12 or 24 volt solar with MPPT controller? - Dutchmen Owners

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Old 04-28-2016, 07:32 PM   #1
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12 or 24 volt solar with MPPT controller?

I appreciate all the input from these forums, I am not going to install a MPPT controller, Im trying to understand 12 verse 24 volts, we all know the coach runs on 12 volts, batteries output is 12 volts, but if I understand correctly if I run my solar panels in series to 24 volts that the MPPT controller will take the extra volts and convert those into AMPS at 12 volts? am I understanding this correctly?
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Old 04-28-2016, 09:09 PM   #2
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Yes you are.
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Old 04-28-2016, 09:19 PM   #3
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Originally Posted by DesertRat View Post
Yes you are.
Looks like I have a typo- I am installing a MPPT controller- so you would recommend sending 24 volts to the controller?
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Old 04-29-2016, 04:38 PM   #4
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Looks like I have a typo- I am installing a MPPT controller- so you would recommend sending 24 volts to the controller?
I think this ends up being and endless debate (series vs parallel) and since it sounds like you can do either, you might want to just experiment.

I think it depends on their orientation and potential shading situation. If you end up with shade on any of the panels in series, it may wipe out everything in that series. If they were in parallel, only the shaded panel would get wiped out and the unshaded ones would still be working.

Although some claim that a series panel string in poor light will still offer some usable voltage to the controller (> battery voltage) because the series string had more potential voltage available. So you're still getting usable output during poor sunlight conditions.

The series string will be limited by the lowest performer in the series so if your series panels are not all oriented the same way, the one contributing the least will bottleneck the current to the controller.

I think in ideal conditions and orientations it wouldn't matter if they were in series or parallel, both orientations would result in the same peak amps. But the higher voltage from in series allows for more efficient transfer and one can use thinner (less expensive) wires from the panels to the controller because they are transporting less amps. A series wiring setup can also be simpler than a parallel one.

12V panels in parallel will still provide "extra" voltage that the MPPT controller can convert to more amps, just like with 24V in series. But any extra voltage for the MPPT controller to convert to amps is only used during bulk charging. After that, it acts the same as PWM controller and controls current to the batteries to maintain the absorption or float voltage setpoint.

From a source that knows better than me. http://www.morningstarcorp.com/wp-co...March-2015.pdf
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Old 04-29-2016, 04:42 PM   #5
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Yes. Although it depends on their orientation and potential shading situation. If you end up with shade on any of the panels in series, it wipes out everything in that series. If they were in parallel, only the shaded panel would get wiped out and the unshaded ones would still be working. The series string will be limited by the lowest performer in the series so if your series panels are not all oriented the same way, the one contributing the least will bottleneck the current to the controller.
Great advice thank you, something to consider!
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Old 04-29-2016, 05:03 PM   #6
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Check this site out.
http://www.amazon.com/TRACER-3215RN-.../dp/B008KWPGAE

Go down to the questions & answers I think you will find all the info you need there..
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Old 04-29-2016, 05:33 PM   #7
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Great advice thank you, something to consider!
I vastly expanded on my first response since the time you quoted it, so you may want to look at it again. But in brief summary, either parallel or series will yield the same max current under ideal harvest conditions. So you'll need to base your decision on how the panels will be performing in less than ideal conditions.

Some reading about someone's actual observations of their setup in parallel and series.
Trailer Life Magazine Open Roads Forum: Tech Issues: Parallel or Series Solar?
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