Bill j. Posted January 1, 2015 Report Share Posted January 1, 2015 This is probably for Jack, but all thoughts are appreciated. I have 2 100W panels on top now and have just received one 140 W and 1 160 W panel. Any reasons why I should not parallel them all together? Controller is a Morning star 30 A. Happy New Year All. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
earlvillestu Posted January 1, 2015 Report Share Posted January 1, 2015 If the Vmp ratings are close (within about 5 percent) , and the combined Imp ratings don't exceed the capacity of your controller by more than about 20%, then you should be okay. With more than 2 parallel strings, each string should be separately fused. Link to comment Share on other sites More sharing options...
Bill j. Posted January 1, 2015 Author Report Share Posted January 1, 2015 Vmpp looks to be 18VDC and Impp will be no more than approx. 25 A for the total circuit. I doubt that I will ever see that. The Panels are mounted flat. More realistic output will probably be in the neighborhood of 18A. I'm too cheap to trade out the old panels (10 yrs old) for up to date panels. That's why I was wondering about the mixed wattage panels. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
Yarome Posted January 1, 2015 Report Share Posted January 1, 2015 Any reasons why I should not parallel them all together? None whatsoever.. You're golden. Kick back and enjoy. Link to comment Share on other sites More sharing options...
Jack Mayer Posted January 2, 2015 Report Share Posted January 2, 2015 Bill, if these are low voltage panels then you will not have an issue, as others have said. I cover both low voltage and high voltage situations like this on my website, along with some examples of each. The effect can be surprising, depending on the panel specs. It is in the "Wiring" section - Solar Array Wiring Considerations Jack & Danielle Mayer #60376 Lifetime Member Living on the road since 2000PLEASE no PM's. Email me. jackdanmayer AT gmail 2016 DRV Houston 44' 5er (we still have it) 2022 New Horizons 43' 5er 2016 Itasca 27N 28' motorhome 2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU No truck at the moment - we use one of our demo units 2016 smart Passion, piggyback on the truck -------------------------------------------------------------------------See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar powerwww.jackdanmayer.com Principal in RVH Lifestyles. RVH-Lifestyles.com Link to comment Share on other sites More sharing options...
Bill j. Posted January 2, 2015 Author Report Share Posted January 2, 2015 Thanks for the encouragement Yarome. Thanks Jack, I'll have a look at Jack's site today. Yes, they are 12VDC panels. Reason for the upgrade is upcoming annual trip to Quartzsite and recent refrig replacement with a residential refrigerator. Two hundred watts of solar will not be enough for an extended stay. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
oldjohnt Posted January 3, 2015 Report Share Posted January 3, 2015 Bill, FWIW here's one more take from an old retired engineer. In a nutshell, YES it will work, NO its not how some purist or a seller of panels might recommend lol. Looks like a total of 500 watts (if I understood your post) which under ideal bright sun direct overhead may crowd your 30 amp charge controller but I don't see that happening to much or too often based on my roof top flat mounted panel experience. If I were in your shoes and already had those panels Id probably hook them all up in parallel and not worry, even though my engineers preference would be to use a set of matched panels and Id consider some sort of series/parallel arrangement to run 24 volts down instead of 12. GO FOR IT is what Id do, if you were starting from scratch you might do differently. PS I will have the same question for myself next spring when I plan to add another 200 or 240 watts to my existing 200, I may go with 24 volts down to reduce current and voltage drop. John T Left Bushnell SKP later to Zolfo Springs SKP Link to comment Share on other sites More sharing options...
Jack Mayer Posted January 3, 2015 Report Share Posted January 3, 2015 Nothing "purist" going on here. It is simply physics. Stray too far away from what is "correct" and you will pay the price. But there is slop room, for sure. Jack & Danielle Mayer #60376 Lifetime Member Living on the road since 2000PLEASE no PM's. Email me. jackdanmayer AT gmail 2016 DRV Houston 44' 5er (we still have it) 2022 New Horizons 43' 5er 2016 Itasca 27N 28' motorhome 2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU No truck at the moment - we use one of our demo units 2016 smart Passion, piggyback on the truck -------------------------------------------------------------------------See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar powerwww.jackdanmayer.com Principal in RVH Lifestyles. RVH-Lifestyles.com Link to comment Share on other sites More sharing options...
Bill j. Posted January 3, 2015 Author Report Share Posted January 3, 2015 Thanks John, Soon as it warms up here I will go ahead with the install as planned. I'm sure I will never see 30A from this system. I'll be very happy with an occasional 25A. No system is perfect. We use to say "close enough for government work" but these days government work leaves a bad taste in my mouth. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
oldjohnt Posted January 3, 2015 Report Share Posted January 3, 2015 "close enough for government work" HEY that's where I practiced engineering most of my career lol The government had the money so we usually did things pretty well "right" as the taxpayers (that's you and I ) funded us !!!!!!!!!!!!!!!! John T Link to comment Share on other sites More sharing options...
reed and elaine Posted January 3, 2015 Report Share Posted January 3, 2015 oldjohnt x2 with your assessment on "government work". I spent my career as a physicist in Army Research Labs. Invariably I found that government science and engineering was far superior to the work done by the major contractors, and were far more cost effective. Link to comment Share on other sites More sharing options...
Bill j. Posted January 3, 2015 Author Report Share Posted January 3, 2015 My...My. Think I found some thin skin. Must be the time of year. Let's see, I spent 20 years in the USAF, last several years as an technical inspector or contract monitor. Then spent the next 20 years as a government contractor for the US Army. Been on both side of the fence. I've seen good and bad. I have my opinions and others have theirs. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
Bill j. Posted January 3, 2015 Author Report Share Posted January 3, 2015 To get back on topic, Jack, do you think those buses on that end solar panel will be challenged by the possible 20A to 25A passing through with all panels in parallel? I think I will change out the wiring to 6 gauge though. Gonna spend more roof time than I figured. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
Jack Mayer Posted January 3, 2015 Report Share Posted January 3, 2015 You have to make sure that any components you use to fabricate a solution can take the power. That is why doing a bunch of daisy chained panels is a bad idea.....the components are not rated for the power being fed downstream over the last few panels. It is much better to do home-runs back to a combiner for that reason. Jack & Danielle Mayer #60376 Lifetime Member Living on the road since 2000PLEASE no PM's. Email me. jackdanmayer AT gmail 2016 DRV Houston 44' 5er (we still have it) 2022 New Horizons 43' 5er 2016 Itasca 27N 28' motorhome 2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU No truck at the moment - we use one of our demo units 2016 smart Passion, piggyback on the truck -------------------------------------------------------------------------See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar powerwww.jackdanmayer.com Principal in RVH Lifestyles. RVH-Lifestyles.com Link to comment Share on other sites More sharing options...
Bill j. Posted January 3, 2015 Author Report Share Posted January 3, 2015 Thanks Jack, Now is the time to do this, warm weather coming in Wed. Just have to put it all together. Bill j. with one very understanding wife, 2004 34ft. Meridian Itasca DP, 2013 honda CRV, one comanding CAT!! SKP # 63321 Link to comment Share on other sites More sharing options...
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