Solar Energy Potentials In Laos

The main objective of this project is to investigate the solar energy potentials

of Lao People’s Democratic Republic (Lao PDR). To investigate the solar energy

potentials, solar radiation over Lao PDR was estimated using a satellite solar radiation

model. An 11-year period (1995-2005) of satellite image data from GMS5 and

GOES9 satellites were used as input of the model. This model accounted for the

reflectivity of cloud, absorption of water vapour, ozone and radiation depletion by

aerosol. The satellite data provided cloud information for the model. The absorption

of solar radiation due to water vapour was computed from precipitable water obtained

from ambient relative humidity and temperature at 17 meteorological stations. The

ozone data from the TOMS/EP satellite were used to compute the solar radiation

absorption by ozone. The depletion of radiation due to aerosols was estimated from

visibility data and the 5S radiative transfer model. Pyranometer stations were

established in 5 locations in Lao PDR: Vientiane, Luangprabang, Xamnua, Thakhak

and Pakxe. Global radiation measured at these stations was used to validate the

model. The validation was also performed by using existing solar radiation collected

at 3 stations in Thailand: Nongkhai, Nakhon Panom and Ubon Ratchathani. The solar

radiation calculated from the model was in good agreement with that obtained from

the measurements, with a root mean square difference (RMSD) of 7.2 %. After the

validation, the model was used to calculate the monthly average daily global solar

radiation for the entire country. The results were displayed as monthly radiation maps

and a yearly map. The monthly maps revealed the seasonal variation of solar radiation

affected by the monsoons and local geography and solar radiation is highest in April

for most parts of the country. From the yearly map, it was observed that the western

parts of the country received high solar radiation with the values of 17-18 MJ/m2-day.

The areas which receive the highest solar radiation are in the south with the values of

18-19 MJ/m2-day. The yearly average of solar radiation for the entire country was

found to be 15.8 MJ/m2-day. This solar radiation data revealed that Lao PDR has

relatively high solar energy potentials which can be utilized for various solar energy

applications. The maps can be used as a tool for site selection of solar energy

technologies. A solar radiation database was also developed for use in designing solar

energy systems.