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04-08-2018, 09:47 AM
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#1
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Junior Member
Join Date: Apr 2017
Location: Riverside Wa.
Posts: 8
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Solar Panel Mixing?
Hello,
My 2005 Fleetwood Bounder came with two 65w poly solar panels and a Blue Sky 30 PWM charge controller. the previous owners had two additional solar panels on top that they removed when they traded it in.
My question is that I thought the current panels where 100w so I ordered two additional 100w panels to give me 400w of solar.
So now I have two 65w panels already installed, can I simply install the two 100w panels and hook up? Or will the smaller panels pull the 1000w ones down in power? And I can't tell which left behind wires are positive or negative on top of the coach without pulling the wires all out and starting over.
Ken
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04-08-2018, 09:51 AM
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#2
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Registered User
Join Date: Aug 2014
Location: western NC mountains!
Posts: 4,106
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as long as a panel is the 12v variety, I assume the same as came with your coach, you're good to go
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04-08-2018, 10:11 AM
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#3
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Senior Member
Join Date: Aug 2017
Location: Syracuse Ut.
Posts: 692
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From what I've seen playing around with solar you can get away with quite a bit of variance when using a PWM controller and parallel connected solar panels. Ideally you want to keep the panel voltages as close as possible, but in practice, different voltages output doesn't seem to have as much of a negative impact as might be expected. Using a PWM controller and different wattage panels doesn't have a negative impact at all and your total current will be all the outputs added up. My experience is that MPPT controllers tend to be a little less tolerant of mixing panels in parallel and if one is significantly lower in output you just basically tend to loose the output of that panel completely.
__________________
2016 Bighorn 3270RS, 2015 Ram 3500 CTD/ASIN
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04-08-2018, 11:34 AM
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#4
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Junior Member
Join Date: Apr 2017
Location: Riverside Wa.
Posts: 8
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Quote:
Originally Posted by MisterT
as long as a panel is the 12v variety, I assume the same as came with your coach, you're good to go
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Thanks, yes its all 12v
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04-08-2018, 11:36 AM
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#5
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Junior Member
Join Date: Apr 2017
Location: Riverside Wa.
Posts: 8
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Quote:
Originally Posted by Searching_Ut
From what I've seen playing around with solar you can get away with quite a bit of variance when using a PWM controller and parallel connected solar panels. Ideally you want to keep the panel voltages as close as possible, but in practice, different voltages output doesn't seem to have as much of a negative impact as might be expected. Using a PWM controller and different wattage panels doesn't have a negative impact at all and your total current will be all the outputs added up. My experience is that MPPT controllers tend to be a little less tolerant of mixing panels in parallel and if one is significantly lower in output you just basically tend to loose the output of that panel completely.
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Thanks for the help, I thought that somewhere it was mppt was better then the pwm but I probably had it backwards.
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04-08-2018, 12:18 PM
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#6
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Senior Member
Join Date: Aug 2017
Location: Syracuse Ut.
Posts: 692
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Better is one of those subjective things where it depends. Especially with high voltage panels, mppt controllers can harvest more energy from your panels. They are also the only option for high voltage systems be it high voltage panels or hooking your panels in series. They do however sometimes have more issues in figuring out setpoints if you have a mismatch in parallel mounted panels. During bulk charging pwm controllers basically just directly connect the panels to the batteries allowing the max current the panel can produce at the batteries voltage. With mismatched panels this can be advantage whereas with a more balanced system where an mppt controller can do it’s magic more effectively, the mppt controller will often harvest 10 percent or so more energy.
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2016 Bighorn 3270RS, 2015 Ram 3500 CTD/ASIN
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04-08-2018, 12:21 PM
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#7
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Senior Member
Join Date: May 2017
Location: Itinerant
Posts: 755
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It's not as simple as saying one is better than the other more like one works better with a particular size system.
__________________
2010 Cameo F34CK3, 500ah GBS LFP, 1280w solar, Magnum PT100 SCC & 3012 hybrid inverter/ charger, Installed 4/2016 been on 24/7/365, daily 35-45% DOD 2,656+ partial cycles.
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04-08-2018, 03:43 PM
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#8
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Senior Member
Join Date: Dec 2016
Posts: 149
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I have a 12v 400w watt system. With a 100-30 mppt controller. If i expand my system can i use a 100-15 controller in addition to the 100 30? Im assuming if i only run the additional 2 panels off of it it would be fine..
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04-08-2018, 04:24 PM
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#9
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Senior Member
Monaco Owners Club National RV Owners Club Workhorse Chassis Owner
Join Date: Dec 2013
Location: St. Charles MO
Posts: 4,920
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Cover you panels with a blanket. Check continuity with multi meter for figuring out your wires.
__________________
2002 Monaco Windsor 40PST 2019 Equinox 1.5L, Blue OX Aventa LX tow bar, Roadmaster EZ5 baseplate, SMI Stay-In-Play Duo, TireSafeGuard TPMS
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04-08-2018, 04:41 PM
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#10
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Senior Member
Join Date: Jan 2015
Location: Prescott, Arizona
Posts: 3,564
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Mixing panels would be a good question for Handy Bob: https://handybobsolar.wordpress.com/
__________________
'04 Newmar MADP, 1100w of solar, Rubicon toad
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04-22-2018, 04:10 PM
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#11
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Senior Member
Join Date: Dec 2014
Location: Warren, MI
Posts: 268
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Quote:
Originally Posted by mikeypj
I have a 12v 400w watt system. With a 100-30 mppt controller. If i expand my system can i use a 100-15 controller in addition to the 100 30? Im assuming if i only run the additional 2 panels off of it it would be fine..
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Yes you can, if you make sure that both controllers have the same charging settings.
__________________
Tom - KK8M -Warren, Michigan
MI Licensed Electrician, ISA Level 2 Certified I&C Tech, UL Certified PV Installer, Organic "Olla Irrigation" Gardener and bona fide Schlepper
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