Elenco Deluxe Solar Educational Kit - Manual (Page 7)

7
CALCULATION AND FORMULATION
1W = 1000mW = 10 3 mW 1mW = 0.001W
1A = 1000mA = 10 3 mA 1mA = 0.001A
1V = 1000mV = 10 3 mV 1mV = 0.001V
P = WATT(W), E = VOLTAGE(V), I = CURRENT(A)
P = EI, I = , E =
EXAMPLE 1
CHART B, ITEM NO.11 SOLAR MUSICAL 4.5V 450mW
Calculate the current (I) and then determine the connecting system.
1. I =
2. I =
3. I =
4. I = 0.1A
5. I = 100mA
6. So a solar musical unit required 4.5V 100mA
7. Now we know the voltage is 4.5V and the current (I) is 100mA, then we have to determine
the system with connecting in series circuit.
8. Each row of solar cells output is:
Voc: 1.5V
±0.1V (each row)
Isc: 90mA
±10mA (each row)
See Figure 7, 8, 9, 12 & 32
9. We use the figure of 1.5V and 100mA for simple calculation.
10. We select 4.5V 100mA with increased voltage by connecting in-series circuit system.
11. To increase the voltage, connect the cells in series but the current (I) remains constant
(negative point connect to positive point).
To increase the voltage, formula as follows:
E total = E
1
+ E
2
+ E
3
e.g.:(E
1
)1.5V + (E
2
)1.5V + (E
3
)1.5V = 4.5V
I total = I
1
= I
2
= I
3
But the current (I) remains constant = 100mA
12. How many rows of solar cells are needed to make a solar panel work for a solar musical unit
of 4.5V 100mA:
Rows of cells =
= 3 rows of cells
So 3 rows cells x 1.5V = 4.5V
* In series connecting method, see Figure 9, 12 & 32
P
E
450mW
4.5V
0.450W
4.5V
Solar musical unit 4.5V
Each row of cells 1.5V
P
E P
I