Hello SAM,
From what I read, capacity factor calculations always use the
actual AC kWh electricity generated in one year in their
numerator. This AC electricity must contain the effect of the overall derate factor. The
denominator, however, could be expressed in
DC (after PV panels) or AC power (after inverter) multiplied by 8760 hours.
Question: Does this mean that AC power should include the contribution of inverter efficiency only and not the entire derate factor?
Therefore, is the following, correct?
- Solar panel rated DC power = 100 kW-dc
- inverter efficiency = 95%
- Inverter output AC power = 95 kW-ac
- derate factor = 80%
- Power after overall derating = 80 kW-ac
- AC kWh generated in one year = 175,200 kWh-ac
DC CF = 175,200 kWh-ac / (100 kW-dc x 8760 h) = 0.2 or 20%
AC CF = 175,200 kWh-ac / (95 kW-ac x 8760 h) = 0.21 or 21%
And would this be incorrect:
AC CF = 175,200 kWh-ac / (80 kWh-ac x 8760 h) = 0.25 or 25%
Many thanks!
Best,
Arman