Battery based security lighting help

BB.
BB. Super Moderators, Administrators Posts: 33,613 admin
This discussion was created from comments split from: how to design a solar street light?.
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset

Comments

  • uisraan
    uisraan Registered Users Posts: 1
    Hi
     my question is :
     If I have a: 100 watts LED
     runs 8 hours per nights
    3 days back up
     12 volts battery
     discharge limit of battery is 75%
     4 hours sun a day
     temperature( min -7' c) and (max +37' c)
     can you please help me to calculate , what size battery and panel do I need ?
     thank you so much
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    edited August 2016 #3
    Uisraan, welcome to the forum.

    I have split your questions into a separate thread to keep things focused on your needs.

    Questions:
    • Are these 12 volt LED lights or 120 VAC (will you be using an AC inverter)?
    • 100 Watts of LEDs is a lot--Can you use less power and/or use motion detector based lights to save energy?
    • Do you have any 120 VAC utility power available nearby--If you are going to use a lot electricity, utility power is generally cheaper and more reliable
    • Is this a short term installation and/or seasonal usage (i.e., summer camp)?
    • What is your worst case need... I.e., Winter, stormy weather, 12+ hours of lighting and 5 days of cloudy weather?
    • Will there be somebody to monitor the system (recharge battery bank during bad weather/etc.).
    -Bill

    PS: I should add, roughly where will the system be installed (hours of sun per day)?
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    A lot of the LED's sold around here are labeled "100 watt equivalent", but the bulb may draw only 12 or 14 watts.  I wonder what the OP really has for a load...

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i