Why the increase in the electric bill, and what's a Kill-a-Watt

I've been running my unRaid server (see prior posts) 24 hours a day for a little more that one month now. Just received my electric bill and it was about $30 more than last month. Yes, we've been running the air conditioners but it seems to be more when compared to last year, but I needed to understand what was going on. But how??

Well with a Kill-a-Watt meter and here's what one looks like.

Okay, but what does it do?
The meter once connected to your appliance will assess how efficient they really are. The display will count consumption by the kilowatt/hour, same as your local utility. You can track minute-by-minute changes in electric consumption as major appliances are turned on and off. It lets you track the amount of electricity that your household uses in real time. It helps you reduce your energy consumption and decrease your monthly bills. The unit displays the total cumulative appliance power consumption in kilowatt hours (KWH). The unit will display KWH from 0.01 KWH to 9999 KWH.


So, I plugged this into the wall, and then plugged my server into the meter. I then powered on the server. The meter showed that my server uses 175W. I then spun down the 5 internal hard drives, and the meter showed that it now used only 143W.

Knowing this information,..I could "guesstimate" how much it costs each month to run the server.
In the US, 1 Watt running 24x365 costs about $1/year. Multiply the Watts being pulled by the server, times 8.76 to give you kWh for an entire year.

In the US, 1 kWh costs about $0.12, so a server that pulls 40 Watts, costs $42/year to run 24x365.... less in many places. According to the math where 1 Watt is about $1 per year,....175/12 = $14.58 per month. Of course that assuming constant 175W. With drives spun down 143/12 = 11.92 per month

So, this helps explain why I saw a bump in my electric bill.

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