Conrad 19 47 51 Mode D'emploi page 4

The following number of solar cells are required, roughly, for a charging connection with
rechargeable batteries:
1 NiMH rechargeable batteries 5 solar cells 6 NiMH rechargeable batteries
2 NiMH rechargeable batteries 8 solar cells 10 NiMH rechargeable batteries 32 solar cells
3 NiMH rechargeable batteries 12 solar cells 1 lead rechargeable battery 6 V 18 solar cells
4 NiMH rechargeable batteries 16 solar cells 1 lead rechargeable battery 12 V 36 solar cells
5 NiMH rechargeable batteries 20 solar cells
If it is necessary to bridge periods of bad lighting, further solar cells will need to be
included. However, a charging controller is always recommended.
Size and Power
The power of solar cells depends on their size. Fractions of solar cells are not defective, they
only have a lower power. The following table presents the size and the potential average current
for silicon solar cells:
Rectangular
50 x 50 mm 440 mA
70 x 70 mm 1.2 A
100 x 100 mm 1.4 A
Installation and Connection
The individual solar cells are connected to each other by soldered fittings. Flexible copper con-
ductors are perfectly suitable for this.
Silicon, however, is very heat sensitive and will be destroyed by excessive heating. Soldering,
therefore, should only be done fast and quickly with a high-performance soldering tip (>50 W).
The maximum soldering temperature is 250°C!
If the joint does not work the first time, let the solar cell cool down before making an another
attempt to solder.
The edge of solar cells must not be soldered, since the two P-N layers are very
close to each other here and a short circuit can arise easily. Always use the pre-
pared soldering spots on the cells.
Scratches on the light-reactive layer must be completely avoided.
First of all, tin the soldering spots on the solar cell and the connecting wire. Carefully hold the
connecting wire with the copper-bit on the soldering area on the solar cell until the solder has liq-
uefied. The soldering process has to be done quickly, since the metal contacts on the solar cell
can dissolve in the solder within short time.
Try not apply pressure on the solar cell when soldering, since it can break easily. Inflexible con-
nection lines or external assembly parts, such as return protective diodes, should not be sol-
dered directly on to the solar cell. There is the danger of it breaking, even at a very low mechan-
ical stress.
Examples of Use
The following connection examples show you the most popular uses for small solar cells.
Light dependent operation without rechargeable battery
Many applications do not need energy storage. These are mostly used for decoration or only
when the sun shines. These are, for example, mini solar revolving stages or small fans with spe-
cial solar motors. The motors will only be supplied with voltage if there is sufficient light reaching
the solar panel. The solar panel, however, has to be constructed according to the power require-
ments of the device. The device is directly connected with the solar panel.
The connection principle is as follows:
Light dependent operation with rechargeable battery
The most applications utilise the solar energy in order to charge and to buffer self-contained
devices and installations with built-in rechargeable batteries. The advantage of these installa-
tions is their operational reliability even in the dark. However, in order to be able to charge in the
built-in rechargeable batteries via the solar panels, reliably and safely, further assembly parts are
necessary to protect the rechargeable battery.
There are differences concerning use with conventional NiMH round cells, as they are built into
smaller devices, such as solar garden lights etc, and the more powerful lead rechargeable bat-
teries for solar lanterns or construction site illumination.
When using lead rechargeable batteries the maintenance-free lead-gel version is to be
preferred, because it easier and less hazardous to handle. Furthermore, the use of a
solar charging controller is recommended.
Round (diameter)
50 mm 400 mA
76 mm 1.2 A
100 mm 2.1 A
Charging connection for NiMH round cells
To limit the voltage and the current, a diode (e.g. 1N4148
max. 100 mA) and an appropriate multiplier are required.
24 solar cells NiMH rechargeable batteries are sensitive to too high a
charging current and thus, it has to be limited.
The rechargeable battery buffers the power supply to the
device in bad light and stores the excess solar energy on
good lighting conditions (charging).
Charging connection for lead rechargeable batteries (Pb)
As return protection, a diode (e.g. 1N4001 up to max. 1 A or
1N5400 up to 3 A) is required.
Lead rechargeable batteries are sensitive to too high a
charging current. These, however, are determined by the
number of cells in the solar panel.
The rechargeable battery buffers the power supply to the
device in bad light and stores the excess solar energy on
good lighting conditions (charging).
Installation Notes
For mounting individual solar cells double-sided adhesive soft-tape is best. The solar cells are
to be arranged so they do not touch each other.
In outdoor areas, a protective cover is necessary, since the solar cells can be soiled by dirty rain,
causing a loss of performance.
The solar panel should be aligned at 90 degrees to the sun for the best performance. A sun-
tracking allows for longer use of the solar energy.
Maintenance and Cleaning
Regularly clean the surface, and the protective cover of the solar cell, respectively, in order to
ensure the best performance.
Do not use scouring, chemical or aggressive cleaning agents such as benzene, alcohol or such
like. These might damage the surface. Furthermore, the fumes are hazardous to your health and
are explosive. Moreover, you should not use sharp-edged tools, screwdrivers or metal brushes
or suchlike for cleaning.
Use a soft, anti-static dry brush to clean the surface.
Should questions arise concerning the use of the solar cells, feel free to contact
our technical support at the following phone number:
Conrad Electronic SE, Klaus-Conrad-Str. 2, 92530 Wernberg,
Tel. No. 01 80 / 5 31 21 18
Disposal
Electronic products are raw material and do not belong in the household waste. When the device
has reached the end of its service life, please dispose of it, according to the current statutory
requirements, at your local collecting site.
© Copyright 2009 by Conrad Electronic SE.
These operating instructions are a publication by Conrad Electronic SE, Klaus-Conrad-Str. 1, D-92240
Hirschau (www.conrad.com).
All rights including translation reserved. Reproduction by any method, e.g. photocopy, microfilming, or
the capture in electronic data processing systems require the prior written approval by the editor.
Reprinting, also in part, is prohibited.
These operating instructions represent the technical status at the time of printing. Changes in
technology and equipment reserved.