Analyzing the Tropical Environmental Impact for Photovoltaic Performance Using NI LabVIEW and NI CompactRIO

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"NI LabVIEW and CompactRIO proved to be the best approach for analyzing the tropical environmental impact of solar photovoltaic performance. The ruggedness and modularity of CompactRIO made it the most suitable platform for our application."

- M. Effendy Ya’acob, Universiti Putra Malaysia

The Challenge:
Designing a real-time, synchronized monitoring system for tropical environmental elements including radiation, temperature, wind, humidity, light intensity, and rain.

The Solution:
Using NI LabVIEW to integrate the parameters and CompactRIO to capture the measurements, log the data, monitor the conditions, and visually analyze the data from various sensors in real-time and synchronized mode.

Author(s):
M. Effendy Ya’acob - Universiti Putra Malaysia
Hashim Hizam - Institute of Advanced Technology
Sheikh Ezaiddin Sheikh Mohd. Mustaffa - Virtual Instrument & System Innovation Sdn Bhd

Various developing countries in the world view renewable energy sources as an inevitable necessity to reduce greenhouse gas emissions and dependence on fossil fuel energy. The main source of energy for electricity generation in Malaysia comes from fossil fuels, which greatly constrains the fossil fuel supply and contributes to adverse effects on the environment. For these reasons, the Malaysian government is working toward attaining energy independence and promoting efficient use of renewable energy resources.

One of the main sources of renewable energy in a tropical climate such as Malaysia is solar photovoltaic energy. Photovoltaic (PV) technology harvests abundant, free sunlight to produce electricity via photonic effect. Some PV-based projects developed in Malaysia are in remote areas off-grid. One of the questions in the initial design stage of the PV systems is how much power the PV systems can generate, which usually reflects the entire PV system configuration without guarantee.

Field Setup

We set up a 10 kWp PV pilot plant based on a memorandum of understanding agreement between Universiti Putra Malaysia and Sichuan Zhonghan Solar Power Co. The pilot plant comprises three types of PV generator systems, rated 1 kWp each, and other supporting hardware as follows:

  • Six units of concentrating PV (CPV) generator systems
  • Two units of tracking-flat PV (TF) generator systems
  • Two units of fixed-flat PV (FF) generator systems
  • Stevens Met Station One weather station
  • Apogee Instruments pyranometer
  • Xylem Global Water rain bucket
  • PHOTASGARD AHKF light intensity sensor
  • Type K thermocouple installed on top of and under the PV modules

We connected all 10 units of PV generators to three Aurora inverter systems with the capacity of 2 x 3.6 kW and 6.0 kW for grid-tied operation. The sudden drop in I-V curve reflected the decrease in energy generation for specific durations, and most researchers claim this condition is due to the shading of sun radiation toward the PV surface. This research explores other influential factors such as ambient temperature, light intensity, wind cooling, and humidity that could contribute to the sudden drop in PV energy generation. These factors are especially important to the conditions in tropical weather locations.

DAQ and Monitoring System Setup

Figure 1 shows the solar PV monitoring system. We placed sensors with various signals near the PV plant to measure solar radiation, ambient temperature, light intensity, rain, wind cooling effect, and humidity. Due to the modularity of CompactRIO, we can easily integrate signals such as RS485 serial, current (4 to 20 mA), and high voltage into a single platform for data logging and streaming. Additionally, we can capture the power generated from the PV panels and the surface temperature of the PV and synchronize it with the environment data.

We programmed the CompactRIO module to automatically measure and log data in real time, normally from 7:00 a.m. until 7:00 p.m. every day. The system operates in a stand-alone mode and can constantly stream data to a PC connected to the CompactRIO module.

Results

We designed a host program using LabVIEW to monitor data in real time and analyze the data in offline mode (see Figure 2). The program captures three main features of thermocouple data (10 segments), environmental data (six segments), and PV generation data (23 segments times three inverter inputs) in real-time mode. From the system setup and data-monitoring process flow, we can individually view the data from each six-parameter sensor in real time and record it in a database (.tdms format) for the following research outcomes:

  • Real-time CPV monitoring for energy performance and environmental assessment in Malaysia
  • Thermal impact study of PV generator energy performance based on wind cooling and humidity impact in tropical climate weather conditions
  • Nominal operating-surface temperature modeling based on ambient and cell temperature for PV module efficiency
  • Light intensity correlation with radiation level for three types of PV generator systems
  • Short study of rain (m3) effect in Malaysian tropical climate weather conditions for examining the suitability of PV system generation

The above research outcomes represent a new contribution of knowledge and are scheduled to be complete within one year of data monitoring and analysis. Due to the modularity of the CompactRIO hardware and the power of LabVIEW, we can expand and improve the system in the future. We plan to add web monitoring to the system, along with viewing results via an Android-based platform. With this feature, researchers can monitor the data through a web browser from anywhere. We will add financial analysis to the reporting system to highlight the PV FiT rates recently endorsed by the Malaysian Parliament. We plan to use the LabVIEW Datalogging and Supervisory Control Module to professionally present the research outcomes.

Currently, we use CompactRIO only for the monitoring system. We may extend the function of the CompactRIO portion to control CPV system tracking, which would simplify the system because it would use just one platform to complete a solar station system.

Conclusion

NI LabVIEW and CompactRIO proved to be the best approach for analyzing the tropical environmental impact of solar photovoltaic performance. The ruggedness and modularity of CompactRIO made it the most suitable platform for our application. With the wide range of CompactRIO modules available, we easily integrated most of the sensors.

We used LabVIEW and CompactRIO for data synchronization, which is the most crucial portion in our research because we need to study and analyze the relationship between the I-V curve and the environmental data. We developed the software in a short period of time due to the simplicity of LabVIEW because researchers can easily understand the programming flow, even without programming knowledge.

We plan to explore using the solar PV application to study whether the technology is the best energy source for Malaysia. We can expand and modify the system we created whenever the research approach changes, which will cost us less money and time compared to using traditional instruments.

Author Information:
M. Effendy Ya’acob
Universiti Putra Malaysia
MPM, SERDANG, SELANGOR
43400
Malaysia
Tel: 603-89466258
Fax: 603-86567099
fendyupm@gmail.com

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