Calculator Inputs
Example Data Table
| Parameter | Example Value | Unit | Why It Matters |
|---|---|---|---|
| Average wind speed | 6.8 | m/s | Higher wind speed sharply increases energy yield. |
| Hub height | 100 | m | Taller hubs often reach faster and steadier winds. |
| Rotor diameter | 120 | m | Larger rotors sweep more area and capture more energy. |
| Rated power | 3200 | kW | Rated output limits maximum turbine production. |
| Total non-efficiency losses | 15 | % | Wake, icing, curtailment, and other losses lower net yield. |
Formula Used
1) Hub height wind speed
Vhub = Vref × (Hhub / Href)α
This power-law adjustment estimates wind speed at the turbine hub from the measured speed at a known reference height.
2) Swept area
A = π × (D / 2)2
Rotor diameter determines how much moving air the turbine can intercept.
3) Weibull-adjusted equivalent speed
c = V̄ / Γ(1 + 1/k)
E[V³] = c³ × Γ(1 + 3/k)
Veq = (E[V³])1/3
This adds distribution realism by using the Weibull shape factor instead of relying only on the mean speed.
4) Aerodynamic power
P = 0.5 × ρ × A × Cp × Veq3
The calculator converts this to kilowatts and caps it at the turbine rated power.
5) Net annual energy
Net Energy = Gross Energy × ηmech × ηelec × Availability × (1 − losses)
Losses include wake effects, icing or soiling, curtailment, and miscellaneous deductions.
How to Use This Calculator
- Enter the number of turbines and the average measured wind speed at a known reference height.
- Set hub height, rotor diameter, air density, power coefficient, and the turbine power curve limits.
- Add drivetrain efficiency, electrical efficiency, availability, and your expected loss percentages.
- Adjust the Weibull shape factor and monthly multipliers for a more realistic annual production estimate.
- Click the submit button to show the result above the form, review the graph, and inspect monthly yield values.
- Use the CSV and PDF buttons to export the calculated summary and monthly generation table.
Frequently Asked Questions
1) What does this calculator estimate?
It estimates gross and net wind energy output, average power, capacity factor, specific yield, monthly energy, and farm-scale production using turbine, site, and loss assumptions.
2) Why is hub height important?
Wind speed usually increases with elevation. A taller hub can access faster winds, which can raise output significantly because power scales approximately with the cube of speed.
3) What is the Weibull shape factor?
The Weibull shape factor describes how wind speeds are distributed around the mean. Lower values indicate more variability, while higher values represent steadier wind conditions.
4) Why are losses modeled separately?
Separate loss inputs let you reflect real project conditions. Wake effects, downtime, icing, curtailment, and minor electrical or operational issues can materially reduce delivered energy.
5) Does this replace a full bankable energy assessment?
No. This tool is useful for screening and concept design. Bankable studies usually need site measurements, long-term correction, terrain modeling, array optimization, and verified turbine power curves.
6) What do monthly multipliers do?
They scale the modeled monthly hub-height wind speed. Use them to reflect seasonal wind patterns when your site is windier in some months and calmer in others.
7) Why can capacity factor stay modest even with a large rotor?
Large rotors help capture more energy at lower speeds, but capacity factor still depends on wind resource quality, cut-in behavior, rated output limits, downtime, and project losses.
8) What units does the calculator return?
It returns wind speed in meters per second, area in square meters, power in kilowatts, annual energy in kilowatt-hours or megawatt-hours, and carbon offset in tonnes per year.