Solar PV Based Mobile Battery Charger
- lms editor
- Aug 5
- 6 min read
Solar PV Based Mobile Battery Charger
A Solar PV Based Mobile Battery Charger converts energy from a solar panel into regulated charging power for a mobile lithium-ion battery. This MATLAB/Simulink model demonstrates solar-power extraction, DC–DC conversion, battery-charge control and real-time monitoring of voltage, current, power and state of charge.
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
Solar-powered charging is a practical way to reduce dependence on conventional electricity and support portable charging in locations where grid supply is limited.
The developed system uses:
Solar PV Based Mobile Battery Charger
A configurable solar PV array
A P&O MPPT algorithm
A DC–DC buck converter
A battery-charge protection controller
A 5 V, 6000 mAh lithium-ion battery
Measurement blocks for PV and battery parameters
The model also allows users to compare how different solar-panel ratings affect charging current and battery state of charge.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The complete charging system transfers power through the following path:
Solar PV Array → P&O MPPT Controller → PWM Generator → Buck Converter → Lithium-Ion Battery
Main components
Component | Function |
Solar PV array | Generates DC power from solar radiation |
P&O MPPT controller | Extracts the maximum available PV power |
PWM generator | Produces switching pulses for the converter |
Buck converter | Reduces the PV voltage to the battery-charging level |
Battery controller | Enables or disables charging according to battery conditions |
Lithium-ion battery | Stores the electrical energy |
Measurement system | Displays voltage, current, power and state of charge |
𝐒𝐨𝐥𝐚𝐫 𝐏𝐚𝐧𝐞𝐥 𝐂𝐨𝐧𝐟𝐢𝐠𝐮𝐫𝐚𝐭𝐢𝐨𝐧
A single PV module in the model has a rated power of approximately 9 W. The total solar power can be increased by connecting additional modules in parallel.
Parallel strings | Approximate PV power | Purpose |
1 | 9 W | Low-power charging analysis |
2 | 18 W | Charging close to 20 W |
3 | 27 W | Medium charging-power analysis |
5 | 45 W | Faster battery-charging analysis |
Increasing the number of parallel strings increases the available PV current while maintaining approximately the same operating voltage.
𝐌𝐚𝐢𝐧 𝐒𝐲𝐬𝐭𝐞𝐦 𝐏𝐚𝐫𝐚𝐦𝐞𝐭𝐞𝐫𝐬
Parameter | Value |
Single PV-module power | 9 W |
PV-module voltage | Approximately 12 V |
Maximum current of one module | Approximately 0.75 A |
Solar irradiance | 1000 W/m² |
Cell temperature | 25°C |
Battery nominal voltage | 5 V |
Battery capacity | 6000 mAh |
Initial battery state of charge | 50% |
Battery operating-voltage range | Approximately 3.75–5.8 V |
Simulation duration | 60 seconds |
Converter type | DC–DC buck converter |
MPPT method | Perturb and Observe |
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
1. Solar-power generation
The PV array produces DC voltage and current according to:
Solar irradiance
Cell temperature
Number of parallel modules
Connected battery load
Converter operating point
For a single 9 W module, the PV voltage is approximately 12 V, while the current is around 0.72–0.75 A under rated conditions.
2. Maximum-power extraction
The PV voltage and current are measured continuously. These signals are supplied to the P&O MPPT controller, which adjusts the converter duty cycle to operate the panel near its maximum-power point.
3. Voltage reduction
The solar-panel voltage is higher than the battery voltage. Therefore, a buck converter reduces the PV-side voltage to a level suitable for charging the 5 V battery.
4. Battery charging
The converter supplies controlled charging current to the lithium-ion battery. In the model, a negative battery-current value indicates that power is entering the battery and the battery is charging.
5. Battery monitoring
The model continuously monitors:
Battery voltage
Charging current
Battery power
State of charge
Maximum charging-voltage condition
Charging is permitted only when the battery remains within the specified voltage and state-of-charge limits.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
P&O MPPT control
The Perturb and Observe algorithm determines whether the operating point is moving toward or away from the maximum-power point.
The controller performs the following actions:
Measures PV voltage and current
Calculates PV power
Observes changes in power and voltage
Increases or decreases the duty cycle
Tracks the available maximum PV power
Sends the final duty-cycle command to the PWM generator
This method is simple, widely used and suitable for demonstrating solar-energy tracking in MATLAB/Simulink.
Battery-charge control
The battery controller checks two primary conditions:
Battery state of charge must remain below its maximum limit
Battery voltage must remain within the permitted charging range
When both conditions are satisfied, the MPPT-generated command is passed to the converter. When a battery limit is reached, charging is restricted or disabled.
𝐃𝐂–𝐃𝐂 𝐁𝐮𝐜𝐤 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The buck converter acts as the power-conditioning stage between the PV panel and the battery.
Its main functions are:
Reducing the PV voltage
Regulating the battery-charging voltage
Controlling the charging current
Transferring maximum available solar power
Protecting the battery from unsuitable charging conditions
The converter contains a controlled semiconductor switch, diode, inductor and output capacitor.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
Case 1: 9 W solar panel
With one PV module:
Output parameter | Approximate result |
PV voltage | 12 V |
PV current | 0.72–0.75 A |
PV power | Approximately 9 W |
Battery voltage | Approximately 5.4 V |
Battery current | Negative during charging |
Charging behaviour | Slow state-of-charge increase |
The 9 W configuration provides a comparatively low charging current. Therefore, the battery state of charge increases gradually.
Case 2: 45 W solar panel
With five modules connected in parallel:
Output parameter | Approximate result |
PV voltage | Approximately 12 V |
PV current | Approximately 3.8 A |
PV power | Approximately 43–45 W |
Battery voltage | Approximately 5.5 V |
Charging current | Approximately −6 to −7 A in the simulation |
State-of-charge behaviour | Faster increase |
The higher PV rating supplies more current to the converter, resulting in a steeper battery state-of-charge curve.
Comparison of charging performance
Parameter | 9 W PV system | 45 W PV system |
Number of parallel modules | 1 | 5 |
Available PV current | Low | High |
Charging current | Lower | Higher |
State-of-charge slope | Gradual | Steeper |
Relative charging speed | Slow | Fast |
Suitable use | Basic low-power study | Higher-power charging study |
The simulation indicates that the battery state of charge can increase by approximately 1% within 30 seconds under the higher-power case. This result represents the behaviour of the selected simulation parameters and battery model. Practical charging time will depend on converter losses, battery limits, thermal conditions, solar irradiance and the actual charging profile.
𝐌𝐨𝐧𝐢𝐭𝐨𝐫𝐞𝐝 𝐎𝐮𝐭𝐩𝐮𝐭𝐬
The model displays important electrical and battery variables in graphical form.
PV-side outputs
PV voltage
PV current
PV power
Tracked maximum power
Irradiance
Cell temperature
Battery-side outputs
Battery voltage
Charging current
State of charge
Battery power
Charging-status response
These waveforms make it easy to study the relationship between available solar power and battery-charging performance.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
Adjustable solar-panel rating from approximately 9 W to 45 W
Parallel PV-module configuration
P&O MPPT implementation
Controlled DC–DC buck conversion
Battery voltage and state-of-charge protection
5 V, 6000 mAh lithium-ion battery model
Real-time PV voltage, current and power monitoring
Battery voltage, current and state-of-charge analysis
Comparison of low- and high-power charging cases
Simple MATLAB/Simulink structure suitable for learning and testing
𝐀𝐝𝐯𝐚𝐧𝐭𝐚𝐠𝐞𝐬
Uses clean and renewable solar energy
Demonstrates direct PV-to-battery power conversion
Supports different solar-panel power ratings
Improves PV utilisation through MPPT
Provides controlled charging through a buck converter
Helps users understand charging-current direction
Makes battery state-of-charge behaviour easy to observe
Offers a clear platform for converter and controller analysis
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This model is useful for studying:
Solar-powered mobile charging systems
Portable renewable-energy chargers
Small lithium-ion battery chargers
PV-fed DC–DC converters
MPPT algorithm performance
Battery state-of-charge estimation
Solar-panel sizing
Off-grid charging systems
Power-electronics control
Renewable-energy laboratory demonstrations
𝐋𝐞𝐚𝐫𝐧𝐢𝐧𝐠 𝐎𝐮𝐭𝐜𝐨𝐦𝐞𝐬
By analysing this model, users can understand:
How PV power changes with array size
Why parallel panels increase available current
How the P&O MPPT algorithm tracks solar power
How a buck converter regulates charging voltage
Why battery current becomes negative during charging
How charging current affects the state-of-charge slope
How battery protection conditions control converter operation
How to compare charging performance under different PV ratings
𝐏𝐫𝐚𝐜𝐭𝐢𝐜𝐚𝐥 𝐂𝐨𝐧𝐬𝐢𝐝𝐞𝐫𝐚𝐭𝐢𝐨𝐧𝐬
Simulation results should not be interpreted as guaranteed hardware charging times. A practical charger must also consider:
Battery-manufacturer charging limits
Constant-current and constant-voltage charging stages
Converter efficiency
Switching and conduction losses
Battery temperature
Solar-irradiance variation
Cell balancing
Overcurrent protection
Overvoltage protection
Reverse-current protection
The selected battery current and voltage limits must always match the actual battery specification.
𝐅𝐫𝐞𝐪𝐮𝐞𝐧𝐭𝐥𝐲 𝐀𝐬𝐤𝐞𝐝 𝐐𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬
What is the purpose of the MPPT controller?
The MPPT controller adjusts the converter duty cycle so that the solar panel operates near its maximum available power point.
Why is a buck converter used?
The PV-panel voltage is approximately 12 V, while the battery voltage is around 5 V. The buck converter reduces and regulates the voltage for battery charging.
Why is the battery current negative?
The sign depends on the measurement direction used in the battery model. A negative value indicates that current is flowing into the battery during charging.
Can the PV rating be changed?
Yes. The total PV rating can be modified by changing the number of parallel strings.
Does a larger solar panel charge the battery faster?
A higher-rated PV array can provide more charging current under suitable conditions. This generally increases the battery state-of-charge rate, provided the battery and converter can safely accept the current.
What battery is used in the model?
The model uses a 5 V, 6000 mAh lithium-ion battery with an initial state of charge of 50%.
What parameters can be observed?
Users can observe PV voltage, PV current, PV power, battery voltage, charging current and state of charge.
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The Solar PV Based Mobile Battery Charger model demonstrates how solar energy can be efficiently converted into controlled charging power for a lithium-ion battery. The system combines an adjustable PV array, P&O MPPT, PWM control, a DC–DC buck converter and battery-protection logic.
The comparison between 9 W and 45 W PV configurations clearly shows that higher available solar power produces greater charging current and a faster increase in battery state of charge. The model is useful for students, researchers and engineers who want to understand solar-power extraction, converter operation, battery charging and state-of-charge analysis in MATLAB/Simulink.
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