NABCEP Small Wind Installer

Question 1

What is the generally recommended minimum average annual wind speed for a cost-effective small wind turbine installation?

Accepted Answer

10 mph (4.5 m/s)

Answer

A minimum average annual wind speed of approximately 10 mph (4.5 m/s) is generally required for a small wind system to be economically viable.

Question 2

Wind power is proportional to the cube of wind speed. If wind speed doubles, how does the available power in the wind change?

Accepted Answer

It increases by a factor of eight

Answer

Because wind power follows P ∝ V³, doubling the wind speed increases available power by 2³ = 8 times.

Question 3

Which instrument is the primary tool used to measure wind speed during a small wind site assessment?

Accepted Answer

Anemometer

Answer

An anemometer measures wind speed and is the standard instrument used in wind resource assessments to collect site data.

Question 4

Per the widely accepted '30-foot rule,' how much taller should a small wind turbine hub be above any obstruction within 500 feet of the installation?

Accepted Answer

30 feet

Answer

The 30-foot rule states a turbine hub should be at least 30 feet above any obstruction within 500 feet to avoid turbulent wake effects that reduce output and increase fatigue loads.

Question 5

What is the Rayleigh distribution used for in small wind site assessment?

Accepted Answer

Modeling the statistical frequency of wind speeds at a site

Answer

The Rayleigh distribution is a statistical model that estimates how often each wind speed occurs at a site, enabling annual energy production estimates.

NABCEP - North American Board of Certified Energy Practitioners Practice Test

NABCEP - North American Board of Certified Energy Practitioners Practice Test

NABCEP Small Wind Installer