FREE NABCEP PV Design Specialist Questions and Answers

Question 1

What is the primary consideration when selecting the orientation of PV modules in the Northern Hemisphere?

Accepted Answer

South

Answer

The latitude of the installation site is the most crucial factor for determining the optimal tilt angle for fixed PV modules. Setting the tilt angle approximately equal to the latitude allows the modules to receive the most direct sunlight annually. This maximizes the amount of solar energy captured over the year, leading to optimal system performance.

Question 2

Which factor is most important when determining the tilt angle for PV modules in a fixed-tilt system?

Accepted Answer

Latitude of the installation site

Answer

A shading analysis is an essential step during the design phase of a PV system to identify any potential obstructions, such as trees, chimneys, or adjacent buildings, that might cast shadows on the PV array. Even partial shading can significantly reduce the output of an entire string of modules. By identifying and mitigating shading, designers can optimize module placement and predict accurate energy production.

Question 3

What is the purpose of a shading analysis during the design phase of a PV system?

Accepted Answer

To identify potential obstructions that could reduce system performance

Answer

The azimuth angle, which is the compass direction the PV modules face, is critical because it directly influences the amount of solar radiation the modules will receive throughout the day. Optimizing this angle, typically towards true south in the Northern Hemisphere, maximizes the system's exposure to sunlight. This ensures the highest possible energy production from the PV array.

Question 4

When designing a PV system, why is it important to consider the azimuth angle?

Accepted Answer

It influences the amount of solar radiation the modules will receive

Answer

Higher operating temperatures significantly decrease the efficiency of PV modules. As the temperature of the solar cells rises, their voltage output drops, leading to a reduction in overall power production. This phenomenon highlights the importance of proper ventilation and cooling considerations in PV system design to maintain optimal performance and energy yield.

Question 5

How does temperature affect the performance of PV modules?

Accepted Answer

Higher temperatures decrease module efficiency

Answer

The 'derate factor' in PV system design is a crucial multiplier that accounts for various losses that reduce the actual energy output compared to the theoretical maximum. These losses include factors like temperature effects, wiring resistance, inverter efficiency, module degradation, and soiling. Applying a derate factor provides a more realistic and accurate estimate of the system's expected performance over time.

NABCEP - North American Board of Certified Energy Practitioners Practice Test

NABCEP - North American Board of Certified Energy Practitioners Practice Test

FREE NABCEP PV Design Specialist Questions and Answers