The central administrative board on hydrometeorology of the Ministry of Emergencies of the Kyrgyz Republic is entitled to measure meteorological and hydrological data in the Kyrgyz Republic. There are in total 31 weather stations and 75 hydrological stations. One of the weather stations “Frunze” is situated in the west part of Bishkek. The measurement equipment is remained from the USSR period. An actual value of global and diffuse solar radiation is measured 5 times a day at 6.30, 9.30, 12.30, 15.30 and 18.30. Till 1993 daily solar irradiation on horizontal surface was measured by an integrator. This device is, however, absent since 1993 for technical reasons. Therefore, since 1993 daily solar irradiation is estimated by linear interpolation of solar radiation between 5 measured points taking into account the time of sunrise and sunset (the so-called trapezium method). The central administrative board on hydrometeorology claims the accuracy of this method to be in the range of 10% for monthly sums of solar radiation.