The document discusses a photovoltaic battery charge regulator designed with a microcontroller, aimed at improving solar energy utilization in battery charging systems. It covers technical features such as charging capabilities, system efficiency, types of photovoltaic cells, and the design of the charge regulator for preventing battery damage. The study concludes that photovoltaic technology has reached a satisfactory level of efficiency and reliability, though it notes issues with module degradation in amorphous PV technology.

1. Battery Charge Regulator for a photovoltaic
Battery Charge Regulator for a photovoltaic
power system using microcontroller
power system using microcontroller
By
By
:
:
Raed Wa’el Ennab & Raja Sa’ed Anabtawi
Raed Wa’el Ennab & Raja Sa’ed Anabtawi
Supervised by :
Prof. Marwan Mahmoud

2. Introduction
Introduction
Since the beginning of the oil crises, which remarkably
Since the beginning of the oil crises, which remarkably
influenced power development programs all over the world,
influenced power development programs all over the world,
massive technological and research efforts are being
massive technological and research efforts are being
concentrated in the field of renewable energy resources.
concentrated in the field of renewable energy resources.
In the solar sector for electricity generation, greater
In the solar sector for electricity generation, greater
attention is being given to photovoltaic conversion.
attention is being given to photovoltaic conversion.

3. Features
Features
1- Charge any rechargeable battery 12V, 24V.
1- Charge any rechargeable battery 12V, 24V.
2- Supply any low dc load.
2- Supply any low dc load.
3- Solar-powered.
3- Solar-powered.
4- Displays charging status.
4- Displays charging status.
5- Polarity checking.
5- Polarity checking.
6- Current Limiting.
6- Current Limiting.

4. Advantages and Disadvantages
Advantages and Disadvantages
:
:
The advantages are
The advantages are
:
:
1
1
-
-
Renewable resource
Renewable resource
.
.
2
2
-
-
Silent
Silent
.
.
3
3
-
-
Non-polluting
Non-polluting
.
.
4
4
-
-
Little maintenance
Little maintenance
.
.
5
5
-
-
easy to install
easy to install
.
.
6
6
-
-
Reliability
Reliability
.
.
And the disadvantages are
And the disadvantages are
:
:
1
1
-
-
Very expensive. 2- No work at night
Very expensive. 2- No work at night
.
.

5. Block Diagram
Block Diagram
Solar Panel Regulator
Lead Acid
battery
PIC Load

6. Photovoltaic cells
:
In our design, the solar panels will function as a power
supply to our circuit. It will convert the sun radiation
to voltage and current.
types of photovoltaic cells
:
1
-
mono-crystal silicon
.
2
-
Polycrystal silicon
.
3
-
Amorphous silicon (thin film silicon)
.
Regulator
Battery
Solar
Panel
PIC Load

7. efficiency
Material
Material
level of efficiency in %
level of efficiency in %
production
production
Mono crystalline silicon
Mono crystalline silicon
14-17
14-17
Polycrystalline silicon
Polycrystalline silicon
13-15
13-15
Amorphous silicon
Amorphous silicon
5-7
5-7

8. number of cells
The output voltage of a module depends on the number of
cells connected in series. The module we used was 25 cell
connected in series.

9. solar cell I-V
characteristics

10. A Typical Current-Voltage
A Typical Current-Voltage
Curve for a Module at (85)c and
Curve for a Module at (85)c and
(25)
(25)
A Typical Current-Voltage
Curve for a Module at
(1000)W/m^2
&
(500)W/m^2

11. Photovoltaic Arrays
Photovoltaic Arrays
:
:
Series connection Parallel connection

12. Charge
Regulator
:
The solar charge regulator main task is to charge the battery
and to protect it from overcharging and deep discharging.
Deep discharging could also damage the battery
.
Kind of charge regulators
:
1
-
Simplest switch on/off regulators
.
2
-
PWM ( Pulse Width Modulation)
.
3
-
MPPT charge regulator (Maximum Power Point Tracking)
.
Regulator

13. 1
1
-
-
We are going to work on six-cell lead-acid batteries
We are going to work on six-cell lead-acid batteries
.
.
2
2
-
-
Voltage/cell 1.75-2.4 V
Voltage/cell 1.75-2.4 V
.
.
3
3
-
-
Battery charge
Battery charge
.
.
4
4
-
-
Battery efficiency
Battery efficiency
.
.
5
5
-
-
Minimum Voltage
Minimum Voltage
.
.
Lead acid
Battery
Regulator
Solar
panel
PIC Load
Lead Acid Battery

14. Lead acid battery
Lead acid battery
In our project, the circuit we built has two leds; red one
In our project, the circuit we built has two leds; red one
and green one.
and green one.

15. Circuitry

16. circuitry
+
S
-
S

17. Circuitry
Circuitry
• when the voltage is lower than 14.4 V the comparator (IC3)
when the voltage is lower than 14.4 V the comparator (IC3)
allows a high negative output signal to switch on the PNP
allows a high negative output signal to switch on the PNP
transistor (Q1)
transistor (Q1).
• During charging, the battery voltage increase until it reaches
the 14.4 V value. At this voltage, the transistor (Q1) will be
switched off.
• N1 and N2 from the IC4001 are utilized as pulse oscillators for
the purpose of testing.
• In this short period, transistor Q2 will be switched on, and a
current will flow from the emitter to the collector of Q2.

18. • Then the comparator (IC2) compares the battery voltage
Then the comparator (IC2) compares the battery voltage
with the open-circuit voltage of the solar generator
with the open-circuit voltage of the solar generator.
• The main objective of using the pulse generator is to
control the voltage of both the solar generator and the
battery continuously.
 The objective of the comparator (IC5) is to control the
battery voltage during the discharging mode

19. two MOSFET transistors were
two MOSFET transistors were
utilized instead of one
utilized instead of one
-
-
To make the prevention of the battery discharging via
To make the prevention of the battery discharging via
the solar generator as strong as possible
the solar generator as strong as possible
.
.
-
-
The temperature of the two transistors, due to the
The temperature of the two transistors, due to the
voltage drop across them, is divided equally between
voltage drop across them, is divided equally between
them
them
.
.
-
-
Increasing the reliability of the controller since one
Increasing the reliability of the controller since one
transistor can perform the task of the other in case of
transistor can perform the task of the other in case of
its failure
its failure
.
.
-
-
This arrangement protects the controller from failure
This arrangement protects the controller from failure
whether it is connected to the solar generator first or
whether it is connected to the solar generator first or
to battery
to battery
.
.

20. Features of The Locally developed
Features of The Locally developed
Battery Control Unit (BCU)
Battery Control Unit (BCU)
-
-
Protects battery against overcharging: the unit controls the
Protects battery against overcharging: the unit controls the
charging current via a regulated impulse, thus preventing
charging current via a regulated impulse, thus preventing
harmful overcharging
harmful overcharging
.
.
-
-
Protect the battery against deep discharging: the unit
Protect the battery against deep discharging: the unit
controls battery discharge by means of bistable load relay
controls battery discharge by means of bistable load relay
.
.
-
-
-
If the battery charge drops bellow a predetermined
If the battery charge drops bellow a predetermined
voltage threshold, the relay automatically disconnects the
voltage threshold, the relay automatically disconnects the
load, this is indicated by a red light- emitting diode (LED)
load, this is indicated by a red light- emitting diode (LED)
.
.
-
-
The unit is protected against battery reverse polarity via a
The unit is protected against battery reverse polarity via a
diode (D4)
diode (D4)
.
.

21. PIC
PIC

22. Flow chart
Flow chart
Read the
battery
Voltage
Read the
voltage fro
the
regulator
Out to the
battery
from the
regulator
Out to the
load from
the
Regulator

23. Here we used the DAC to convert the digital output from
Here we used the DAC to convert the digital output from
the PIC to Analog.
the PIC to Analog.

24. Results
Results

25. Results
Results
I-V Characteristic
At G=950 w/m2
Resistance
(ohm)
Current
(mA)
Voltage
(
V
)
0
401.7
0
10
384
1.92
20
379.2
3.85
30
370.1
5.12
40
365
6.02
50
360.3
6.9
60
353.5
7.5
70
352.2
8.61
80
351.4
10.4
90
350.8
11.3
100
305
15.4
>>
0
19.1

26. Results
Results
Fill factor and efficiency
Fill factor and efficiency
:
:
The Imp = 350 m A and the Vmp =15 volt
The Imp = 350 m A and the Vmp =15 volt
So the max power point = 15*.350= 5.25 watt
So the max power point = 15*.350= 5.25 watt
.
.
The fill Factor
The fill Factor
:
:
FF= (Imp*Vmp)/ (Is.c*Vo.c)
FF= (Imp*Vmp)/ (Is.c*Vo.c)
( =
( =
15
15
*
*
0.350
0.350
( /)
( /)
19
19
.*
.*
4
4
= )
= )
70%
70%
The efficiency
The efficiency
:
:
Eff= P.opt/ A.Ee
Eff= P.opt/ A.Ee
Eff=5.25/ 0.3*0.3*950 =6.1%
Eff=5.25/ 0.3*0.3*950 =6.1% All calculations are at G=950
w/m2

27. The results we got were:
The results we got were:
Vpv
(V)
Ipv
(mA)
Vbatt
(V)
Ibatt
(mA)
17.1
328
12.6
323
14.9
302
12.9
296
14.1
298
13.01
289.6
13.46
275
13.27
270

28. Problems we have faced
Problems we have faced
:
:

1
1
-
-
The output voltage was about 15 volts, and the PIC
The output voltage was about 15 volts, and the PIC
accept only 5 V maximum
accept only 5 V maximum
.
.

2
2
-
-
The radiation from the sun was different from day to
The radiation from the sun was different from day to
another
another
.
.
3
3
-
-
The wires we used first were the thin wires so when the
The wires we used first were the thin wires so when the
current passed these wires got hotter
current passed these wires got hotter
.
.

29. The applications for our
The applications for our
project
project

30. Conclusion and
Conclusion and
Recommendation
Recommendation
:
:
-From the technical and economical viewpoints, it can be said
-From the technical and economical viewpoints, it can be said
that the PV technology has attained an acceptable
that the PV technology has attained an acceptable
degree of operational efficiency and reliability
degree of operational efficiency and reliability.
-Module degradation seemed to be a problem in amorphous PV
technology.
-The tested amorphous PV module showed power
degradation between 16.4% and 39% at the end of the
first year testing period.
-if we have more time we could program the PIC with a
program that can drive a stepper motor and rotate
it as the max radiation from sun and that by using
photo sensors.