Evaluating small wind turbine performance

How much electricity will a small wind turbine deliver at a proposed site? Start with the wind-speed distribution at hub height and the turbine power curve. A rated output tells you the power under defined conditions. For energy, multiply the curve’s output in each wind-speed bin by the hours expected in that bin and add the results.

Move from gross to useful energy

Document the source of the curve, air density, availability, electrical losses and shutdown assumptions. At a hybrid site, distinguish turbine output from energy delivered to the loads or storage. Surplus may be curtailed when the battery is full. To compare models, hold the wind distribution, metering boundary and system assumptions constant. A scenario with different mean wind or a different loss allowance answers a different question.

Stress-test the economics

Compare conservative, central and favourable cases for wind resource, service downtime and installed cost. Value delivered energy at the marginal cost it actually displaces. Distinguish avoided grid electricity from delivered diesel and include replacements and maintenance over the comparison period. Ask for raw pilot data and an agreed metering boundary before using a modelled estimate in a purchase decision.

Continue with Small wind for telecom and Hybrid microgrids. Source: U.S. Department of Energy, Small Wind Guidebook.