Hi everyone. 1
Welcome back to PV 2
solar energy course into the last section. 3
We already discussed that electric behavior of solar cell and light and dark and we discovered that 4
the idea of solar cell may be modeled by a current source in parallel with a diode to understand 5
mean parameter of solar cell. 6
We are going to simplify this circuit by eliminating the shunt resistant and series resistant as shown 7
in the right figure. 8
The diode current can be model as Id equal to. 9
I note which is that saturated current or reverse saturated current or leakage saturated 10
current times exponential of Q which is electronic charge times the voltage. 11
Above all this meant constant time Zeldin preacher all minus one mean that our current will be equal 12
to I for two of the current source minus diet current which is equal. 13
I knew times exponential of electric charge times the voltage over both these men cause sometimes temperature 14
minus one we can rule this equation as a function of current involved the only variable Z is the voltage. 15
So when the voltage is change the current will be changing. 16
As shown in the circuit 17
in this plot we are going to discuss the external parameter zapped it through minus a light to electricity 18
conversion efficiency of idea a solar cell let's start with open circuit voltage. 19
Let's consider a z z determinant of an illuminated solar cell are not connected. 20
In this situation it's called an open circuit an open circuit the solar cell doesn't produce any current 21
and slowly produce a voltage. 22
This full dish is called the open circuit voltage zoom voltage is easily recognized. 23
Is that all you V. 24
Plot by intersection of I V curve with Zella Rosenthal axis corresponding to the current equal to zero 25
as shown in this figure we can derive a simple equation for open circuit voltage of an idea. 26
Solar Cell 27
other open circuit condition. 28
The current is equal to zero. 29
If we solve this equation we arrive at a simple expression for the open circuit voltage. 30
It is linear with both these men constant times temperature divided boy. 31
The charge of electron and its linear with the natural logarithm of the ratio between the photo Qana 32
and the linkage current the loss 1 33
equation shows that the amount circuit floater depends on several barometer firstly the open circuit 34
voltage depends on two preacher 35
secondly the equation shows that ends up food the current density is increased the open circuit voltage 36
is increased as well. 37
This means that by increasing the irradiation or in other words by shining the light on solar cell zob 38
in circuit voltage can be increased. 39
Also this equation 1 First I suggest Z open circuit voltage increase with temperature. 40
This is not a case the latest torrent or on a note of diet strongly depend on the temperature means 41
the highest in preacher the larger Lake is traversed since you're 80. 42
Current and smaller over the circuit voltage will be mean there are always circuit voltage depends on 43
other factors. 44
Such as the band again of absorber material as an amount of dubbing of Z don't leave that wanted host 45
the material Xilai generated condensed and anti-immigration and we already understood Z him preacher 46
is inversely proportional to the open circuit voltage we already understood the open circuit voltage 47
is inversely proportional to sit in preacher the second parameter we are going to discuss they is short 48
circuit current if we short circuit all terminal of Z solar cell Z eliminate the solar cell will slowly 49
produce a current and will produce no voltage this current density is called the Short Circuit Ga. 50
This 51
the short circuit current can easily be recognized in the I.V. care as well it is the intersection between 52
the vertical line corresponding to zero voltage and so on V curve 53
we can derive a simple equation forces a short circuit garden density or shorter type of an ideal solar 54
cell by using again as the expression of the joy of your relationship 55
ie equal to eye food to current minus i.e. die you when the vote is equal to zero mean the auto short 56
circuit will be equal to I photographed means if we take a voltage equal to zero. 57
The short circuit current is if were the two therefore two current 58
the short circuit current debates on several fact like say in single light it just or the number of 59
floaters falling on Z solar cell. 60
Second thing is this big turn of the light 61
sensing is optical properties or absorption coefficient so let's think is collection probability. 62
Now we already understood the meaning of short circuit count and the open circuit voltage all open circuit 63
voltage is the maximum voltage on the solar cell and short circuit term is the maximum con can be produced 64
by solar cell tomorrow we are going to introduce you to an important properties of solar cell which 65
is maximum power point which is the main principle of the maximum our point trucker so see you in the 66
next to block.