11:34 PM Chapter 6 - Energy Conversion - Solar Energy |
Chapter 6
-
introduction
-
advantages and drawbacks
(disadvantages)
-
solar cell or photo voltaic cell
o construction
o theory of operation
-
symbols
-
circuit used
-
definitions
Introduction
Solar energy is an conventional renewable energy .
Solar energy appears to be most important energy in the future .
Advantages
1- it's free from cost
2- it's inexhaustible غير منتهية
3- it's completely pollution free
Drawbacks (disadvantages)
1- energy density per unit area is very law
2- it's available for any part of the day
3- it's cloudy and hazy atmosphere reduce energy received
Q. write short account in photo voltaic cell. خلية كهروضوئية
When
P.N Junction of solar cell illuminated ( electron – hole – pairs ) are
generated , an electric field is established near the P.N junction , which
leads to development of potential across the junction , many of electrons are
pulled across the junction by the force of electron field contribute to the
current in the cell
The
voltage of the cell is proportional to intensity or incident light , the
voltage may be as 0.6 volt .
Symbols
The Circuit used :
** Definitions :-
1- photo voltaic cell : (P.V.cell) :
It's the smallest part which can convert light to electricity .
2- Modules :-
It's a group of solar cells connected in series and in parallel to give high voltage and current .
3- panel :-
It's a group of modules connected in series and parallel to give high voltage and high current .
4- array :-
It's a group of panels connected in series and in parallel .
** characteristics of photo voltaic cell ( Is.c , Vo.c ) .
* The relation between the current and the voltage of the solar cell is shown in fig (1)
* and this curve depends on :-
1- The spectrum of the light (wave length)
2- Quantity of incident light .
3- all the temperature of the circuit cells .
* the photo voltaic cells produces electric current within 1 Amp and potential 0.5 volt .
- when connecting n1 of solar cells in series the voltages becomes open circuit .
n1 -- جهد
n2 -- تيار
and in connecting n2 of solar cells in parallel , current becomes short circuit .
- Is.c => " is the short circuit current of the solar cell or max current can be produced from the solar cell at incident of certain amount of light on it and in this case the potential is zero "
- Vo.c => " is the open circuit voltage of the solar cell
or max voltage can be produced at the terminal of the solar cell at incident of
certain amount of light on it and in this case the current is zero "
Basic P.V system for power generation :-
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