The WSSs (wireless sensor systems) concept is applied to implement an uninterrupted solar energy surveillance system in this work. The completed system is comprised of three major sub-systems that include a charging sub-system, a control sub-system and a display sub-system. Based on several transmission standards, including Bluetooth, Wifi and Zigbee capability combined with wireless transmission techniques, the proposed surveillance system is designed for monitoring a solar energy system. The performance of the simulated WSSs is evaluated using statistical report results. The proposed surveillance system can be fully extended to several different kinds of applications, such as, health care and environmental inspection. The experimental measurement results significantly show that channel fading over the propagation channel dominates the developed system performance.
WSSs (wireless sensor systems) have recently acquired an important role based on several real world application advantages such as low cost, easy establishment, selforganizing capacity and wide deployment for experimental research or real world practical applications. WSSs infrastructure has spread widely in various human life applications such as health care, automotive control, military command, communications and surveillance [1, 2]. Thus, study of the issues in each WSS protocol layer has gradually become a new research trend. These research areas include power consumption networking topology, signal processing, environmental monitoring deployment, transmission Media, etc. It is known that the greater the number of sensor nodes in the network the more precise the results provided to the BS (base station). However, in order to reduce the number of parameters for system performance, decreasing the number of sensor nodes to the optimal number is a good method. The mobility sensors is also an important point that can be applied to solve the coverage hole problem in WSSs [3,4]. Combining WNSs with RFID (radio frequency identification) devices is another recent study issue. For example, they can be combined together to solve surveillance issues [5,6]. Traditionally, wired transmission is the normal technique applied in energy monitoring. Wired communication was applied in monitoring the solar energy with project results reported in [7,8]. The system parameters in solar energy systems include the current, voltage and photovoltaic transformation power. Numerous publications have addressed these issues. Authors in [
Green energy applications are gradually achieving an important position in industry development due to the shortage of renewable energy. Certainly, the issue of efficiency promotion in solar system to complete energy transformation becomes relatively very important. The requirement for a wireless surveillance system for “looking at” a charging system is necessary. This paper proposes a fresh idea to implement an uninterrupted solar surveillance system with a radio system. The proposed monitoring system is an ubiquitous system, i.e., it can be deployed at any location where a solar system is established. This system is designed to be initially established as a prototype model that can be commercialized after implementation and the measurements are completed. The measurement results of the implemented monitoring system provide useful results for the solar energy parameters to the operator who may not reside at the site via Internet protocol communication systems. The measurements are held at the campus around Dayeh University located in Central Taiwan at a 2.2 acre site [
The organization of this paper is as follows. Following the introduction section, the system implementation architecture is described in Section 2. The implementation results are shown in Section 3. Section 4 draws the study conclusions.
The proposed solar energy monitoring system has three sub-systems, including the charging sub-system, the controlling sub-system and display sub-system, as illustrated in
The charging sub-system gathers energy through the solar cells, that is, the energy will be charged by the solar cell (photovoltaic) system and the energy will be stored in a long consuming battery. Back-up charging will be provided by the city power system if the energy cannot be maintained at a threshold value by the solar system.
To maintain the system capable of running non-interrupted, certain signals will be captured through the system nodes utilizing RFID (radio frequency identification) techniques. The system is presented in
The controlling sub-system, as shown in
The A/D (analog to digital) converter samples, quantizes and codes the received data. A cost effective matching micro processor in the A/D device ADC0804, which
is a serial product from Intersil Company with 8 bits precision, is chosen for the converter in this implementation. The ADC0804 specifications can be found in its data sheet [
The core sub-system control techniques constrained by the micro-controller or micro-process in charge of all arithmetic and logic operations. Based on the usual reasons for choosing a micro processor, e.g., multi-functional, simple designing, low cost and easy to acquire the chip packaged and numbered “AT89C51 PC24” from the @ATMEL company has become the candidate for this sub-system [
where SMOD denotes the internal TIMER model type of 89C51, represents the crystal oscillator frequency, is the baud rate in the communication port. For example, the internal timer 1, , will become as
when 9600 and model 0 timer baud rate are selected. Several important pin assignments are described as follows. The pin number P3.0 and P3.1 of 89C51 PORT3 are assigned as the communicating to and receiving function from the RF module, respectively. On the other hand, P3.0 and P3.1 are correspondingly connected to the TX and RX of the RF module and the P3.2 and P3.3 of PORT3 are two pins for accepting external interruption. The 8 pins P0.0 to P0.7 of PORT0 are designated connecting to an aligned 8 LEDs for error monitoring. The data bits (DB7 to DB0) coming out from the A/D device ADC0804 are arranged in contact with P1.7 to PT1.0 of 89C51 PORT 1. There are 3 connectors P2.0, P2.1, P2.2 of PORT2 which are assigned to periodically (adjustable) absorb the sampled data from 3 reedy relays (DIA050000, , defined in the data sheet [
Finally, the wireless transmission scenario is established using a 433 MHz RF module equipped with transmission distance capability of 500 meters without obstacles. The overall specification can be checked at the Web page of [
At this stage a script programmed with @Visual Basic software are applied to all functions for displaying the subsystems [
The total system is shown in
For evaluating the lifetime of any sensor nodes deployed in the WSS environment some conditions are taken into account in the integrated sub-systems. All consumed energy is supported by the charging sub-system.
The prototype system and simulated implementation are finished using universal PC boards. The full integrated system is shown in
The results from the implementation were completed as illustrated with experimental measurements. The RF modules, which can be alternatively replaced with Bluetooth, were adopted to transmit the necessary solar energy system information wirelessly. The WSS concept was also applied in the data gathering implementation from different places where solar energy systems could be installed. To avoid the severe shadowing effect from different transmission protocols such as ZigBee, GPRS, and WiMax, these technologies will be tested in the future in a suitable environment. The RFID techniques can be fused into the implementation for secure purposes. At the Dayeh university campus we adopted two experimental deployments, which were set up with different RF transmission modules, 433 MHz and 928 MHz. The simulated solar energy system and the monitoring system were placed at the front door of Dayeh University and inside the Lab room, respectively. The distance between these two places was about 200 meters. The solar voltages with full and non-full loder are measured, also the battery voltage. During the interval 12:00 to 17:00 PM. The
experiment exhibited a large amount of channel fading, which included large scale fading (huge academy building, big tree), and small scale fading (pedestrians). Because the class was dismissed at the noon time 12:00 to PM 12:30 interval, the inturruptions were caused mostly by people moving around the experimental area. The detail envirnment can look for the Web page of the Dayeh university [
The author would like to thank the anonymous reviewers and the editor for their helpful comments that considerably improved the quality of this paper.