Wind Farm Layout Spacing Calculator
Calculate the recommended turbine spacing (in rotor diameters) for a wind farm based on rotor size, wind direction spread, terrain complexity, and wake decay. Use this during the layout design phase to balance land use against wake losses.
About this calculator
Optimal turbine spacing is expressed as a multiple of rotor diameter (D) to normalise across turbine sizes. The calculator first computes a base spacing: baseSpacing = rotorDiameter × (5 + (prevailingWindDirectionSpread / 60) × 2). Wider wind direction spreads require greater spacing in multiple directions. A terrain complexity factor then inflates this: terrainAdjustment = baseSpacing × (1 + terrainComplexity), because complex terrain creates additional turbulence and uneven flow. Finally, wake decay is incorporated: wakeAdjustment = terrainAdjustment × (1 + (targetWakeLoss / 100) × wakeDecayConstant), reflecting how quickly wakes recover with distance. The result is divided by rotor diameter and rounded to one decimal place to give the recommended spacing in units of D. Industry norms are typically 5–9 D in the prevailing wind direction and 3–5 D crosswind.
How to use
Example: rotor diameter = 100 m; wind direction spread = 30; terrain complexity = 0.1; wake decay constant = 0.04; target wake loss = 8%. Step 1 — base spacing: 100 × (5 + (30/60) × 2) = 100 × 6 = 600 m. Step 2 — terrain adjustment: 600 × (1 + 0.1) = 660 m. Step 3 — wake adjustment: 660 × (1 + (8/100) × 0.04) = 660 × 1.0032 = 662.1 m. Step 4 — spacing in D: 662.1 / 100 = 6.6 D. So turbines should be spaced approximately 6.6 rotor diameters apart.
Frequently asked questions
What is the recommended turbine spacing in rotor diameters for a wind farm?
The widely used rule of thumb is 5–9 rotor diameters (D) in the prevailing wind direction and 3–5 D in the crosswind direction. Tighter spacing reduces land use and cabling costs but increases wake losses and turbine fatigue. Offshore projects often use 7–10 D spacing because land is not a constraint and larger rotors make wake effects more pronounced. The optimal spacing balances the cost of additional land or cabling against the revenue gained from reduced wake losses.
How does terrain complexity affect wind turbine spacing requirements?
Complex terrain — hills, ridges, forests, and buildings — creates turbulent, non-uniform airflow that makes wakes less predictable and more persistent. In complex terrain, turbines need greater spacing to allow wakes to fully dissipate before reaching downstream machines. A complexity factor above 0.2 typically indicates the need for detailed computational fluid dynamics (CFD) modelling rather than simplified rules-of-thumb. Failure to account for terrain can lead to underperforming turbines and elevated fatigue loads, shortening operational lifespans.
What is the wake decay constant and how does it influence turbine spacing?
The wake decay constant (k) describes how quickly a turbine's wake expands and recovers with downstream distance — higher k means faster recovery. Typical values range from 0.03–0.05 for offshore sites (stable atmosphere, slow wake recovery) to 0.04–0.06 for onshore sites with more atmospheric mixing. A higher k allows turbines to be spaced more closely while achieving the same target wake loss. It is usually determined from site measurements or derived from standard models such as the Jensen (top-hat) wake model used in many planning tools.