However, solar energy generation is not without challenges. Like wind power, solar irradiance - the amount of sunlight available in a given region - can fluctuate significantly due to weather conditions, leading to variations in power output. These variations can disrupt power grids and make it difficult to consistently meet energy demands. Therefore, understanding how solar irradiance changes over time and across different locations is essential for determining the best sites for solar power plants.
In response to this need, a research team led by Specially Appointed Assistant Professor Hideaki Takenaka from the Center for Environmental Remote Sensing at Chiba University has conducted a comprehensive study to better understand solar irradiance across the Asia Pacific region. Their findings, published in the July 2024 issue of 'Solar Energy' and made available online on June 13, 2024, provide valuable insights into how solar irradiance varies in both space and time. The research team included Kalingga Titon Nur Ihsan and Atsushi Higuchi from Chiba University, as well as Anjar Dimara Sakti and Ketut Wikantika from the Institut Teknologi Bandung.
The study utilized data from the Japanese satellites Himawari-8 and Himawari-9, which capture high-resolution images of the Asia Pacific region. The researchers employed AMATERASS solar radiation data, which is derived from real-time analysis synchronized with geostationary satellite observations. Developed by Dr. Takenaka and his team, AMATERASS uses neural networks to perform high-speed radiative transfer calculations, allowing for accurate estimates of solar irradiance. This data, collected over 16 years and made publicly available by Chiba University's CEReS DAAC, has been downloaded over 186 million times and used in numerous research and national projects in Japan.
By analyzing solar irradiance data over a grid measuring 20 km by 20 km at ten-minute intervals, the researchers were able to estimate the variability of solar irradiance in both spatial and temporal terms. Their analysis revealed several key findings. For instance, they discovered that regions near the equator experience fewer fluctuations in solar irradiance over time compared to higher latitudes, primarily due to rain and cloud activity. Additionally, areas at higher elevations showed greater variability due to increased cloud activity. The Tibetan Plateau, in particular, exhibited significant seasonal changes in the "umbrella effect," a measure of how much solar energy is reflected back into space. "Our evaluations based on spatiotemporal data revealed characteristics that would've been impossible to achieve using a traditional approach that relies on simple long-term averages or TMY (Typical Meteorological Year) as a typical solar irradiance data," said Dr. Takenaka.
The research team also evaluated the performance of over 1,900 existing solar power plants using annual and seasonal data. They found that many of these plants experience suboptimal production from June to August due to the umbrella effect caused by clouds. This finding suggests that regions heavily affected by these conditions should not rely solely on solar power during these months.
Finally, the study explored the optimal configuration for future solar power plants. The researchers concluded that a more distributed approach to solar energy generation, involving smaller photovoltaic systems spread over a wide area, would be more effective at reducing rapid fluctuations in power output than large, centralized solar plants. "Based on the spatial and temporal characteristics of solar irradiance, we suggest that it should be possible to suppress rapid fluctuations in solar power generation output by distributing small photovoltaic systems over a wide area rather than relying on large solar power plants," Dr. Takenaka explained. "Worth noting, these conclusions come from weather and climate research, not an engineering perspective." Rooftop solar panels, which are becoming increasingly popular in many countries, could play a significant role in this strategy.
These findings will contribute to more effective planning for solar energy generation in the Asia Pacific region, supporting sustainable energy development and helping to combat climate change.
Research Report:Solar irradiance variability around Asia Pacific: Spatial and temporal perspective for active use of solar energy
Related Links
Center for Environmental Remote Sensing, Chiba University
All About Solar Energy at SolarDaily.com
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