Need to power 24 volt 100 watt gate opener and 120 watts of 12 volt led light bulbs.

LJ1
LJ1 Registered Users Posts: 10 ✭✭
I have 4 12 volt 20 watt panels which will provide me 24 volts at 40 watts, I was going to go thru charge controller to 2 group size 75 automotive batteries, was going to hook up 2 light in series so could use 12 volt bulbs. Is this a feasible setup to power gate opener and lights at night?

Comments

  • mvas
    mvas Registered Users Posts: 395 ✭✭✭
    edited December 2019 #2
    No ... use "deep-cycle" batteries, do not use automotive style batteries.
    Are you sure it is OK to wire the two bulbs in SERIES?
    Will the lights be on all night?
    How many hours and how many watts?
    Battery DOD?
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Was going to use Costco Interstate batteries because they will kinda, give me new ones within 3 years,
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Not sure about hooking lights in series but assumed I could do that.
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Have 8 pole lights with 3 bulbs in each, bulbs are 12 volts at 5 watts each. was thinking could hook every 2 poles in seriies to reduce them to 12 volts each?
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Would like to power all night, but if not just few hours or use less lights. Depth of discharge have no idea.
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,036 ✭✭✭✭✭
    "I have 4 12 volt 20 watt panels which will provide me 24 volts at 40 watts"

    80 watts is 80 watts at whatever voltage you chose. The difference will be the amount of current the panels will produce.
     A 2s2p wiring configuration will give you twice the Vmp and twice the Imp as a single panel. Which will, on paper, = 80 watts.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    You can put filament bulbs in series without problem (other than if one burns out, you use all series bulbs until repaired)--Think old style Christmas lights.

    Fluorescent, LED, and such lamps... I would avoid placing them in series. You could try--But I fear that their ballasts may be unstable in series and could burn out in some cases from over voltage.

    For LED lamps, look around, there are some that have a pretty wide input voltage range (the design of their ballast). Here is a 12-24 volt LED lamp (just an example, I have never tried them):

    https://www.amazon.com/Voltage-12V-24V-Traditional-Equivalent-400Lumen/dp/B071K8KKHY

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Thanks guys, already ordered 12 volt bulbs. I am cheap so ordered 18 of them for about $40. May run lights off transformer. and only run gate and a 12 volt camera or two off solar.
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Just ordered transformer for under $30, probably better oprption for lights.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    What is your "transformer"? A boost mode DC to DC converter (switching power supply), or just a standard AC to AC transformer?

    Also, really should do a design based on your loads... It is surprising how fast loads that are on 10-14 hours per "overnight" add up... And losses from solar power in to AC or DC power out (typically somewhere around 50-60% efficiency).

    I suggest motion detector lights for security--Rather than a few lone lights highlighting stuff to steal and providing dark areas to skulk around. As well as saving lots of energy.

    For example, 8 fixtures * 3 bulbs * 5 Watts each * 14 hours per night = 1,680 Watt*hours per night

    Assume winter with 3 hours of sun per day (depends on where you live, but 3 hours per day in winter is quite a bit of sun):

    1,680 WH per night * 1/0.61 DC solar end to end eff * 1/3.0 hours of sun = 918 Watt solar array "break even"

    Battery size:

    1,680  WH * 1/12 volts * 2 days of storage * 1/0.50 max discharge = 560 Amp*Hours @ 12 volt battery bank minimum

    The above are minimum estimates, and will change based on where you live (hours of sun), and other stuff... But this is not a "trivial" solar installation--It is fairly large for security lighting alone.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    Sorry for newbie questions. Can you wire solar panels with low voltage weatherproof wire? Or do you have to use the specific wiring with strange connectors?
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I must have missed something because I don't understand why there's series lights and a transformer in the discussion.

    4 x 12v nominal panels wired in parallel to pwm charge controller, charging 2x 12v batteries, also in parallel, powering 12v bulbs?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    You can buy mc4 connectors+crimp tool, buy mc4 pig tails or simply cut off connectors and use water proof connections--but this generally voids your warranty.
    The wire, if exposed to sun and water, you should use UV rated outdoor wiring for exposed runs.
    Non UV rated insulation will crack and fail over time with soon exposure.
    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    I was going to try to power lights with solar, but seems smarter to just power gate opener with solar and power lights with transformer.
    Have one 24 volt 20 watt panel that I am guessing can charge 2 small 12 volt batteries in gate opener.
    At $11 a panel they seem like too big a bargain to return, probably use the four 12 volt 20 amp panels on shed for lighting in backyard. 
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,036 ✭✭✭✭✭
    What are the actual specs for the panel? A 24 volt "nominal" panel typically has about 36 volts under load and 44 - 46 volts, open circuit.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • LJ1
    LJ1 Registered Users Posts: 10 ✭✭
    1. Aleko sp20w24v 20 watt got from Amazon for $26 used like new

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Aleko looks to be a 36 cell panel, which would be Vmp~18.0 volts (+/- 0.5 volts)--Guessing. Further down in specs, says Operating Voltage is 17.5 volts (should be Vmp--Voltage maximum power).

    That, nominally, would be a panel for charging 12 volt batteries with a PWM type charge controller.

    The specs are a little bit confused:
    • 20 watt monocrystalline solar panel with a nominal output voltage of 24 volts
    • A solar panel will lower the costs on your power bill and help curb your carbon emissions
    • Operating Voltage: 17.5 volts
    • Rated maximum power: 20 watts; Voltage at Pmp: 35.2 amps; Current at Pmp: 0.57 amps
    Nominal amps would be (if trusting any of above data):
    • 20 Watts / 17.5 Volts Vmp = 1.14 Amps Imp
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset