Introduction to Photovoltaic Technology
Ridha Hamidi, Ph. D.
PV Cells, Modules, and Arrays
PV System Building Blocks
• The basic building
blocks for PV
systems include
cells, modules, and
arrays.
Boron, Silicon, Phosphorous
Semiconductors
• Semiconductor materials
with special electrical
properties can be made
by adding small
amounts of other
elements to silicon
crystals.
Photovoltaic Effect
• The photovoltaic effect produces free
electrons that must travel through
conductors in order to recombine with
electron voids, or “holes.”
PV Materials Efficiencies
• Various PV materials and technologies
produce different efficiencies.
20
Efficiency (%)
16
NREL
CuInSe2
CdTe
Amorphous silicon
(stabilized)
12
NREL
Univ. of So. Florida
BP Solar
EuroCIS
Boeing
Boeing
Univ. of So. FL
ARCO
Photon Energy
AMETEK
United Solar
Kodak
Boeing
Monosolar
8
Kodak
Boeing
Matsushita
Boeing
Univ. of Maine
ECD
The Best One-of-a-Kind Laboratory
Cell Efficiencies for Thin Films
(Standard Conditions)
4
0
1975
NREL
RCA
1980
1985
1990
1995
2000
2005
02658722
PV Cell Manufacturing Video
see also animation on
http://www.noutilitybill.com/
I-V Curve
• An I-V curve
illustrates the
electrical output
profile of a PV cell,
module, or array.
Maximum Power Point
• A power against
voltage curve
clearly shows the
maximum power
point.
Open-Circuit Voltage (Voc)
• Open-circuit
voltage is easily
measured with
test instruments.
Short-Circuit Current (Isc)
• Using in-line and
clamp-on
ammeters are two
methods of
measuring shortcircuit current.
Cell Efficiency
• Efficiency is a measure
of how effectively a PV
device converts solar
power to electrical
power.
Solar Irradiance Response
• Voltage increases
rapidly up to about 200
W/m2, and then is
almost constant.
Current increases
proportionally with
irradiance
Temperature Response
• Increasing cell
temperature
decreases voltage,
slightly increases
current, and results
in a net loss of
power.
I-V Curve Video
Junction Box
• A junction box on
the back of a
module provides a
protected location
for electrical
connections and
diodes.
Electrical Connections
• MC connectors
Series Connections
• PV cells or
modules are
typically connected
in series strings to
build voltage.
PV Devices in Series
• The overall I-V characteristics of a series
string are dependent on the similarity of
the current outputs of the individual
devices.
Parallel Connections
• Strings of PV cells or modules may be
connected in parallel to build current.
PV Devices in Parallel
• The overall I-V
characteristics of a
system of PV devices in
parallel are dependent
on the similarity of the
current outputs of the
individual devices.
01
23
45
6
87
111019
1123
1145
1176
1289
2201
2223
2245
2267
2389
3301
3323
3354
3367
3489
4401
4432
4445
4467
4589
5501
5523
5545
5567
5689
6610
6623
6645
6667
6798
777102
7734
7756
7787
8890
8812
8834
8856
8878
9990
9912
9934
965
Amps
Mismatching Modules
14.0
12.0
10.0
8.0
Sanyo HIT Power 180
Mitsubishi UD 180 MF5
6.0
Series
Parallel
4.0
2.0
0.0
Volts
Module Sizes and Shapes
• Modules are
available in several
sizes and shapes,
including squares,
rectangles,
triangles, flexible
units, and shingles.
Bypass Diodes
• Bypass diodes allow current to flow
around devices that develop an opencircuit or high-resistance condition.
Bypass Diodes Video
STC vs PTC
• Standard Test Conditions (STC)
– 1,000 W/m2
– AM1.5 solar spectral irradiance distribution
– 25°C cell or module temperature
• PVUSA Test Conditions (PTC)
– 1,000 W/m2
– 20°C ambient temperature
– 1m/s wind speed
• Silicon PV power varies by about -0.5% per °C
– PV module temperature is about 50°C under PTC
– Module PTC power rating is about 88% of the PV
module nameplate rating
CEC Rating
http://www.gosolarcalifornia.ca.gov/equipment/
Sharp 216 WATT
ND-216u1F
SANYO HIT Power 180
HIP-180BA19
Module Nameplates
• Module
nameplates must
include
performance
ratings for the
module and may
include other
information used to
design a PV
system.
Solar Marshal
Amorphous Silicon Thin Film Photovoltaic Panels
Electrical Characteristics
Building an Array
• Modules are added in series
to form strings or panels,
which are then combined in
parallel to form arrays.