Solar radiation


For more information see in book: https://drive.google.com/file/d/0B8DPBxf33AI_d2pVY... (Thai language)

Solar radiation is an energy source of all solar energy devices and its characteristics in time and space is important for the development and application of solar energy technologies.

Prior to 1980's measurement of broadband solar radiation (0.3-3.0 micron) in Thailand were carried out only at a few locations which were insufficient for mapping the solar energy resource and applying new technologies. In response to this need, a solar radiation monitoring station was established at the Physics Department of Silpakorn University in 1981 by a researcher of SERL. The station was upgraded in 1986 with additional measurements of other components of solar radiation and a systematic data recording system.

Fig. 1 Solar radiation monitoring station set up at the Physics Department of Silpakorn University in 1981


Fig. 2 The renovated solar radiation at Silpakorn University


In collaboration with the Thai Meteorological Department (TMD) and support from National Research Council of Thailand (NRCT), three new stations were established at the regional centers of TMD in Chiang Mai (18.78 °N, 98.98 °E), Ubon Ratchathani (15.25 °N, 104.87 °E) and Songkhla (7.20 °N, 100.60 °E) in 1994.

Fig. 3 Solar station at Chiang Mai in 1994


Fig. 4 Solar station at Ubon Ratchathani in 1994


Fig. 5 Solar station at Songkhla in 1994


These stations were later upgraded with additional instruments to measure other components of solar radiation, Fig. 6.

Fig. 6 Solar stations in 2016


In 1995, SERL received computing hardware and software from the International Development Program (IDP) of the Australian Government in order to develop a technique for retrieving solar radiation from satellite data. IDP also sent Dr. Manuel Nunez from the University of Tasmania to help develop the technique at Silpakorn University.


Fig. 7 Computing devices supported by IDP


During 1997-1999, the Department of Energy Development and promotion (DEDP) (now called the Department of Alternative Energy Development and Efficiency, DEDE) collaborated with SERL in a project which developed solar radiation maps for Thailand. This work used data from GMS4 and GMS5 satellites in conjunction with solar radiation measurements at the four SERL stations.

Fig. 8 Solar radiation maps developed during 1997-1999.


With the collaboration of DEDE, similar work has been done for Laos, Cambodia and Myanmar during 2005-2009. Additionally, solar maps for Vietnam were created in 2013-2015 under the cooperation of the Institute of Geophysics, Vietnam Academic of Science and Technology and support from Office of Naval Research Global (NORG), USA.


a) Laos


b) Cambodia


c) Myanmar


d) Vietnam

Fig. 9 Solar radiation maps of a) Laos, b) Cambodia, c) Myanmar and d) Vietnam


In 2000-2002, SERL worked with DEDE to establish 25 solar radiation monitoring stations over Thailand, with the number later extended to 38 stations.

Apart from broadband solar radiation, SERL also has worked in applications involving other regions of the solar spectrum, mainly the solar ultraviolet, daylight, photosynthetically active radiation (PAR), solar and thermal infrared radiation and the solar spectrum.

For more information see in book: https://drive.google.com/file/d/0B8DPBxf33AI_d2pVY... (Thai language)


Publication in Solar Radiation

  1. Janjai, S., Jantarach, T., Laksanaboonsong, J. A model for calculating global illuminance from satellite data, Renewable Energy 28, 2355-2365, 2003
  2. Janjai, S., Laksanaboonsong, J., Nunez M., Thongsathiya, A. Development of a method for generating operational solar radiation maps from satellite data for a tropical environment, Solar Energy 78, 739-751, 2005
  3. Kift, R., Webb, AR., Page, J., Rimmer J., Janjai, S. A web-based tool for UV irradiance data: predictions for European and South-East Asian sites, Photochemistry and Photobiology 82(2), 579-586, 2006
  4. Janjai, S., Tohsing, K., Nunez, M., Laksanaboonsong, J. A technique for mapping global illuminance from satellite data, Solar Energy 82, 543-555, 2008
  5. Janjai, S., Masiri, I., Nunez, M., Laksanaboonsong, J. Modeling sky luminance using satellite data to classify sky conditions, Building and Environment 43, 2059-2073, 2008
  6. Janjai, S., Deeyai, P. Comparison of methods for generating typical meteorological year using meteorological data from a tropical environment, Applied Energy 86, 528-537, 2009
  7. Janjai, S., Pankaew, P., Laksanaboonsong,J. A model for calculating hourly global solar radiation from satellite data in the tropics, Applied Energy 86, 1450-1457, 2009
  8. Janjai, S., Buntung, S., Wattan, R., Masiri, I. Mapping solar ultraviolet radiation from satellite data in a tropical environment, Remote Sensing of Environment 114, 682-691, 2010
  9. Janjai, S., Kirdsiri, K., Masiri, I., Nunez, M. An investigation of solar erythemal ultraviolet radiation in the tropics: a case study at four stations in Thailand, International Journal of Climatology 30, 1893-1930, 2010
  10. Janjai, S. A method for estimating direct normal solar irradiation from satellite data for a tropical environment, Solar Energy 84, 1685–1695, 2010
  11. Janjai, S., Plaon, P. Estimation of sky luminance in the tropics using artificial neural networks: Modeling and performance comparison with the CIE model, Applied Energy 88, 840–847, 2011
  12. Janjai, S., Pankaew, P., Laksanaboonsong, J., Kitichantaropas, P. Estimation of solar radiation over Cambodia from long-term satellite data, Renewable Energy 36, 1214-1220, 2011.
  13. S. Janjai, R. Wattan, Development of a model for the estimation of photosynthetically active radiation from geostationary satellite data in a tropical environment, Remote Sensing of Environment 115, 1680–1693, 2011
  14. Janjai, S., Sricharoen, K., Pattarapanitchai, S. Semi-empirical models for the estimation of clear sky solar global and direct normal irradiances in the tropics, Applied Energy 88, 4749–4755, 2011
  15. Janjai, S., Pattarapanitchai, S., Laksanaboonsong, J. An Improved Model for the Estimation of Solar Radiation from Satellite Data for Thailand, Journal of the Institute of Engineering 8 (3), 130–139, 2012
  16. Nimnuan, P., Janjai, S. An approach for estimating average daily global solar radiation from cloud cover in Thailand, Procedia Engineering 32, 399-406, 2012
  17. Prathumsit, J., Janjai, S. Correlation models for the estimation of diffuse fraction of global illuminance from satellite data, Procedia Engineering 32, 414-420, 2012
  18. Pattarapanitchai, S., Janjai S. A semi-empirical model for estimating diffuse solar irradiance under a clear sky condition for a tropical environment, Procedia Engineering 32, 421-426, 2012
  19. Buntoung, S., Choosri, P., Dechley, A., Masiri, I., Wattan, R., Janjai, S. An investigation of total solar ultraviolet radiation at Nakhon Pathom, Thailand, Procedia Engineering 32, 427-432, 2012
  20. Janjai, S., Diffuse - global correlation models at four locations in Thailand, International Journal of Renewable Energy 7, 11-21, 2012.
  21. Janjai, S., Masiri, I., Laksanaboonsong, J., Satellite-derived solar resource maps for Myanmar, Renewable Energy 53, 132-140, 2013
  22. Janjai, S., Masiri, I., Pattarapanichchai, S., Laksanaboonsong, J., Mapping global solar radiation from long-term satellite data in the tropics using an improved model, International Journal of Photoenergy 2013, ID 210159, 1-11, 2013
  23. Janjai, S., A satellite-based sky luminance model for the tropics, International Journal of Photoenergy 2013, ID 260319, 1-11, 2013
  24. Janjai, S., Nunez, M., Prathumsit, J., Wattan, R., Sabooding, R., A semi-empirical approach for the estimation of global, direct and diffuse illuminance under clear sky condition in the tropics, Energy and Buildings 66, 177–182, 2013.
  25. Janjai, S., Sripradit, A., Buntoung, S., Pattarapanitchai, S., Masiri, I., A simple semi-empirical model for the estimation of photosynthetically active radiation from satellite data in the tropics. International Journal of Photoenergy 2013, ID 857072, 1-6, 2013
  26. Janjai, S., Prathumsit, J., Buntoung, S., Wattan, R., Pattarapanitchai, S., Masiri, I., Modeling the luminous efficacy of direct and diffuse solar radiation using information on cloud, aerosol and water vapor in the tropics. Renewable Energy 66,111-117, 2014
  27. Janjai, S., Pattarapanitchai, S., Prathumsit, J., Buntoung, S., Wattan, R., Masiri, I., A method for mapping monthly average hourly diffuse illuminance from satellite data in Thailand. Solar Energy 102, 162–172, 2014
  28. Janjai, S., Wisitsirikun, S., Buntoung, S., Pattarapanitchai, S., Wattan, R., Masiri, I., Bhattarai, B.K.,Comparison of UV index from Ozone Monitoring Instrument (OMI) with multi-channel radiometers at four sites in the tropics: effects of aerosols and clouds. International Journal of Climatology 34, 453–461, 2014
  29. Buntoung, S., Janjai, S., Nunez, M., Choosri, P., Pratummasoot, N., Chiwpreecha, K., Sensitivity of erythemal UV/global irradiance ratios to atmospheric parameters: application for estimating erythemal radiation at four sites in Thailand. Atmospheric Research 149, 24–34, 2014
  30. Pattarapanitchai, S., Janjai, S., Tohsing, K., Prathumsit, J. A technique to map monthly average global illuminance from satellite data in the tropics using a simple semi-empirical model. Renewable Energy 74, 170-175, 2015
  31. Janjai, S., Wattan, R., Sripradit, A., Modeling the ratio of photosynthetically active radiation to broadband global solar radiation using ground and satellite-based data in the tropics. Advances in Space Research 56, 2356–2364, 2015
  32. Wattan, R., Janjai, S., An investigation of the performance of 14 models for estimating hourly diffuse irradiation on inclined surfaces at tropical sites. Renewable Energy 93 667-674, 2016