Panasonic
Solar Cells Handbook, Page 28
August 1998
9. SILICON SOLAR MODULES
High conversion efficiency and long-term reliability
9.1.
General Information
Crystal system silicon solar modules are attracting
attention through the world today primarily as high-
efficiency solar cells. This is because high-efficiency
solar modules are capable of converting the radiant
energy of sunlight directly into electrical energy which
is easy to use. Panasonic began marketing crystal silicon
solar modules and solar power supply systems in 1963.
We have continued to develop them for use in every
field, from the home to industry, improving their
performance and reliability while reducing their cost.
We have developed a variety of outdoor power supply
devices for observation, water discharge warning
stations and radio relay stations for dam control. We
have also developed solar clocks which have been
installed in more than 4,300 locations worldwide. Our
latest research and streamlined design systems are
highly regarded in many fields all over the world. This is
because our work is based on field data from over 10
years in a wide variety of solar battery utilization fields.
9.2.
Features
•
High in performance with a module using silicon
cells.
•
Superb reliability and long-lasting durability to meet
the operating conditions in various natural
environments.
9.3.
Applications
•
Independent power supply systems for radio relay
stations, measuring systems, etc.
•
Large-scale solar power generation systems linked
with commercial power.
9.4. Structure and Electricity Generation Principle of
Silicon Solar Cells
Solar cells use the photovoltaic effect of semiconductors
to convert light energy from the sun directly into
electrical energy. They do not store electricity. Most
silicon solar cells have a structure similar to that shown
in the diagram below. They consist of a sheet of silicon
called a P-type (approximately 0.4mm thick) with a
second, thinner (1-2
µ
m) layer called a N-type on top of
it.
The place where the P-type and N-type meet is called a
P-N junction. It constitutes the heart of the solar cell and
plays the most important role in the conversion of light
to electricity. The solar cell consists of the P-N junction
with electrodes on either side of it forming a grid, as
well as electrodes on the back surface. To briefly
explain the principle whereby electricity is generated,
light from the sun shines on the silicon and its energy is
absorbed by the crystal.
Electrons involved in forming the bonds between atoms
fly out from the crystalline framework as free electrons
bearing a negative charge. After the electrons have been
given off, a positive electron hole is formed. An
electrical field builds up inside the silicon present at the
P-N junction and the electrons are scattered to the N-
type silicon. A voltage is produced at both electrodes
and, if a load is connected to them, electrical power is
supplied to it.
9.5.
Specifications
Model No.
Structure
Absolute- maximum ratings
Electro-optical characteristics
Cell size
Number
of cells
Voltage
Dimensions
(mm)
Weight
(kg)
Operating
temperature
Topr
Storage
temperature
Tstg
Open--
Circuit
Voltage
Voc (V)
Optimum
Operating
voltage
Vpm (V)
Short--
circuit
current
Isc (A)
Optimum--
operating
current
1pm (A)
Maximum
power (W) P
max
Conversion
efficiency
(%)
W
L
H
min.
typ
BP-K36KS
100mm
36
DC12V
448
988
36
5.9
-40 ~ +90 °C -40 ~ +90 °C
21.5
16.9
3.35
3.20
51.4
54.1
15.0
BP-HK36K
100mm/2
445
535
36
3.2
20.7
16.7
1.55
1.44
21.6
24.0
13.0
BP-QK36H 100mm/4
350
340
30
2.0
21.0
16.8
0.78
0.68
11.7
13.0
16.0
BP-EK36
100mm/8
222
278
30
1.2
21.0
16.8
0.39
0.33
5.1
5.6
12.4
BP-STK36
100mm/16
187
201
30
0.7
20.8
16.6
0.19
0.17
2.5
2.8
12.4
Condition : Sunlight intensity at 1.0kW/m
2
Cell temperature at 25
°
C AM=1.5
Grid electrode ( - )
Anti-reflective coating
0.4mm
Current
n diffusion layer
P-type silicon substrate
Back surface
electrode (+)
1.5 m
+
