NABCEP PV ASSOCIATE (PVA) EXAM READY - VERIFIED
QUESTIONS AND ANSWERS - COMPREHENSIVE LATEST
VERSION (2026/2027)
1. Q: What is insolation? ANSWER Insolation is the amount of solar
radiation energy received on a given surface area during a given time, typically
measured in kWh/m²/day.
2. Q: What is the solar constant? ANSWER The solar constant is
approximately 1,367 W/m², representing the amount of incoming solar radiation
per unit area at the top of Earth's atmosphere.
3. Q: What is peak sun hours? ANSWER Peak sun hours represent the
equivalent number of hours per day when solar irradiance averages 1,000 W/m².
It's used to estimate solar energy production.
4. Q: What is the difference between irradiance and irradiation? ANSWER
Irradiance is the instantaneous power of solar radiation (W/m²), while
irradiation is the energy over time (Wh/m² or kWh/m²).
5. Q: What is albedo? ANSWER Albedo is the reflective property of a
surface, expressed as a percentage of sunlight reflected. Snow has high albedo
(~80%), while asphalt has low albedo (~5%).
6. Q: What is the optimal tilt angle for a PV array in most U.S. locations?
ANSWER Generally, the optimal tilt angle equals the site's latitude for year-
round production, though this can be adjusted for seasonal optimization.
7. Q: What is azimuth in solar terminology? ANSWER Azimuth is the
compass direction that a PV array faces, with 180° being true south in the
Northern Hemisphere (0° is north, 90° is east, 270° is west).
8. Q: What causes shading losses in PV systems? ANSWER Shading can be
caused by trees, buildings, chimneys, power lines, or other obstructions that
block sunlight from reaching the PV modules.
,9. Q: What is a sun path diagram used for? ANSWER A sun path diagram
shows the sun's trajectory across the sky throughout the year and is used to
identify potential shading issues at a site.
10. Q: What is the difference between true south and magnetic south?
ANSWER True south is geographic south (180° azimuth), while magnetic south
is where a compass points, which varies by location due to magnetic
declination.
11. Q: What is diffuse radiation? ANSWER Diffuse radiation is sunlight that
has been scattered by molecules and particles in the atmosphere before reaching
Earth's surface.
12. Q: What is direct (beam) radiation? ANSWER Direct radiation is
sunlight that travels in a straight line from the sun to the PV array without being
scattered or reflected.
13. Q: What is global horizontal irradiance (GHI)? ANSWER GHI is the
total solar radiation received on a horizontal surface, including both direct and
diffuse radiation.
14. Q: What is plane of array (POA) irradiance? ANSWER POA irradiance
is the total solar radiation striking the surface of a tilted PV array, which is the
most relevant measurement for PV system performance.
15. Q: What is the solar window? ANSWER The solar window is the
unobstructed area of sky through which sunlight can reach a PV array between
9 AM and 3 PM solar time throughout the year.
PV Cell, Module, and Array Basics
16. Q: What is the photovoltaic effect? ANSWER The photovoltaic effect is
the creation of voltage or electric current in a material upon exposure to light,
discovered by Edmond Becquerel in 1839.
17. Q: What are the two main types of semiconductor material in a PV
cell? ANSWER N-type (negative, with excess electrons) and P-type (positive,
with electron deficiencies or "holes").
18. Q: What is the most common material used in PV cells? ANSWER
Crystalline silicon (c-Si), which accounts for over 95% of the PV market.
19. Q: What is the difference between monocrystalline and polycrystalline
silicon? ANSWER Monocrystalline cells are made from single silicon crystals
(higher efficiency, 15-22%), while polycrystalline cells are made from multiple
silicon crystals (lower efficiency, 13-17%).
, 20. Q: What is a thin-film PV module? ANSWER Thin-film modules use
very thin layers of photovoltaic material deposited on substrates like glass or
metal, including technologies like CdTe, CIGS, and amorphous silicon.
21. Q: What is the typical voltage of a single crystalline silicon cell?
ANSWER A single crystalline silicon cell produces approximately 0.5-0.6 volts
under standard test conditions.
22. Q: How are PV cells connected to increase voltage? ANSWER PV cells
are connected in series to increase voltage. The voltages add while current
remains the same.
23. Q: How are PV cells connected to increase current? ANSWER PV cells
are connected in parallel to increase current. The currents add while voltage
remains the same.
24. Q: What is a PV module? ANSWER A PV module (or panel) is a
packaged, interconnected assembly of PV cells, typically containing 60, 72, or
other configurations of cells.
25. Q: What is a PV array? ANSWER A PV array is a mechanically and
electrically integrated installation of PV modules with a support structure.
26. Q: What is a PV string? ANSWER A PV string is a series connection of
PV modules that increases the voltage output.
27. Q: What is Standard Test Conditions (STC)? ANSWER STC defines
testing parameters: 1,000 W/m² irradiance, 25°C cell temperature, and air mass
1.5 spectrum, used for rating PV modules.
28. Q: What is NOCT (Nominal Operating Cell Temperature)? ANSWER
NOCT is the temperature a PV cell reaches under specific conditions: 800 W/m²
irradiance, 20°C ambient temperature, 1 m/s wind speed, and open-circuit
operation.
29. Q: What happens to PV module voltage as temperature increases?
ANSWER PV module voltage decreases as temperature increases. The
temperature coefficient for voltage is typically -0.3% to -0.5% per °C.
30. Q: What happens to PV module current as irradiance increases?
ANSWER PV module current increases proportionally with irradiance. If
irradiance doubles, current approximately doubles.
31. Q: What is Voc (open-circuit voltage)? ANSWER Voc is the maximum
voltage available from a PV module when no load is connected (open circuit
condition).
QUESTIONS AND ANSWERS - COMPREHENSIVE LATEST
VERSION (2026/2027)
1. Q: What is insolation? ANSWER Insolation is the amount of solar
radiation energy received on a given surface area during a given time, typically
measured in kWh/m²/day.
2. Q: What is the solar constant? ANSWER The solar constant is
approximately 1,367 W/m², representing the amount of incoming solar radiation
per unit area at the top of Earth's atmosphere.
3. Q: What is peak sun hours? ANSWER Peak sun hours represent the
equivalent number of hours per day when solar irradiance averages 1,000 W/m².
It's used to estimate solar energy production.
4. Q: What is the difference between irradiance and irradiation? ANSWER
Irradiance is the instantaneous power of solar radiation (W/m²), while
irradiation is the energy over time (Wh/m² or kWh/m²).
5. Q: What is albedo? ANSWER Albedo is the reflective property of a
surface, expressed as a percentage of sunlight reflected. Snow has high albedo
(~80%), while asphalt has low albedo (~5%).
6. Q: What is the optimal tilt angle for a PV array in most U.S. locations?
ANSWER Generally, the optimal tilt angle equals the site's latitude for year-
round production, though this can be adjusted for seasonal optimization.
7. Q: What is azimuth in solar terminology? ANSWER Azimuth is the
compass direction that a PV array faces, with 180° being true south in the
Northern Hemisphere (0° is north, 90° is east, 270° is west).
8. Q: What causes shading losses in PV systems? ANSWER Shading can be
caused by trees, buildings, chimneys, power lines, or other obstructions that
block sunlight from reaching the PV modules.
,9. Q: What is a sun path diagram used for? ANSWER A sun path diagram
shows the sun's trajectory across the sky throughout the year and is used to
identify potential shading issues at a site.
10. Q: What is the difference between true south and magnetic south?
ANSWER True south is geographic south (180° azimuth), while magnetic south
is where a compass points, which varies by location due to magnetic
declination.
11. Q: What is diffuse radiation? ANSWER Diffuse radiation is sunlight that
has been scattered by molecules and particles in the atmosphere before reaching
Earth's surface.
12. Q: What is direct (beam) radiation? ANSWER Direct radiation is
sunlight that travels in a straight line from the sun to the PV array without being
scattered or reflected.
13. Q: What is global horizontal irradiance (GHI)? ANSWER GHI is the
total solar radiation received on a horizontal surface, including both direct and
diffuse radiation.
14. Q: What is plane of array (POA) irradiance? ANSWER POA irradiance
is the total solar radiation striking the surface of a tilted PV array, which is the
most relevant measurement for PV system performance.
15. Q: What is the solar window? ANSWER The solar window is the
unobstructed area of sky through which sunlight can reach a PV array between
9 AM and 3 PM solar time throughout the year.
PV Cell, Module, and Array Basics
16. Q: What is the photovoltaic effect? ANSWER The photovoltaic effect is
the creation of voltage or electric current in a material upon exposure to light,
discovered by Edmond Becquerel in 1839.
17. Q: What are the two main types of semiconductor material in a PV
cell? ANSWER N-type (negative, with excess electrons) and P-type (positive,
with electron deficiencies or "holes").
18. Q: What is the most common material used in PV cells? ANSWER
Crystalline silicon (c-Si), which accounts for over 95% of the PV market.
19. Q: What is the difference between monocrystalline and polycrystalline
silicon? ANSWER Monocrystalline cells are made from single silicon crystals
(higher efficiency, 15-22%), while polycrystalline cells are made from multiple
silicon crystals (lower efficiency, 13-17%).
, 20. Q: What is a thin-film PV module? ANSWER Thin-film modules use
very thin layers of photovoltaic material deposited on substrates like glass or
metal, including technologies like CdTe, CIGS, and amorphous silicon.
21. Q: What is the typical voltage of a single crystalline silicon cell?
ANSWER A single crystalline silicon cell produces approximately 0.5-0.6 volts
under standard test conditions.
22. Q: How are PV cells connected to increase voltage? ANSWER PV cells
are connected in series to increase voltage. The voltages add while current
remains the same.
23. Q: How are PV cells connected to increase current? ANSWER PV cells
are connected in parallel to increase current. The currents add while voltage
remains the same.
24. Q: What is a PV module? ANSWER A PV module (or panel) is a
packaged, interconnected assembly of PV cells, typically containing 60, 72, or
other configurations of cells.
25. Q: What is a PV array? ANSWER A PV array is a mechanically and
electrically integrated installation of PV modules with a support structure.
26. Q: What is a PV string? ANSWER A PV string is a series connection of
PV modules that increases the voltage output.
27. Q: What is Standard Test Conditions (STC)? ANSWER STC defines
testing parameters: 1,000 W/m² irradiance, 25°C cell temperature, and air mass
1.5 spectrum, used for rating PV modules.
28. Q: What is NOCT (Nominal Operating Cell Temperature)? ANSWER
NOCT is the temperature a PV cell reaches under specific conditions: 800 W/m²
irradiance, 20°C ambient temperature, 1 m/s wind speed, and open-circuit
operation.
29. Q: What happens to PV module voltage as temperature increases?
ANSWER PV module voltage decreases as temperature increases. The
temperature coefficient for voltage is typically -0.3% to -0.5% per °C.
30. Q: What happens to PV module current as irradiance increases?
ANSWER PV module current increases proportionally with irradiance. If
irradiance doubles, current approximately doubles.
31. Q: What is Voc (open-circuit voltage)? ANSWER Voc is the maximum
voltage available from a PV module when no load is connected (open circuit
condition).
