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Solar Demo Set
Item-No. 19 47 51
Intended Use
The Demo Set allows experimental trials concerning the topic power generation by solar ener-
gy. It demonstrates how solar cells function and their use and application in daily live. With suf-
ficient illumination the set generates a nonhazardous safe low-voltage. Touching the contacts
during use is totally harmless.
Always observe the safety notes included in these operating instructions.
Package Contents
Solar panel (max. 400 mA/0.45 V/DC)
Solar motor with propeller
3-colour demo panels
Safety Instructions and Hazard Warnings
Please read all of the operating instructions before using the product for the first
time; they contain important information about the correct operation.
• The warranty will be void in the event of damage caused by failure to observe these safety
instructions! We do not assume any liability for any consequential damage!
• Nor do we assume any liability for material and personal damage caused by improper use or
non-compliance with the safety instructions! The warranty will be void in such cases!
• Single solar cells can be easily broken by low mechanical loads. This will result in sharp and
pointed pieces. Therefore, be especially careful when children are around.
• When connecting multiple solar cells in series (construction of big panels) a voltage of > 75
V/DC (direct current) can be generated! Above this voltage it is possible to get a fatal electric
shock, if you touch the electrical conductors.
• Do not leave packing materials unattended. They may become dangerous playthings for chil-
dren.
• In commercial institutions, the accident prevention regulations of the Employer's Liability
Insurance Association for Electrical Systems and Operating Materials are to be observed.
• If you have doubts about how the equipment should be operated or how to safely connect it,
consult a trained technician.
• Handle the product with care. It can be damaged through impact, blows, or accidental drops,
even from a low height.
This device left the manufacture's factory in a safe and perfect condition.
We kindly request the user to observe the safety instructions and warnings contained in the
enclosed operating instructions so this condition is maintained and to ensure safe operation.
Please pay attention to the following symbols:
A triangle containing an exclamation mark, in these operating instructions, indicates
important information that has to be observed without fail.
The „hand" symbol is used to indicate where specific hints and information on handling
are given.
Solar Cells in Practice
Solar cells have been proven to be reliable for supplying power for installations and devices in
remote locations. It is recommended that solar cells are used when there is no mains supply is
available. There are also many possible areas of application for hobbies. For example, power-
ing small electrical devices such as radios, toys, watches, charging devices etc. and also for
wider leisure time use, gardening and camping activities.
Solar cells are available in different shapes (round, angular) and colours. These feature do not
influence the performance.
Individual solar cells have a plus pole (top side) and a minus pole (the whole bottom) and can
be connected in any order (soldered).
The solar cell is formed from silicon crystals. However, silicon is a very brittle material and breaks
easily at very low mechanical loads. Therefore it is very important to handle it with care.
Single solar cells generate a nominal voltage of about 0.5 V. The power depends on the size of
the cell.
In order to increase the voltage and power, multiple solar cells are combined into solar panels.
These are most often assembled on a frame with a cover in order to facilitate mounting.
Construction of a Solar Installation
www.conrad.com
A solar installation consists in the main of the following components:
1 Solar panel
Version 06/09
2 Charge controller or return protective
diode
3 Energy storage
4 Consumer
With sufficient illumination, the solar panel provides electrical power. A charging controller recog-
nises the ideal time for the operation of the solar panel and controls the charging current for the
energy storage (rechargeable battery) highly effective.
In simple systems, only one return protective diode is normally included. A diode only allows the
current to travel in one direction. This prevents the stored energy from being discharged via the
solar cell when there is not sufficient illumination.
Power curve for solar cells (at </= 25°C)
If too much current is drawn, the voltage will break down (poor effi-
ciency), if too little current is drawn, the installation and the poten-
tial energy is not utilised (poor efficiency).
When there is no load, a solar cell provides a maximum voltage of
approx. 0.55 V/DC that decreases with increasing load. The max-
imum power is reached with a cell voltage of 0.45 V.
The ambient temperature has a significant influence on the performance. The following values
show the effect of a temperature rise exceeding 25°C per solar cell:
Voltage decreases by approx. 2 mV/°C
Current decreases by approx. 25 µA/°C
Efficiency decreases by approx. 0.3%/°C
The nominal data for a solar cell normally refers to an ambient temperature of
</= 25°C and a solar power of 1000 W/m
cover and and the sun is overhead. The solar panel should always be aligned at 90° to the sun,
in order to achieve the maximum energy generation.
Applications for Solar Cells
In order to use solar cells effectively in practice, the single cells are connected together to pro-
duce high-performance solar panels. For this three different methods are used. In all of them,
however, only the same type of solar cells (same size, type and power) should be used.
Series connection (increased voltage)
In series connection, the cells are connected consecutively from plus pole to minus pole. This
type of connection makes it possible to increase the voltage. Each extra cell increases the volt-
age by approx. 0.45 V. The current, however, remains at the value for a single solar cell.
Parallel connection (increased current)
In parallel connection, the cells are connected in parallel i.e. from plus pole to plus pole and
minus pole to minus pole. This type of connection makes it possible to increase the current. Each
extra cell increases the current. The voltage, however, remains at the single cell value.
Combination of series and parallel connection (increase in performance)
The best and most effective kind of connection is a combination of series and parallel connection.
In this, several series-panels are connected together to further parallel panels. This has the
advantage of both methods: Increase in voltage and current = increase in power.
All modern solar panels use a combination of both these kinds of connection.
In practice, solar panels are normally used in combination with an energy storage such as NiMH
or lead rechargeable batteries. Doing this balances the power fluctuations caused by changes
in light (clouds, bad weather, darkness etc.).
Solar cells are used as a power source to charge rechargeable batteries.
For lead rechargeable batteries (Pb), reckon with 6 solar cells per rechargeable battery cell (2V).
For round cell rechargeable batteries (1.2V), such as NiMH, 4-5 solar cells are used.
If a return protective diode is used, the voltage drop at the diode has to be balanced by a further
1-2 solar cells.
2
. This is reached in the summer when there is no cloud
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