Calculate wind farm capacity factor, net generation after grid losses, and CfD revenue scenarios.
Model capacity factor, generation, and net load factor
Wind farm capacity factor depends on wind resource quality (location, altitude), turbine efficiency (power curve), and availability (downtime). UK offshore wind: 42–52% CF. Onshore: 25–35% CF.
A 100 MW wind farm running at 42% capacity factor produces 42 MW of power on average over a year (equivalent to 100 MW running at 42% power). UK offshore wind achieves 42–52% CF due to stronger, more consistent winds at sea. Onshore wind achieves 25–35% due to terrain and lower average wind speeds. Hornsea One (world's largest offshore farm, 1,218 MW) has achieved ~40% CF, confirming real-world offshore performance.
Wake Effect and Array Efficiency: Wind farms lose 5–10% of potential output to "wake effect"—turbines downwind of others experience reduced wind speed. Modern optimization (larger spacing, optimized layout) minimizes this. Availability factor (% of time turbines are running) is typically 96–98% for offshore, 94–96% for onshore (requires maintenance, repairs).
Weibull Distribution: Wind speed varies seasonally and daily. UK offshore follows Weibull k≈2, c≈9–10 m/s. Power output is proportional to wind speed cubed (P ∝ v³). Small increases in mean wind speed dramatically increase power output. P50/P90 yield assessments account for historical wind variability.
CfD Mechanics: Contracts for Difference guarantee a strike price. If wholesale market price falls below strike, generator receives difference. If price rises above strike, generator pays difference. AR4 (2019) cleared at £37–40/MWh (2012 real) for offshore. Generator takes full market revenue risk above/below strike. Cost to government: strike price minus forecast reference price, multiplied by generation volume.
Net Load Factor: After grid losses (TNUoS transmission charges, balancing costs), net load factor is typically 97–98%. CfD difference revenue = (Strike Price – Reference Price) × Generation MWh. Reference Price is EPEX-based, published daily. Positive payment when market < strike; negative (generator pays back) when market > strike.