Uthman Abdullatif Fattah2022-05-182022-05-185443https://drepo.sdl.edu.sa/handle/20.500.14154/3040First a survey of principles used in designing the principal types of solar radiation-measuring instruments is described together with a brief description of the various factors affecting their calibration and limiting their lifetimes. Then a theoretical analysis of thermal effect in transistors is developed, with the aim of designing an electronic apparatus for measuring total and possibly direct solar radiation. Finally, a laboratory set-up of such “transheliometer” is reported along with the pertinent calculations and experimental observations. The major objective in this work is to assess the suitability of the bipolar junction transistor (BJT) as a radiation sensing device in order to meet the requirement of designing a simple, effective and economic radiation-measuring instrument.enThesis