Mega Watt Hour

Unit of measurement for the amount of energy produced or consumed in one hour.

What is a Megawatt-hour ?

The Megawatt-hour is a unit of measurement of energy. Its abbreviated form is MWh.

Be careful not to confuse Megawatt and Megawatt-hour: if the two units are related, they do not designate the same thing.

Indeed, a Megawatt indicates an energy power at a time t. The Megawatt-hour unit is used to evaluate a quantity of energy produced or consumed during a given period of time. As its name indicates, the reference time taken into account to quantify the energy in MWh is one hour.

1 MWh is therefore equivalent to the amount of energy produced or used during one hour, at a power of one Megawatt (MW). This corresponds to 3.6 Gigajoules (GJ) in the official measurement system used by the international scientific community.


The specificities of the Megawatt-hour

The Megawatt-hour (MWh) is a derivative of the Watt-hour (Wh) in the same way as the Kilowatt-hour (kWh), the Gigawatt-hour (GWh) and the Terawatt-hour (TWh).

For comparison, 1 MWh corresponds to 1000 kWh and one million Wh (or 106). In the opposite direction, it takes 1000 MWh to make 1 GWh, and a million MWh to make 1 TWh.

To convert Kilowatt-hours to Megawatt-hours, the number must be divided by 1000. The operation can be useful to compare energy consumption at significant levels.


Examples and practical application

Like the Wh or the GWh, the MWh is used to measure a quantity of energy, whatever its nature. It can be used to evaluate gas or electricity consumption, but rather on the scale of a large company.

Indeed, 1 MWh corresponds to a relatively large amount of energy. At the individual level, the preferred unit for gas or electricity consumption is the kWh, which is the most relevant.

The unit MWh can also be used to evaluate a quantity of energy produced: at the level of a power plant, for example. However, it is not really suitable for measuring the amount of energy stored in vehicle batteries, which is limited to about 100 kWh.

With the proliferation of electric vehicles consuming between 15 and 20 kWh of electricity every 100 km, the management of a vehicle fleet requires the MWh as a unit of comparison for the calculation of consumption and operating costs1.


Megawatt-hour in figures

In France, the capacity of the grid-connected solar photovoltaic park in 2019 was 9.4 GW, or 9400 MW. In the same year, the production of electricity from photovoltaics was 11.6 TWh or 11.6 million MWh2.

If electricity production at the level of a country like France is now expressed in terawatt-hours, the Gigawatt-hour is more appropriate to compare the amount of energy produced by sector (nuclear, hydro, solar, wind...). At a lower level, the Megawatt-hour is used more to estimate the electricity produced at the level of a particular power plant or even a domestic solar installation.

For example, the thermal power plant in Le Moule has an installed capacity of 102 MW, which allowed it to produce 549, 000 MWh of electricity in 20173.

In the southern regions of France, the amount of energy produced can range from 1.1 to 1.4 MWh/kilowatt peak (kWp). Knowing that a classic solar installation has a typical power of 3 kWp, the average electrical production can reach about 3 MWh over a year.


Regulatory framework

Not applicable