Designing of MPPT Solar Charge Controller using Arduino

Overview
In this project, we are going to build an Arduino-based MPPT Solar Charge Controller for charging a 12V lead-acid battery. MPPT stands for Maximum Power Point Tracking. A nominal 12V solar panel normally operates at a voltage higher than the battery charging voltage. Instead of simply pulling the panel down to the battery voltage, an MPPT controller uses a DC-DC buck converter and continuously adjusts its operating point so that the panel can deliver power close to its maximum power point. The buck converter then trades the higher panel voltage for higher charging current while conserving power as closely as possible, apart from normal conversion losses.
In this article, we will first understand solar charge controllers and MPPT operation, and then design the complete schematic around an Arduino Nano, an IR2104 half-bridge gate driver, a synchronous buck power stage, voltage and current sensing, load control, protection devices, and an onboard 5V supply. The Arduino measures solar-panel voltage, solar current, solar power and battery voltage, while a 20×4 I2C LCD displays the charger state, estimated state of charge (SOC), PWM duty cycle and load status.
The controller is intended for a 12V lead-acid battery and a solar panel of about 50W, with the panel open-circuit voltage kept within the design limit of approximately 25V. The power stage is designed for currents up to about 5A; the present firmware does not implement a closed-loop 5A charge-current limiter. We will also cover component selection, protection, calibration and practical testing of the controller.
Revision Note (August 2026):
The schematic, PCB and firmware in this article have been updated. Some older comments or media may refer to previous revisions, so use the latest schematic, PCB files and source code provided here.
Bill of Materials
We will use the following components in our project to build an Arduino Based MPPT Solar Charge Controller. You can purchase all the components from the given links.
No.
Component
Designator
Quantity
Manufacturer Part

Capacitor 100nF
C1,C6,C9,C11

CC1H104MC1FD3F6C10MF

Capacitor 10uF
C2,C3,C7,C10

NXA 50V10 5*11

Capacitor 100uF
C4

NXB 50V100 8*11.5

Capacitor 220uF
C5

GR227M010E11RR0VH4FP0

Capacitor 100nF
C8,C12

CT4-0805B104K500F3

MBR1045
D1

MBR1045

1N4148
D2,D5

1N4148

P6KE20CA
D3

P6KE20CA

MBR1060
D4

MBR1060

Fuse Holder
FUSE1,FUSE2,FUSE3

178.6164.0001

Female Header
H1

PPPC041LFBN-RC

Terminal Block
J1,J2,J3

1729128

Inductor 33uH, 8.4A
L1

2200HT-330-V-RC

LED Red
LED1

WP7113SURDK

LED Green
LED2

WP7113GD

LED Blue
LED3

WP7113SF4BT-P22

IRFZ44ZPBF
Q1,Q2,Q4

IRFZ44ZPBF

IRLZ44NPBF
Q3

IRLZ44NPBF

Resistor 220Ω
R1,R11,R12,R14,R15,R17

MFR0W4F2200A50

Resistor 100kΩ
R2,R9

MFR0W4F1003A50

Resistor 470kΩ
R3

CFR0W4J0474A50

Resistor 1kΩ
R4

MFR0W4F1001A50

Resistor 20kΩ
R5,R10

MFR0W4F2002A50

Resistor 10kΩ
R6,R13,R16

MFR0W4F1002A50

Resistor 22Ω
R7,R8

MFR0W4F220JA50

Push Button Switch
SW1,SW2

KH-6X6X6H-TJ

ACS712 Module
U1

ACS712 Module

Buck Converter Module
U2

MP1584

IR2104PBF
U3

IR2104PBF

ARDUINO_NANO
U4

ARDUINO_NANO

MXP6KE36CA
ZD1

MXP6KE36CA

Fuse

Littelfuse 028707.5PXCN
What is a Solar Charge Controller?
A solar charge controller is an electronic device that regulates the flow of electrical current from a solar panel to a battery or a bank of batteries.
It controls how the battery is charged and can also disconnect or limit charging when required by the selected charging algorithm. A properly designed controller also prevents reverse current from the battery toward the solar panel at night and includes protection against abnormal electrical conditions. It is a critical component in a battery-based solar power system. Solar irradiance can be measured using
Pyranometer Sensor
Types of Charge Controllers
Every solar panel system that has batteries needs a charge controller. Its purpose is to regulate and control the power coming from the solar panels to the batteries to prolong the health of the batteries.
There are three types of charge controllers:
Simple on-off Controller (ON OFF)
Pulse Width Modulation Controller (PWM)
Maximum Power Point tracking controller (MPPT)
On-off controllers are very simple devices. All they do is detect the voltage of the battery bank and turn on or off the power.
Pulse width modulation controllers will charge a little bit faster than on-off controllers, and then they taper down the voltage as the battery gets full. When the battery is full, the controller switches to a float charging profile, which basically just keeps a trickle of current coming into the battery to keep it from discharging. PWM controllers will extend the life of a battery over simple on-off controllers.
Maximum Power Point Tracking Controllers (MPPT)
An MPPT (Maximum Power Point Tracking) charge controller regulates battery charging while trying to operate the solar panel near the point on its current-voltage curve where panel power is highest. It does this by changing the duty cycle of a DC-DC converter, which changes the electrical load seen by the panel. This lets the panel operate near its maximum-power voltage while the converter supplies the voltage and current required by the battery.
MPPT controllers are more sophisticated than simple on-off or PWM controllers because they actively search for the operating point that produces the highest available panel power. In a buck-type MPPT charger, the higher panel voltage can be converted into additional charging current at the lower battery voltage, subject to converter efficiency and current limits.
A nominal 12V panel commonly has a maximum-power voltage around the high-teens and an open-circuit voltage around 20V or more, while a 12V lead-acid battery is normally charged in roughly the 13V to 14V range depending on charge stage, temperature and battery specification. This voltage difference is why a buck-converter MPPT architecture is useful.
Advantages & Disadvantages of MPPT Solar Charge Controller
An MPPT controller can make better use of the voltage difference between a solar panel and a battery, particularly when the panel maximum-power voltage is well above the battery voltage. Many commercial MPPT controllers also support higher PV input voltages, which can reduce cable current and wiring loss in larger systems. However, the allowable PV voltage is always limited by the particular controller. For this project, the PV open-circuit voltage should remain within the stated design limit rather than assuming that arbitrary series-connected panels can be used.
The main disadvantages are additional circuit complexity, switching losses, higher cost and the need for careful PCB layout and thermal design. Actual conversion efficiency depends on the input voltage, charging current, MOSFET and diode losses, inductor resistance, switching frequency and control algorithm; it should therefore be measured on the finished hardware rather than assumed from a generic percentage.
MPPT is especially useful when panel voltage varies significantly with temperature and irradiance. At very low irradiance the available panel power is small, so the benefit of tracking also becomes small and the controller may intentionally stop switching below a minimum-power threshold.
Designing of MPPT Solar Charge Controller using Arduino
Now let us design the MPPT Solar Charge Controller using an Arduino Nano. The design combines a 50kHz synchronous buck converter, voltage and current sensing, a gate-driver stage, load control, protection components and firmware-based MPPT control.
This project is designed with reference taken from
opengreenenergy
and
asmlektor
design. We have modified the design according to our requirements.
Features & Specifications
The charge controller has the following features:
Arduino Nano based MPPT co