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.