NABCEP Solar Site and Shading Analysis 4

Question 1

When measuring roof azimuth with a compass for solar site assessment, which correction must be applied to obtain the true azimuth?

Accepted Answer

Apply magnetic declination correction for the geographic location

Answer

Compass measurements read magnetic azimuth; applying the local magnetic declination (adding for westerly, subtracting for easterly) converts the reading to true geographic azimuth needed for accurate solar modeling.

Question 2

An array installed at 35°N latitude uses a fixed tilt equal to the site latitude (35°). To maximize annual energy production, what would be the optimal adjustment to this tilt for a summer-peak load application?

Accepted Answer

Decrease tilt to approximately 20–25° to better capture high summer sun angles

Answer

A tilt lower than site latitude (roughly latitude minus 10–15°) optimizes for summer when the sun is high; latitude tilt optimizes for annual average, not specifically summer production.

Question 3

A homeowner's neighbor plants a row of fast-growing Leyland cypress trees. What site assessment tool or documentation should a solar professional recommend creating NOW, before the trees grow?

Accepted Answer

A baseline shading analysis report documenting current solar access percentages by month

Answer

Documenting current shading conditions creates a legal and technical baseline to demonstrate future shading impact if the trees grow and reduce energy production, supporting any dispute or easement claims.

Question 4

In NREL's PVWatts calculator, the 'Array Type' input that accounts for single-axis tracking of the modules affects which output parameter most directly?

Accepted Answer

Annual AC energy production (kWh)

Answer

Selecting single-axis tracking in PVWatts increases the modeled annual AC energy production because the array follows the sun's east-west daily motion, capturing more irradiance throughout the day.

Question 5

A ground-mount array is designed with row spacing to prevent self-shading at a specific 'design sun altitude.' Which sun altitude angle is the NABCEP standard practice for limiting inter-row shading in the continental US?

Accepted Answer

Solar altitude at 10 AM on the winter solstice (approximately the lowest critical sun angle)

Answer

NABCEP best practice uses the winter solstice at 10 AM (and 2 PM) as the design sun angle for row spacing to prevent self-shading during the period of lowest sun angles in the year.

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

NABCEP Solar Site and Shading Analysis 4