read a lot of what HandyBob had written.  Very helpful.  If I do decide to add more panels, I'll try to match the new panel with my existing panels' voltage and amperage.
Keith C
2017 Ford F150 3.5L Ecoboost w/ Max Trailer Tow
2013 Jayco Eagle 304BHS
320 Watts of Solar
Michigan

kdbgoat

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Re: Adding Solar Panels
« Reply #13 on: July 19, 2017, 07:11:40 PM »
Some good reading here also:

http://www.jackdanmayer.com

I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

supermanotorious

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Re: Adding Solar Panels
« Reply #14 on: July 20, 2017, 08:58:00 AM »
Where is the chart that shows voltage drop for charge controller wire size in 12V, 24V, 36V, and 48V? I found it yesterday, can't find it today
Home is Phoenix, AZ
2008 Skyline Freestyle M-240 Way-Lite
2003 Harley Davidson Dyna FXDX
2003 Chevrolet Avalanche 2500 8.1L 496ci 4x4
1994 Four Winns Freedom
various quads, off-road gokarts, mini bikes
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Kevin Means

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Re: Adding Solar Panels
« Reply #15 on: July 20, 2017, 11:47:57 AM »
Here's one of several that are online in which you can enter the parameters. http://www.rapidtables.com/calc/wire/voltage-drop-calculator.htm

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

 

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