What Specification matters most when buying a solar panel for a 12volt system?

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lightsky
lightsky Registered Users Posts: 13 ✭✭
edited December 2020 in General Solar Power Topics #1
What's your solar panel buying guide?
My current setup: 12v 1.5KVA low frequency inverter, 220Ah tubular battery, I keep all my load below 300watt.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #2
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    Hi lightsky,

    The design of the system has a large influence on the PVs that are used.

    System design follows from the purpose of the system,  the loads the system needs to supply,  when those loads occur,  etc.  This information would dictate weather batteries are needed,   their  capacity,  type,  and what any batteries would need for proper charging.

    From the above,   the amount of PV needed.   This would tell one about what is needed,  to keep any battery charging devices "happy",   etc.

    System design is a bit of an iterative process  --   make a little change here,   may need a few other things,  elsewhere to be changed,   which may require some other thing/s to be tweaked,   and so on.

    Having a carefully-considered system design,  is essential,     BEFORE     buying any system components.

    SO,   it all depends   ...   FWIW,  Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #3
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    Vic said:

    Having a carefully-considered system design,  is essential,     BEFORE     buying any system components.
    This!!! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Way too many variables t just say one thing. 

    If you are setting up a small system a more expensive 12 volt nominal that would work with a cheap PWM charge controller might be best.

    Trying for a mobile array on a tiny home or RV? or some pole mounted systems or even a small roof. Then the panels efficiency might be primary (How well the panel converts available sunlight to wattage) 

    Setting up a free standing array in a field, best price per watt, excluding poor life time panels or toxic materials.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • lightsky
    lightsky Registered Users Posts: 13 ✭✭
    #4
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    Vic said:
    Hi lightsky,

    The design of the system has a large influence on the PVs that are used.

    System design follows from the purpose of the system,  the loads the system needs to supply,  when those loads occur,  etc.  This information would dictate weather batteries are needed,   their  capacity,  type,  and what any batteries would need for proper charging.

    From the above,   the amount of PV needed.   This would tell one about what is needed,  to keep any battery charging devices "happy",   etc.

    System design is a bit of an iterative process  --   make a little change here,   may need a few other things,  elsewhere to be changed,   which may require some other thing/s to be tweaked,   and so on.

    Having a carefully-considered system design,  is essential,     BEFORE     buying any system components.

    SO,   it all depends   ...   FWIW,  Vic
    Thanks for your response,
    I have updated the description.
    I wish to fully charge my 220Ah battery from 20% to 100% in 2hours
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  • lightsky
    lightsky Registered Users Posts: 13 ✭✭
    #5
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    Photowhit said:
    Vic said:

    Having a carefully-considered system design,  is essential,     BEFORE     buying any system components.
    This!!! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Way too many variables t just say one thing. 

    If you are setting up a small system a more expensive 12 volt nominal that would work with a cheap PWM charge controller might be best.

    Trying for a mobile array on a tiny home or RV? or some pole mounted systems or even a small roof. Then the panels efficiency might be primary (How well the panel converts available sunlight to wattage) 

    Setting up a free standing array in a field, best price per watt, excluding poor life time panels or toxic materials.
    Appreciated.
    I would prefer MPPT charge controller.
    I'm considering 2x 400w PV connected in parallel but maybe I'm getting it wrong. 
    I have updated the description to accommodate more information.
    Thanks
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #6
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    lightsky said:
    I wish to fully charge my 220Ah battery from 20% to 100% in 2hours.
    It looks like this is a flooded lead acid battery. I haven't heard of bulk rates above 20-25% and once the battery reaches about 80% full the battery metallurgy/chemistry will restrict the charging to less. I suggest finding a charging manual for your battery.

    You may have to change battery types to reach the charging rate for the amount of capacity you would like. Lithium can take a higher rate of charge...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
    · Share on Twitter

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