Today we are going to talk about Kilowatts VS Kilowatts hours and Power VS Energy. Solar is a classic jargon overload and these two and some of the most common stumbling blocks.
But not anymore!
Now, if you are getting confused, don’t beat yourself up. Even we say the wrong thing sometimes for which we are constantly reminded. We love the accountability though so keep the comments coming and for the record, we know the difference but we are guilty of being lazy and saying kilowatt when when should add an “hour” at the end.
You will come across both a lot, especially when you are looking at a battery for your home or business.
Fortunately, the difference is easy!
A kilowatt is a measure of power and a kilowatt hour is a measure of energy.
I am guessing you now have more questions than answers which would be fair. So, to break it down properly starting with a kilowatt.
Now, if we look at the actual word.
Kilo as a prefix is derived from a greek word χίλιοι (chilioi), which has been adapted into kilo, as we like to say, meaning 1000 and thus a kilowatt is the measure of 1000 watts. You will commonly see kilowatts represented with the abbreviation of a small k next to a big W.
Then looking at a kilowatt hour. A kilowatt hour is how many kilowatts is required to run something for an hour. You will often see it abbreviated as a small k next to a big W followed by a small h.
So to put it simply, power is the rate at which energy is generated or used. Energy is the measurement of how much power is required over a period of time.
A simple analogy is a small compact globe like this, it needs 20 watts of power to work so it would thus require 480 watt hours of energy to run for a day or 3.36kWh to run for a week.
The maths is 20 watts times 24 hours equals four hundred and eighty watts which can then be multiplied by seven to get it’s weekly energy requirement which is three thousand three hundred and sixty watts or 3.36kWh more simply.
When you are reading about something like a solar battery, the amount of power it can push out at any one time for your home to use will be represented in kilowatts (kW) and how long it can do it for will be represented in kilowatt hours (kWh).
For example, if we look at something like a Tesla Powerwall 2. It has 13.5 kilowatt hours of usable capacity and can discharge at a maximum of 5 kilowatts an hour. That means it can push out up to 5 kilowatts at any one moment which is pretty huge and it can maintain that load for over 2 and a half hours.
Hopefully that has cleared everything up so you now know the differences between kilowatts and kilowatt hours and power vs energy.