# Define kw and kwh relationship

### What is a kWh? kW and kWh explained | OVO Energy

The important difference between kWh and kW is that a kWh reflects the total amount of electricity used, whereas a kW reflects the rate of. The kilowatt hour is a unit of energy equal to megajoules. If energy is transmitted or used at a constant rate (power) over a period of. What is the Difference Between a Kilowatt and a Kilowatt-hour (kW vs. kWh)?. What the heck is How is That Measured in Relation to Solar? For the purpose of.

If you do you may end up with a solar system that is completely the wrong size! How do kW and kWh relate to batteries? When buying batteries, you need to think about both the power of the battery and the energy storage capacity of the battery you are looking at. The energy storage capacity of the battery is measured in kWh. Its power is 5 kW, so it can charge or discharge at that rate.

At full power, then, it can fully discharge in under 3 hours. The more energy kWh a battery has the more you can store and the longer it will last, the more power it has the faster you can get that energy in our out of the battery, In other words the more power it has, the more appliances you can power with it and the more energy it has, the longer you can power those appliances.

For normal household use, you want enough energy to get you through the night and at least 5 kW of power for speedy charging.

Top tip for filtering out the worst solar and battery salesmen: Ask them to explain the difference between a kW and kWh. If they get this wrong how on earth are they gonna understand your requirements? A lot of cold calling door knockers will fail this test in my experience. The technical bit for those that are interested: Energy is measured in Joules.

Energy is the capacity of something to do work. Power is measured in Watts. If you find yourself using this unit, double check what you really mean. Which is probably kilowatt-hour.

### What's the Difference Between kWh and kW? - Artis Energy

Kilowatt is a measure of power units: Joules per second so you are really saying joules per second per second, or joules per second squared. Which would be a measure of how quickly power is increasing.

An acceleration of power if you like. There are very few circumstances where that is a relevant measure. Especially when talking about solar or batteries.

That's with " Calories" meaning kilocalories, which is the unit that is almost always meant when people talk about the "calories" in food. Energy can change form. We could eat the biscuit to provide us with energy. Or we could burn the biscuit and turn it into heat energy. Given the right equipment we could turn the heat energy from the burning biscuit into electrical energy to run lights and fans and so on.

Some energy would be wasted in the conversion process, but it should be possible to get that burning biscuit to run a light bulb for at least a few seconds. Probably the best option would be to eat the biscuit, but hopefully you get the general idea - the biscuit contains energy that can be converted into different forms Electricity and other fuels supply energy in a form that we can use to run the equipment in our buildings. Our biscuits contain a certain amount of energy - Calories or 0.

But biscuit energy is not in a form that we can easily use to run the equipment in our buildings However, we can easily make use of electricity. And, provided we've got a gas or oil burner, we can easily make use of gas or oil. One form of energy comes through wires isn't electricity clever?!

At the end of the day it's all just usable energy in different forms. We can express quantities of these forms of energy in terms of kWh.

We buy or generate the kWh of energy, and we use it to fuel the equipment in our buildings. The relationship between energy consumption kWh and time A typical building uses more energy over long periods of time than it does over short periods of time: On February 16th a building might have used 95 kWh.

What is a Kilowatt hour?

Over the week starting April 12th it might have used kWh. From January 1st to December 31st it might have used 31, kWh. Given the three figures above, we can easily see that the building used more energy over the course of than it did on February 16th However, we can't immediately compare the efficiency of the building over each of those periods. If a kWh figure covers a day, we can only compare it fairly with other kWh figures that cover a day.

If a kWh figure covers a week, we can only fairly compare it with other kWh figures that cover a week. If we have the kWh from February and the kWh from March, we can't really compare the two figures fairly, because February is typically 28 days long, whilst March is 31 days long. This article explains more about the problems that arise if you compare the kWh used in one month with the kWh used in the next.

Energy consumption expressed in terms of kWh doesn't often mean much unless you also know the length of the period that the kWh were measured over. And it's difficult to make fair comparisons between kWh figures unless they are all from periods of exactly the same length.

Figures expressed in terms of power e.

Power is the rate at which energy is generated or used. The kW is a unit of power. Strictly speaking energy isn't actually generated or used, it's converted from one form into another. Like how the energy stored in oil is converted into heat when you burn it.

## Kilowatt hour

And like how the electricity that runs a fan is converted into the motion of the fan blade kinetic energy. But this is a distinction that people generally don't worry about when they're staring at an excessive energy bill and wondering how they can "use" less energy.

So power is a measure of how fast something is generating or using energy. The higher a building's kW, the faster that building is using energy. Joules per second makes it obvious that power is the rate at which energy is being generated or used. It's like how miles per hour makes it obvious that speed is the rate at which distance is being travelled. James Watt The watt W is another unit of power. It doesn't make it quite so obvious what power means.

But the watt is actually just another name for Joules per second. Just some bright spark decided that equations and whatnot would be simpler if power had its own unit instead of being expressed using units of energy and time together. And they named this unit after James Watt, the Scottish inventor who had an important hand in the development of the steam engine.

The watt W is a measure of power And the kilowatt kW is a measure of power too one kW being watts. Things that "generate power" Items of equipment like boilers, electricity generators, and wind turbines, take energy in one form e. There's a limit to how much useful stuff these things can generate, and that is expressed as the rate at which they can generate energy.

Which is, by definition, their power. Consider a 10 kW wind turbine Provided it has the optimum level of wind which probably doesn't happen nearly as often as its owner would likeit can generate 10 kW of power. How long does it take to generate 10 kW? That's a question that would only be asked by somebody that didn't understand what power was.

It's a bit like asking "how long does it take to travel 10 miles per hour? The two are closely connected, but we'll get to that shortly. Things that "use power" Items of electrical equipment like light bulbs, computers, and fans, take energy in the form of electricity, and use it to do useful things for us.

Really they're converting the energy into other forms heat, motion etc. The rate at which these things use energy is their power. Or, depending on the thing, and the person you're talking to, you might hear it called their "load" or their "demand", or you might just hear it referred to in terms of a W or kW value.

Light bulbs are a simple example: The watts aren't affected by how long the W light bulb is running for A second, an hour, a day - no difference - so long as it's switched on it will be using W of power. If it's not switched on it won't be using any power i. Some equipment is more complicated. It depends on what it's doing - if it's sitting there doing nothing it'll probably use less power than if you're hammering away on an Excel spreadsheet, listening to some music, and burning a DVD, all at the same time.

We make a distinction between instantaneous power and average power: Instantaneous power The instantaneous power or instantaneous demand, or instantaneous load is the power that something is using or generating at any one moment in time.

Put your laptop on standby and its instantaneous power will drop immediately. Bring it back to life and its instantaneous power will rise immediately. If, at any particular moment, everything in an office building is switched on, that office building might be using 42 kW of power.

That's 42 kW of instantaneous power. If, at any particular moment, everything in the office building is switched off, that building should be using 0 kW of power. That's 0 kW of instantaneous power.

The instantaneous power of most buildings varies constantly. People are constantly switching things on and off, and many items of equipment within the building have instantaneous power that is constantly changing too.