Capacity factor — Hyunjoo Park

The capacity factor is the average power divided by the nominal (rated) power: $C_f = \frac{P_{avg}}{P_{nom}} \qquad E_{year} = C_f\, P_{nom}\, t_{year}, \quad t_{year} = 8760\ \text{h}$

Why < 1: the source is not always there (night, winter, low wind) and the plant is not always running at full power.

Same energy, lower $C_f$ → more installed power: $P_{nom} \propto 1/C_f$ .

Area: with nominal power density $P_{nom}/A$ [W/m²]: $A = \frac{E_{year}}{C_f\, (P_{nom}/A)\, t_{year}}$

Typical trap

Without $t$ the units don’t work: W/m² × m² = W (power), × h → Wh (energy).