Solar energy is one of the rising areas in the field of renewable energy due to its several advantages such as available in plenty, clean source of energy, safe for environment. Sun is the source of solar energy. The radiations emitted by sun are absorbed by solar cells and solar energy is produced through the process of photoelectric effect. These solar cells are the smallest component in solar photovoltaic system. These solar cells are connected in a well-arranged manner of series and parallel combination called as solar module. Many solar modules are connected to form a solar panel. A solar photovoltaic system consists of solar panels, solar charge controller, solar battery and solar inverter. The input is the solar radiations and output is the solar energy obtained in electrical form.
As solar panels are installed in open atmosphere the possibility of fault becomes dominant. The fault can occur in any component of solar photovoltaic system but the solar panels are more sensitive because they are exposed to direct contact of environment. When such type of faults occurs in any of the photovoltaic component, the performance of complete system decreases. Some of the common reasons are change in operating temperature, shade of tree, building or tower on solar panels, degradations and ageing effect in solar photovoltaic components, deposition of sulphur on terminals of solar batteries. All these effects decrease the efficiency and performance of complete solar photovoltaic system. Therefore, to monitor the changes occurred due to atmospheric conditions the remote condition monitoring is implemented now-a-days.
The remote condition monitoring provides direct online monitoring of the parameter values for different components of solar photovoltaic system. The change in output current, output voltage and output power along with variations in ambient temperature, component operating temperature, solar irradiance for solar panels can be monitored online. In case of solar battery, the state of charging and discharging, operating temperature, voltage and current profile can be monitored easily. The condition monitoring shows the graphs of different parameter values on the screen of monitoring system (personal computer).
This solar data i.e., current, voltage, power and temperature etc shown on the screen of monitoring system is stored in MS excel file format (.csv) in the monitoring system (personal computer). Storage of monitoring data provides as an additional advantage to view the graphs and values of stored solar data offline.
The transmission techniques allow to transfer the stored data from stored personal computer to the receiving point through several means but wireless transmission is more common. Some of commonly used wireless transmission techniques are zigbee, gsm due to their own advantages and applications and ability to work but has some limitations of time delay and data loss in the transmission of recorded data in video form. The QR codes being frequently used in transmission and sharing of video data improves the complexity of data transmission.
Monitoring, Transmission and Storing of Data Generated by Solar Photovoltaic System
Basically, there are two broad categories of solar photovoltaic generated system, they are off-grid (standalone) solar photovoltaic generated system and grid connected (online) solar photovoltaic generated system. The main components of a standalone solar photovoltaic generated system include:
• Solar panels
• Solar charge controller
• Solar battery
• Solar inverter
In case of online or grid connected solar photovoltaic generated system, the solar batteries are absent. To monitor the condition of solar components, wireless technique provides better results because of remote accessing through data loggers. The online variations in current, voltage, power, temperature and other atmospheric parameters like solar irradiance, humidity etc can be view on the screen of personal computer through remote condition monitoring. Zigbee and gsm are becoming more popular among other transmission due to their advantages. The solar data generated in personal computer is stored in MS excel (.csv format) from which graphs can be plotted offline means.
The block diagram shown in figure 1 represents the complete mechanism of monitoring and transmission of data generated by solar photovoltaic system.
Solar Photovoltaic Transmission with QR Codes
Now-a-days QR are becoming more popular as a method of communication, because of its several advantages and applications. Some the advantages of QR code are listed as:
• Fast scanning
• Smaller in size
• More capacity to store data
• It can support to many languages (numeric, alpha-numeric, kanji etc)
• Accessible through 360°
The maximum storage limit of a QR code for characters is 7089, for alphanumeric characters is 4296, for binary bytes is 2953 and for Kanji characters is 1817. Moreover, a QR code can store texts, contacts, url, shareable link, email etc so used in educational institutions, business, medical and security. QR code is a two-dimensional barcode having more storage capacity than one dimensional barcode because in QR code the data can be stored in both direction (horizontal and vertical). The basic construction of a QR code has two regions namely function pattern region and encoding region. The function pattern region contains finder, separator, timing patterns, alignment patterns while the information is stored in encoding section of a QR code. This stored information can be shared by providing a shareable link to QR code. The generated QR codes can be easily scanned through a QR code scanner installed in mobile phones to obtain the data contained within it.
Work Done
The work for the experiment is performed on a personal computer connected to the solar panels installed at the roof of Electrical Engineering Lab, Faculty of Engineering, Dayalbagh Educational Institute, Agra. The solar photovoltaic generating system is standalone having four solar panels, six long tubular batteries and one inverter as its components. The solar panels are installed in open atmosphere therefore the variations in output current, output voltage and output power with ambient temperature are monitored and stored in the personal computer having internet connectivity. These variations and graphs can be monitored online and stored in personal computer as MS excel sheet (.csv format). The offline data can be used to view the values of solar data stored in MS excel sheet (.csv format) and generate the graph from stored readings virtually but not really. Therefore, the concept of recording the variations of different parameter values and actual variations of graphs is introduced for better visualisation.
In this research work the online recording of solar data is performed with the help of google chrome to generate and provide a shareable link for the recorded solar data video file. This link is used to transfer the solar data when a QR code is scanned by a QR code scanning device. The figure 2 shows block diagram of the algorithm used in the experiment.
generated QR code for solar panel data
The name plate rating details of solar panels used in solar photovoltaic system is given below in table 1. The work done for transmission of solar panel photovoltaic data using QR code is divided into two sections:
A. Recording of solar photovoltaic data in PC:
The computer used to monitor the solar photovoltaic data with data logger installed on is connected with the internet and records the data using google chrome service with the help of webcam in video format (.webm). The recording is started and stopped manually by selecting the options mentioned in google chrome service. After the completing of the task the recording is automatically stored on google cloud storage with a shearable link associated with it. This link is provided for the sharing the recorded video file data using QR code.
The figure 3 to figure 6 shows snapshots of the recording of solar photovoltaic data on personal computer and shareable link ready for next phase of transmission.
B. Transmitting data using QR code:
The automatic generation of shareable link generated after completion of the video recording is attached to QR code through an android web application. The web application helps in creating and managing the accessing of solar photovoltaic panel data according to the requirements. The following figure 7 to figure 10 shows the QR code generated (QR code is watermarked for security reasons) and accessing the solar photovoltaic panel data using web application.
Proposed Strategy
The idea of transmission of solar photovoltaic panel data used in this paper can be extended to firstly store and transmit the more data with less space requirement. Secondly, the offline data transmission can also be extended to online real time if concept of variable QR codes is included in the research work. Solar data transmission through online real time with QR code has advantages of efficient storing, easy sharing, real time offline visualisation of variations in values and graphs and uniqueness in the area of solar photovoltaic.
Results & Discussions
The generated QR code is the successfully working for transmission of stored video file for the generated solar panel data. As explained earlier in the paper that the values of current, voltage and power are monitored online and stored in .csv format (comma separated value) using data logger but the new technique applied in this paper provides the real time video recording of the voltage, current and power in terms of values and graphs varying with time. The results obtained in the experiment give better visualization of the actual variations in voltage, current and power and helpful in performing detailed analysis when deep learning is required.
Conclusion
The solar photovoltaic generation system for solar panel monitors the voltage, current and power with data logger and record the values of voltage, current and power in .csv format. The new technique applied in this paper uses QR codes for storing the video recording to capture the real time variations in values and graphs for voltage, current and power. One of the biggest advantage is to store the recorded video file into QR code the tremendous reduction in size of video file from mega byte to kilo byte because the video file is stored in QR code in image form. The table 2 shows detail of recorded video file before and after conversion into QR code. The paper discusses the transmission of solar panel data using QR code for a small recording duration only but this novel technique can be implemented to integrate over other components of solar photovoltaic system with continuous recording for 24 hours a day and real time data can be transmitted easily to study better outcomes and better visualisation effects.
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