Electricity
Cost Calculator

We’ll now implement a kind of electricity
cost calculator
with Matlab...
This calculator will help you estimate
the cost of operating
any
given electrical device or appliance at home, based on the
average kilowatthours
(KWH) used, and on the rate (per kilowatthour) charged by the company
that
supplies you with electricity. 
You need to enter the
estimated power consumed by the device
(in watts), the time of use (in hours) and the electricity rate (in
dollars, or
in your own currency, per KWH).
The
calculation is based on this formula:
where:
ec
= electricity charges
W =
power of device (in watts)
H =
time (in hours)
R =
electricity rate (in dollars per KWH)
The power of the device
is usually mentioned somewhere on
your device. Often, it has a label showing the watts (power) it
consumes when
in use.
Sometimes, the power is not mentioned, but the voltage (in
volts, V) and current (in amperes, A) are mentioned. Power equals
volts multiplied by amperes (W = VA).
We then
create an easy Matlab function to calculate the formula above:
function ec =
electric_cost_calc(w, h, r)
ec = w *
h/1000 * r;
We create another script
to drive the calculator (let's call this driver try_ec.m):
clc;
clear; close all; format bank; format compact
w =
input('Enter
power of your device (in watts): ');
h =
input('Enter
time (in hours): ');
r =
input('Enter
electricity rate (in dollars per KWH): ');
ec =
electric_cost_calc(w, h, r)
To find out how much your
lighting costs are, enter the number
of bulbs you use, then choose a bulb type (in watts). Light bulb
wattage is
usually printed on the bulb. Then you enter the time of use and the
rate
you’re being charged (per KWH, quoted by your electricity company).
Example 1:
You’ve been using 6 60W
ligth bulbs for 3 hours. Your
electricity rate is 13.1 cents per KWH. What’s the charge for this
consumption
of electricity?
We launch our handy
electricitycostcalculator and enter try_ec (or the name
we saved for our driver) on our command window.
Enter power of your
device (in watts): 6 * 60
Enter time (in hours): 3
Enter electricity rate (in dollars per KWH): 0.131
The result is:
ec = 0.14
(that is 14 cents)
Example 2:
You’re experimenting with scientific devices at home. Your
great invention consumes 1200 W during 30 minutes. The assumed
electricity
charges from your company are 16.3 cents per KWH. How much does testing
your
invention cost you?
We launch again our
calculator and get:
Enter power of your
device (in watts): 1200
Enter time (in hours): .5
Enter electricity rate (in dollars per KWH): .163
The result is:
ec = 0.10 (that is 10
cents)
Now, knowing how to
calculate electricity consumption is the first step to energy
savings in the future, right?
From
'Electricity Cost Calculator' to home
From 'Electricity Cost
Calculator' to 'Matlab Examples'
