Battery based security lighting help

BB.

This discussion was created from comments split from: how to design a solar street light?.

uisraan

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.

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)?

vtmaps

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