In this project, we use  ESP32 microcontroller which collects the data from the moisture, electrical conductivity, temperature, pH and NPK sensors. The ESP32 can use the sensor data to perform calculations and make decisions based on the data. 

The NPK sensor is connected to a Modbus(MAX 485) which is typically used to transmit signals from instrumentation and control devices back to the controller or data gathering system, for example a system that measures temperature and humidity and communicates the results to a computer.

A rechargeable battery is used to power the microcontroller and the sensors. In order to charge the battery, a solar panel and a charge controller is attached to it.

A charge controller regulates the flow of electrical current from solar panels to a battery or load, preventing overcharging and over-discharging, improving efficiency, increasing safety, optimizing performance and facilitating easy integration in solar panel-based applications.

If the voltage from the power source is not stable, a DC-DC converter is used to regulate the voltage to the required level for the ESP32. This can help to ensure stable operation of the microcontroller and prevent damage to the ESP32 or other components in the system.

The data containing sensor values from the cloud server is accessible via a web application through a mobile phone or computer.