Description

CN3791 MPPT Solar Charger Module

The CN3791 MPPT Solar Charger is a compact solar charging module designed for charging a single-cell 3.7V lithium-ion battery from a compatible solar panel. It uses the CN3791 charging controller with maximum power point tracking (MPPT) to help extract available power from the solar input under changing light conditions.

This module is available in 6V, 9V and 12V input versions. Select the version that matches the nominal voltage of your solar panel. The 6V, 9V and 12V versions share the same product page, making it convenient to choose the right configuration for different solar-powered projects.

The charging output is designed for a single-cell Li-ion battery, with a nominal battery voltage of 3.7V and a full-charge voltage of 4.2V ±1%. The CN3791 uses a constant-current/constant-voltage charging process and supports automatic recharge and charging management functions.

MPPT Solar Charging

Unlike a basic solar charging board, the CN3791 controller incorporates maximum power point tracking. It tracks the solar panel’s available operating point as the input conditions change, helping the charging system make better use of available solar power.

This makes the module suitable for compact solar-powered electronics, portable projects and low-power outdoor applications where solar input can vary throughout the day.

6V, 9V and 12V Versions

Choose the appropriate module according to your solar panel’s nominal voltage:

• CN3791 6V — for compatible 6V nominal solar panels
• CN3791 9V — for compatible 9V nominal solar panels
• CN3791 12V — for compatible 12V nominal solar panels

Important: The module version should match the solar panel’s nominal voltage. A 9V version, for example, should be paired with a suitable 9V nominal solar panel.

Single-Cell Li-ion Battery Charging

The module is designed for charging one 3.7V nominal Li-ion/LiPo cell. Its regulated charging voltage is approximately 4.2V, making it suitable for single-cell rechargeable lithium battery applications.

The charging current is set by the current-sense circuit and depends on the specific board configuration, solar input and operating conditions. Some versions are specified for charging currents of up to 2A, while other board configurations are marketed up to 3A.

Compact Design for Solar Projects

With a compact PCB measuring approximately 45 × 20 × 9 mm, the module can be integrated into small solar-powered devices and DIY electronics projects.

It is useful for makers, electronics developers and engineers building compact systems that need to convert solar energy into a managed charging source for a single lithium battery.

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Key Features

• CN3791 MPPT solar charging controller
• Available in 6V / 9V / 12V input versions
• Designed for single-cell 3.7V Li-ion/LiPo batteries
• 4.2V ±1% constant-voltage charging
• MPPT function for solar power tracking
• Constant-current / constant-voltage charging
• Automatic recharge function
• Soft-start charging
• Deeply discharged battery conditioning
• Compact PCB design
• Suitable for DIY and embedded solar projects
• Approx. 45 × 20 × 9 mm module size

The CN3791 IC itself supports photovoltaic MPPT, single-cell Li-ion charging, automatic recharge, soft start and battery overvoltage protection.

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Technical Specifications

*Actual charging current depends on the board configuration, current-sense setting, solar input power, battery condition and thermal conditions.

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Applications

The CN3791 MPPT Solar Charger can be used in:

• Solar-powered IoT devices
• Outdoor sensor projects
• Remote monitoring systems
• DIY solar power projects
• Portable electronics
• Solar-powered data loggers
• Low-power embedded systems
• ESP32 and Arduino solar projects
• Remote wireless sensor nodes
• Battery-backed electronic devices
• Maker and electronics development projects

For example, the module can be evaluated in solar-powered sensor nodes, remote LoRa devices and other compact embedded projects where a single Li-ion cell is used as the energy-storage source.

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Important Notes

1. Choose the correct input version.
Select the 6V, 9V or 12V version according to the nominal voltage of your solar panel.

2. This module is designed for one lithium battery cell.
It is intended for a single-cell 3.7V Li-ion/LiPo battery, with a 4.2V full-charge voltage.

3. Charging current is not always the maximum rated value.
Actual charging current depends on solar power, battery condition, current-setting components and thermal conditions.

4. Please confirm the battery and solar-panel specifications before use.

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FAQ

Q1: What is the CN3791 MPPT Solar Charger used for?

It is designed to charge a single-cell 3.7V Li-ion/LiPo battery from a compatible solar panel while using MPPT technology to track available solar power.

Q2: What solar panel voltage should I choose?

Choose the module version according to the solar panel’s nominal voltage. The available versions are 6V, 9V and 12V.

Q3: Can this module charge a 3.7V Li-ion battery?

Yes. The module is designed for a single-cell Li-ion battery with a nominal voltage of 3.7V and a full-charge voltage of approximately 4.2V.

Q4: What is the output charging voltage?

The regulated charging voltage is 4.2V ±1% for a single-cell lithium battery.

Q5: Does the CN3791 support MPPT?

Yes. MPPT, or Maximum Power Point Tracking, is one of the main functions of the CN3791 controller and allows the charger to track the available power from a photovoltaic input.

Q6: Can I use the 12V version with a 6V solar panel?

It is recommended to select the module version that matches the nominal voltage of your solar panel rather than mixing the versions.

Q7: Is this module suitable for Arduino or ESP32 projects?

It can be used in compatible Arduino, ESP32 and other embedded projects where a suitable solar panel and single-cell Li-ion battery are required.

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Learn More

Want to see how this module works? Watch this tutorial video and learn how to connect and use it in your DIY project.