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Topic: Daily power consumption calculation (Read 3855 times)previous topic - next topic

aliakberm92

May 06, 2015, 08:18 pm
Hello,
I am designing a project through arduino that records real time power measurements in WATT and store those values in a local database each 10 seconds. I am confused that how can I calculate daily power consumption by using these values from the database...I get approximately 360 values each hour.

Right now the calculation that I have applied is "taking average of all power values of the day and multiplying them by the number of hours of usage"

P(total) in kWh = P(avg of all values of day) * T (no. of hours of usage) / 1000

Is this calculation perfect? Or rather than taking the avg of all the values do I have to add all the values and then multiply them by the total no. of hours of usage?

Help would be appreciated thank you.

jremington

#1
May 06, 2015, 08:35 pm
A watt is a measure of the instantaneous power usage, while kwh is a measure of the total energy used.

In units, energy=power*time.

If you make a plot of power usage in watts versus hours, the total energy consumed during that time (in watt hours) is the area under that curve. Look up "numerical integration" for several ways to calculate that area.

RPCoyle

#2
May 06, 2015, 08:39 pm
I depends on what you are doing. I do a total Kw calculation on the kilns I run. This means there is a duty cycle... sometime on , sometime off.  I take a reading every second while the kiln is on and add the total watte/seconds to a variable when it toggles off. At the end of the run I convert the variable to Kw hours.

I never checked it against an accurate watte meter, but I think gives me a pretty good ballpark figure for comparing one run to the next.

MarkT

#3
May 07, 2015, 04:19 pm
You just sum the power-time products.

Taking the average and then multiplying is equivalent to summing the power time products,
dividing by the time and then multiplying by the time again.

You don't need a database for this, just a running sum of the energy.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

dlloyd

#4
May 17, 2015, 04:20 amLast Edit: May 17, 2015, 04:20 am by dlloyd
To use the data from the database, just use value*(10/(3600*1000)) to convert each value to energy (kWh). Convert one reading at a time and add to a totalized variable.

mindstormengg

#5
Jul 05, 2019, 09:46 am
To use the data from the database, just use value*(10/(3600*1000)) to convert each value to energy (kWh). Convert one reading at a time and add to a totalized variable.
will the above formula change if i am sending values to the database at a different time period?? If yes, how?
for example i am sending data at every two or three seconds

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