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  • Mike90250
    replied
    When you get panels out of good alignment (flat on a roof is usually poor alignment) you get a pretty significant reduction of output - something about 50% less. That's why solar on RV's a boats is not always a great investment

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  • RiP-HS-
    replied
    Thank You Mike!

    I took to Amazon and ordered the 2-way combiners and will give it a shot as soon as they arrive. Here is a photo of what I was getting from the charge controller screen today. Well, when trying to upload it keeps telling me invalid file type.

    At Noon it was reading - 35.6v, 488w, 20.2a.

    Currently the panels are laying flat (not yet attached) on a unistrut frame on the roof of a shipping container. I may have to experiment with trying to tilt the frame to get a little more juice. I was hoping laying flat would be good enough.

    Thanks Again!

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  • Mike90250
    replied
    ( well the table looked OK in the draft) sorry

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  • Mike90250
    replied
    first, you only need 70V for the controller to operate well on a 24V battery, as you go higher in voltage, your conversion losses increase.

    second, I would wire like panels in series. - ----325---325---- +
    and then parallel the two series strings

    [TABLE="border: 1, cellpadding: 1, width: 500"]
    [TR]
    [TD] - ----325---325---- + [/TD]
    [/TR]
    [TR]
    [TD] - --------| |------------ +[/TD]
    [/TR]
    [TR]
    [TD] - ----365---365---- + [/TD]
    [/TR]
    [/TABLE]

    This will lower your total PV voltage to about 75V but allow full amps of about 18A into the controller 1,350watts (in
    an ideal world) But since we live in real life, I'd take losses of about 20% , for well aimed panels, and expect to see
    about 1,000watts on a excellent day. 4 hours of that and you have 4kwh harvest under the best conditions. Average conditions,
    I'd expect 800w harvest, which at 28V charging, would be 28Amps
    I would use a pair of 100V rated DC breakers 15A to be able to switch each string off and on to diagnose any issues.
    I would use a 60A breaker (and 60a rated wire) on the output to the battery, which will allow you to add more PV before needing to change breaker or wiring.
    For the PV wiring, I would use 10ga if the runs are not really long, but if they were over 30' one way, I'd use 8ga wire to reduce losses

    I would not put all 4 panels in series just because the controller could handle it. It will cause the 2 smaller panels to throttle the amps and you will never be able to troubleshoot without taking all 4 panels apart.

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  • RiP-HS-
    started a topic Parallel or Series?

    Parallel or Series?

    Hello Everyone!

    Quick question... I have just purchased a Midnite 200 Classic and two different sets of two panels. Currently I have them wire in parallel but I feel like it's not as efficient as I feel it should be. I'm new to the Midnite and my install looks like crap right now - just getting it all running and I will clean it all up. Currently, I want it to run a small window unit all day long.
    I have 8 6v, 210AH golf cart Batteries (wired 24v), Midnite Classic 200, Aims 2000w inverter/charger, 2-325w and 2-365w panels.
    ​​​​​​Please see attached picture for panel specs.

    Does the charge controller prefer amps or voltage? I also have another cheaper but very commonly used Chinese MPPT charge controller. Would it be worth setting up the separate charge controller to keep the two different style panels separate?

    Thank You All!
    Attached Files
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