I. Project Overview
1.1 Introduction
The greenhouse industry is rapidly expanding, and people are becoming more conscious of their health, which means that greenhouses must provide an optimal growth environment to enhance the quality of agricultural products. This paper presents a multi-functional intelligent monitoring system for solar-powered agricultural greenhouses based on GSM technology. The system is powered by solar energy, which supplies electricity to the microcontroller unit (MCU). It allows users to set ideal environmental parameters for different types of plants within the greenhouse. The system continuously monitors real-time environmental data—such as temperature, humidity, and light intensity—and displays it on a liquid crystal display (LCD) module. If any parameter deviates from the set values, the alarm system is triggered, and a message is sent to the greenhouse manager via the GSM module. Additionally, the system can automatically perform actions such as turning lights on or off, opening or closing doors, watering, and adjusting roller blinds. This intelligent system is expected to play a significant role in future agricultural practices, particularly in greenhouse farming.
1.2 Project Background / Motivation
Over the past two decades, China has invested heavily in the development of agriculture, with greenhouses being one of the most important infrastructure projects. As a modern agricultural technique, greenhouses have overcome traditional limitations related to climate, region, and environment, significantly increasing crop yields. However, with rising living standards, people are now more concerned about the quality of agricultural products. While greenhouse production has improved, current management still relies largely on manual experience or basic single-parameter control systems. This lack of automation makes it difficult to accurately regulate the optimal growing conditions for various crops. Greenhouses today are not highly automated, leading to inefficiencies in production. Among the key factors affecting plant growth, light, temperature, and humidity are essential. An intelligent monitoring system is therefore crucial for achieving efficient and automated greenhouse operations. Such a system should collect, analyze, and process environmental data, trigger alarms when necessary, and enable intelligent control to ensure that crops grow in the best possible conditions.
II. Demand Analysis
2.1 Functional Requirements
The system is powered by solar energy and allows users to set the required levels of illumination, temperature, and humidity for different plants. It continuously collects environmental data and displays it on an LCD screen. If the measured values exceed or fall below the set thresholds, the system automatically triggers an alarm and performs actions such as switching lights, opening doors, irrigation, or adjusting roller blinds. It also sends alert messages to the greenhouse manager via the GSM module. This system is suitable for both large-scale greenhouse farming and small-scale cultivation of specialty plants. The system architecture is illustrated in Figure 2.1:
Figure 2.1 System Architecture
2.2 Performance Requirements
The system is powered by solar energy, with a humidity measurement range of 20% to 90% RH and a temperature measurement range of 0°C to +50°C. The signal transmission distance exceeds 20 meters, and all collected data is displayed on the LCD. The MCU controls the GSM module to send parameter updates to the manager, ensuring real-time communication and efficient monitoring.
III. Program Design
3.1 System Function Realization Principle
As shown in the following figure, the system consists of several major modules: a solar power supply module, a sensor module (including illuminance, temperature, and humidity sensors), a GSM module, an intelligent control module (for controlling lights, doors, irrigation, and roller blinds), a keyboard module, and an LCD display module. The system's hardware block diagram is illustrated in Figure 3.1:
Figure 3.1 System hardware block diagram
3.1.1 Solar Power Supply Module
Solar energy is a clean, renewable, and increasingly popular energy source. One of its key applications is converting sunlight into electrical energy using solar cells. The solar power supply module in this system uses 5W polycrystalline silicon solar panels produced by Shenzhen Wanjiahao Solar Energy Co., Ltd. These panels have a maximum voltage of 18V and an efficiency of approximately 12%. Compared to monocrystalline silicon panels, polycrystalline panels are cheaper to produce, require less energy during manufacturing, and offer a lower overall cost, making them widely adopted in various applications.
3.1.2 Sensor Module
Illuminance Sensor: Illumination is a critical factor in plant growth. In facility agriculture, the importance of measuring light levels has grown significantly. Most existing systems use silicon photovoltaic cells for illumination detection. However, photodiodes offer better performance, including higher bandwidth, lower cost, and a more linear relationship between photocurrent and illuminance. They are widely used in optical isolators and data transmission devices. Therefore, this system is designed around the characteristics of photodiodes to create a simple yet effective illumination detection circuit.
Temperature and Humidity Sensor: Temperature and humidity are also vital for plant growth. This system employs the DHT11 digital temperature and humidity sensor, which provides calibrated digital outputs. It combines a resistive humidity sensor and an NTC temperature sensor with a high-performance 8-bit microcontroller. The DHT11 is known for its reliability, stability, fast response time, and strong anti-interference capabilities. Each sensor is calibrated in a precision humidity chamber and stores calibration coefficients in OTP memory. The single-wire interface simplifies integration, and the sensor’s small size and low power consumption make it ideal for demanding applications.
3.1.3 GSM Module
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