MW, MWh and MVA converter
MW measures power, the rate of flow; MWh measures energy, power over time: MWh = MW × hours. MVA is apparent power, and MW = MVA × power factor.
h
8,760 h in a year, 24 h in a day
Energy
876,000MWh
100 MW for 8,760 h
Method and data
Formula
E (MWh) = P (MW) × t (h) P (MW) = S (MVA) × pf Q (Mvar) = S × sin(acos pf) S = sqrt(P^2 + Q^2) I (A) = S (VA) / (sqrt(3) × V_LL)
Worked example
| Power × time | Energy |
|---|---|
| 100 MW × 1 h | 100 MWh |
| 100 MW × 24 h | 2,400 MWh |
| 100 MW × 8,760 h | 876,000 MWh |
| Power factor | P (MW) | Q (Mvar) | Angle phi |
|---|---|---|---|
| 0.8 | 80 | 60 | 36.9° |
| 0.9 | 90 | 43.59 | 25.8° |
| 0.95 | 95 | 31.22 | 18.2° |
Assumptions
- A year has 8,760 hours, or 8,784 in a leap year.
- Power is constant over the period. For a varying output, the same formula holds with the average power.
- The power triangle assumes sinusoidal voltage and current at one frequency; harmonics are ignored.
- Q is shown as a positive magnitude. A lagging (inductive) load and a leading (capacitive) load with the same power factor have the same magnitude of Q.
- Three-phase current assumes a balanced load and uses the line-to-line voltage; single-phase current uses the voltage across the load.
Definition: Power Factor
Guide: Electricity market units explained
On the Tera Intelligence map, each power plant, substation and line opens with its rated capacity and technical specifications, so a converted figure can be checked against the asset it describes. Explore the map
Questions
- What is the difference between MW and MWh?
- MW is a rate and MWh is an amount: a megawatt measures power at an instant, and a megawatt-hour is the energy delivered when one megawatt flows for one hour. A 100 MW plant at full output for one hour produces 100 MWh, and over a full year of 8,760 hours it would produce 876,000 MWh. Real plants produce less than that maximum, which is what the capacity factor measures.
- How do I convert MVA to MW?
- Multiply by the power factor: MW = MVA × pf. A 100 MVA load at a power factor of 0.9 draws 90 MW of active power, and the rest of the apparent power is reactive: Q = 100 × sin(acos 0.9) = 43.6 Mvar. Without a power factor the conversion cannot be made, because MVA includes reactive power that does no useful work.
- What power factor should I assume?
- Use the figure from the equipment data sheet, the connection agreement or the grid code, not a rule of thumb. Many grid codes ask generators to be able to operate anywhere between 0.95 leading and 0.95 lagging; in the United States, FERC Order 827 (June 2016) set that range for new wind and solar plants. Synchronous generator nameplates commonly state a rated power factor of 0.8 to 0.9. The 0.9 used on this page is a default for the worked result, not a recommendation.
- How many homes does 1 MW power?
- It depends on how much electricity a household uses and on the plant's capacity factor, so no single figure is right. Homes = (P × 8,760 h × CF) / annual consumption per household. Hypothetical example, not an average: a 1 MW plant with a capacity factor of 25% produces 1 × 8,760 × 0.25 = 2,190 MWh a year; if each home used 5 MWh a year, that would equal the yearly use of 438 homes. Household consumption differs several-fold between countries, so use the local figure, and note that matching yearly energy is not the same as supplying those homes at every hour.
- How do I convert MVA to amps?
- For a three-phase circuit, divide the apparent power by the square root of 3 times the line-to-line voltage: I = S / (sqrt(3) × V_LL), with S in VA and V in volts. 100 MVA at 132 kV gives 100,000,000 / (1.732 × 132,000) = 437 A. For a single-phase circuit, I = S / V. Current follows MVA, not MW, so a lower power factor means more current for the same active power.
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