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gcrank1
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# Posted: 10 Feb 2021 11:28am - Edited by: gcrank1
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Ive a pair of 12v not in service (They do match my other 4 panels, 2 in series for 2 banks in parallel. I could tie them in with that array as another 2s for 3 banks of 2s in 3 parallel) but Im wondering about putting them together as a stand alone 'somewhat portable' 12v ground stand. This way I can optimize positioning in my compromised solar exposure and have the scc and battery being charged right at the array, rotating into use as needed.
Each panel:
102w
Rated about 18vmp
Peak about 21voc
Isc (iirc) 7.2a
Paired in parallel is peak (never realized) 21v/14a
Paired in series would be peak 42v/7a
I will have to get a new scc for either if I make em stand alone (my current MPPT can handle them if added).
So, should I go PWM (for parallel, 12v only) or a new, smaller cap. MPPT (for series @ 24v/to 12v thru scc)?
Objective: to get the best out of the array (isnt that what we all wish for, lol)
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Brettny
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# Posted: 10 Feb 2021 01:47pm
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I have 4 235w full sized pannels sitting in my shed right now. They also match my current pair in use. If my little roof would fit even one more pannel I would use it but it cant.
I say put then in your current array. Mppt is almost always the best choice. At least you can either use series or parallel with mppt.
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gcrank1
Member
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# Posted: 11 Feb 2021 06:14pm - Edited by: gcrank1
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Good point on the mppt scc can do both.
Has anybody here run a couple of panels like these on pwm and mppt so I can see real world amps numbers?
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Brettny
Member
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# Posted: 12 Feb 2021 08:25am
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I know on PWM anything over the charging voltage is lost. Mppt anything over the charging voltage is turned into more amps.
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paulz
Member
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# Posted: 12 Feb 2021 09:55am - Edited by: paulz
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I have a couple of spare panels at my city house (lots of sun) that I've done a little testing with, using both PWM and MPPT CCs. I don't have numbers, too many variables in batteries, hours of sun etc. but I have become convinced in the advantage of MPPT such that I would never spend any money on a PWM.
I also still have a couple of the 130w HF PWM systems hooked up at the cabin, neither of them seem to be doing much good, and they are advertised as low sun panels.
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ICC
Member
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# Posted: 12 Feb 2021 10:55am
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Quoting: gcrank1 Has anybody here run a couple of panels like these on pwm and mppt so I can see real world amps numbers?
No. But with a high voltage MPPT controller and enough panels, we have seen 10-12 watts from a full moon. You won't get that from PWM.
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Brettny
Member
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# Posted: 12 Feb 2021 11:18am
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I have a mppt also. I had about 1/2in of snow on the pannels last trip. I cleaned them off and gained 0.1a. I wont do that again. Not sure how PWM would react to snow on the pannels.
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gcrank1
Member
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# Posted: 12 Feb 2021 11:50am - Edited by: gcrank1
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Well, that cinches it. Just like NO more MSW inverters for me, NO more PWM cc, its all MPPT from here on out. 
My conclusion, my best use of these 2 panels is to series them for 24v and add to my array so it is the full 6 at 2s/3p on the Blue Sky 50 mppt scc.
That array and the powerhouse needs to become better located, right now my solar exposure is dead by noon. If I go east by 50ish yards it will be way better. It will also be more exposed, both to us and others looking up the driveway. Id like to just have a 'doghouse' for the scc, bat-bank and inverter but fear I would show up one day and find it all gone. I figure it would take a couple guys with a pickup truck less than an hour to disappear it all. My powerhouse/toolshed is a hard to move 8x12 ice shanty. With all the fancy stuff inside it is out of sight and pretty secure. Doesnt look bad either, homebuilt version of a 1930s travel trailer.
It would make a nice micro-cabin on its own; maybe someday.
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