Solar Powered Christmas Lights Save You Money???
By now you have probably seen the outdoor christmas lights that are solar powered (offer you a savings on your power bill)
Lets find out how long it takes for the lights to pay for themselves.
I have some 3 year old LED lights that i use for decorating the house.
Using a Kill-a-watt meter the 150 light strand uses 4 watts of power.
This is which is 27milliWatts per light.
A new standard 100 LED light strand is $17 from canadiantire.
A solar powered strand of 50 LED lights is $25 from canadiantire, so 100 lights would cost ($25 * 2)=$50. These solar powered lights will stay on for up to 6 hours per day.
The cost difference is ($50-$17)=$33. So we need to save $33 off our power bill to break even.
Now lets calculate how many hours we need to operate the regular strand to reach the break even point.
I pay $0.07 per kwh from the power company.
27mW * 100 = 2700mW = 0.0027kW = killowatts used per strand.
$33 = ($0.07/kwh)*(0.0027kw * hours)
($33/$0.07kwh) = (0.0027kw * hours)
471kwh = (0.0027kw * hours)
471kwh/0.0027kw = hours
174603h = hours
So to be cost effective we need to use the solar lights for more than 174,603 hours which is 7275 days (or 20 years) of constant use. But lets not forget that the solar powered lights only operate for 6 hours per day.
174603h/6hours per day = 29,100 days at 6 hours per day
29100/365 = 80 years at 6 hours per day, (everyday of the year).
Now if you used your christmas lights for 3 months a year (any more than that is just silly) you get:
80/0.25 = 320 years (at 3 months a year (for 6 hours a day)).
To summarize, you would need to use a strand of lights for 320 christmas seasons for it to become cost effective to buy a solar powered strand of lights.
But wait, there’s more.
A typical LED has a life of 50,000 hours, but by the math above we would require 174,603 hours to reach the break even point. So it is not even remotely likely that the LEDs would last the time required to get to the 320 seasons to break even (… i am not even going to get into the life of the solar panel).
So save your money… dont buy solar powered christmas lights.
Posted by mb under Tips | Comments (3)
