Photovoltaics

Question 1

Energy

Answer 1

[J] Capacity for Work

Question 2

Work

Answer 2

[J] Macroscopic Motion of a System due to the action of a force

Question 3

Power

Answer 3

[W = J/s] Energy Flow

Question 4

Irradiance

Answer 4

[W/m^2] Power of electromagnetic radiation per area

Question 5

Spectral Irradiance

Answer 5

[W/m^2nm] Considers each freq. in the Spectrum

Question 6

Insolation

Answer 6

[kWh/m^2] Irradiance on a given surface in a given time interval

Question 7

Solar potential

Answer 7

[kWh/m^2] average daily insolation during the year

Question 8

Photovoltaic potential

Answer 8

[kWh/kW] average yearly energy production per 1 kW of installed PV Power

Question 9

Energy of Photon

Answer 9

characterised by eiterh wavelength in lambda or energy in eV

Question 10

Spectral Irradiance F

Answer 10

[W/m^2nm] Power density at a particular wavelength

Question 11

Power density of a blackbody M

Answer 11

M = sig*T^4
T= Surface Temp.
sig = Boltzmann constant

Question 12

Solar Constant

Answer 12

Io 1350 W/m^2

depends on applied spectrum

Question 13

Extraterrestrial Irradiance

Answer 13

Changes due to eccentricity in earths orbit

+- 3%

Question 14

Terrestrial Irradiance

Answer 14

Changes due to:
Atmosphere
Sun trajectories relative to Horizon ( due to axial tilt)

Question 15

Atmospheric Effects for PV Applications

Answer 15

• reduction of Irradiance due to absorption, scattering, reflection
• change in spectral content
• local variations in the atmosphere

Question 16

Air mass

Answer 16

represents the proportion of atmosphere that the light must pass trough

Question 17

Global Irradiance

Answer 17

I_hg = I_hb + I_hd + I_hr (Beam, Diffuse, Reflected)

usually measured hourly (Pyranometer)

Question 18

Atmospheric Influence

Answer 18

Considered by clearness indices K_g and K_d

Question 19

Solar Measurements

Answer 19

• typical mean year data for a location
• avg. daily, monthly or yearly solar insolation
• sunshine hours data

Question 20

Solar Time

Answer 20

LocalSolarTime (LST) and Local Time (LT) Noon LST is defined as Zenith
LT varies from LST due to timezones, eccentricity

Question 21

Local Standard Time Meridian

Answer 21

LSTM reference meridian for a particular timezone 15° * deltaT_gmt

Question 22

Equation of Time

Answer 22

EoT empirical equation that corrects for eccentricity and axial tilt

Question 23

Time correction Factor

Answer 23

Accounts for the variation of the LST within a given timezone due to longitude variations and incorporates EoT
TC = 4(Long-LSTM) + EoT

Question 24

Declination Angle

Answer 24

angular position of the sun at solar noon with respect to the plane of the equator. varies seasonally

Question 25

Utilization of terrestrial irradiance

Answer 25

1. Maximize irradiance on surface of PV Module - > single or two axis tracking system 2. Maximization of energy conversion process - > MPPT / efficient dc/dc and dc/ac converters

Question 26

Rated Power

Answer 26

Maximum power the system is capable of delivering. This is also called the nominal power

Question 27

Peak Power

Answer 27

This is the power a module delivers if subjected to a standard radiation (25 0C, AM-1.5) of 1kW/m².

Question 28

Cell Efficiency

Answer 28

Rate at which the semiconductor cell converts energy from radiation into electricity.

Question 29

Module Efficiency

Answer 29

As several cells are connected to form a module, there are additional losses stemming from the wiring. Note that there is no difference between cells and modules in thin-film technology.

Question 30

Capacity Factor

Answer 30

With respect to a specific installation, the capacity factor is the average power delivered over a year compared to the rated power.