How was the data logger made?

The Solar water heater LIVE Logger is built with OPEN SOURCE hardware and code.

The main microcontroller is an ESP8266 WiFi, accompanied by sensors such as:

  • DS18B20 for measuring the temperature inside the solar water heater boiler
  • DHT21 for measuring ambient temperature
  • LDR for measuring light intensity

The webcam image is transmitted by an ESP32-CAM connected to the internet.
The ESP8266 and ESP32-CAM are programmed using the ARDUINO IDE environment.

For data storage and presentation, PHP/MySQL, WordPress, Google Charts, etc. are used.

HARDWARE

ESP8266 Microcontroller

solar-water-heater-esp8266

The ESP8266 is an inexpensive and versatile Wi-Fi module widely used for IoT (Internet of Things) applications. It has built-in Wi-Fi, can be programmed in C or Lua, and supports multiple communication protocols such as HTTP and MQTT. It features a Tensilica L106 microcontroller running at 80 or 160 MHz and can connect with various sensors and devices via its GPIO pins. It is used for remote control and data collection in automation projects, smart homes, and other networking applications. This microcontroller is used by the SolarWaterHeater.Online project for data collection, chosen for its low cost and the wide availability of libraries and resources.

Waterproof DS18B20 Temperature Sensor

solar-water-heater-ds18b20

The DS18B20 is a high-accuracy digital temperature sensor communicating via the 1-Wire protocol. It can measure temperatures from -55°C to 125°C with an accuracy of ±0.5°C within the range of -10°C to 85°C. One key feature is the ability to connect many sensors on the same bus, thanks to the unique 64-bit address of each sensor. It is used in various applications such as ambient temperature measurement, liquid temperature, and temperature control systems. This sensor is suitable for measurements inside tanks due to its shape. It can be placed inside the electric thermostat pipe of the boiler and can measure over 100 degrees Celsius, which is necessary for our case. It is waterproof and can measure even in liquids, though that is not required here.

DHT21 Temperature and Humidity Sensor

solar-water-heater-dht21

The DHT21 (or AM2301) is a digital temperature and humidity sensor. It can measure temperature with ±0.5°C accuracy and relative humidity with ±3% accuracy. The sensor outputs data through a digital signal, making it ideal for use with microcontrollers like the ESP8266. It is commonly used in climate control applications such as smart HVAC systems, weather stations, and other environmental monitoring. From our experience and other projects, this sensor is recommended. It is reliable both in measurements and continuous operation.

LDR Light Intensity Sensor

solar-water-heater-ldr-sensor

The LDR (Light Dependent Resistor) or photoresistor is an analog sensor whose resistance changes according to the light intensity it receives. The more light it receives, the lower the resistance becomes, allowing measurement of ambient brightness. It is widely used in automatic lighting control, smart lamps, security systems, and other applications based on light detection. In the Solar LIVE project, it is mainly used for its reliable continuous operation rather than because there are better sensors related to brightness.

ESP32-CAM WiFi Module

solar-water-heater-esp32cam

The ESP32-CAM is a version of the ESP32 that includes a built-in camera and Wi-Fi, making it ideal for applications such as surveillance, smart cameras, and image recognition. Besides the dual-core ESP32 microcontroller, it has a microSD card slot for data and image storage. It supports resolution up to 2MP with the OV2640 camera that comes with it. It is popular in projects such as IP cameras, monitoring systems, and face detection due to its flexibility and wireless connectivity. On our website, it is used as a live webcam transmitting a new image every few minutes towards the solar water heater to visually verify sky conditions, complementing the light sensor (LDR).

SOFTWARE

This page refers to the SOFTWARE requirements for the SolarWaterHeater.Online project.
The programming language PHP and the database MySQL are two of the most popular technologies for developing dynamic websites and web applications. The combination of PHP and MySQL is common in applications like WordPress, Joomla, and other platforms, offering flexibility, speed, and ease of development.

In our case, the site is hosted on WordPress. For storing the data sent by the microcontroller, we used a MySQL database with PHP as the programming language that manages, processes, and displays the data on the site. Visualization is done through Google Charts.

PHP

solar-water-heater-php

PHP is a server-side programming language designed to create dynamic content and interact with databases. It is widely used for web and application development, allowing logic execution, content management, and dynamic web page

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