This report discusses two projects: developing an Illumination Testing Facility for precise solar simulation and; implementing quality checks on a 4Pi Sun Sensor assembly, including creating an Illumination Test Set-Up. The significance of solar simulators is highlighted, as they are crucial for testing and studying the performance of photovoltaic devices being illuminated by sunlight under various environmental conditions. Different types of solar simulators, such as continuous and pulsed, are explained, along with their uses in calibration, efficiency measurement, material testing, component testing, and research of various devices. The 4Pi Sun Sensor’s role in Attitude Determination is described, emphasising the need for accurate and reliable testing. The methodology employed in both projects is presented. The regular maintenance of the Newport 94043A Solar Simulator and the assembly and testing procedures for the 4Pi Sun Sensor are described in detail. The various tests conducted on the sun sensor, such as visual inspection, electrical tests, illumination tests, and operation of the instruments involved, like the Keithley 2401 Sourcemeter and the Murata SCL3300-D01-PCB tilt sensor, are explained. The results section includes the findings from the solar simulator testing, highlighting the need for replacing the Xe-Arc Lamp and the results from the sun sensor’s illumination tests on different axes. The conclusion emphasises the importance of these projects in understanding solar simulation and sun sensor technology, providing hands-on experience in testing and calibration procedures for photovoltaic devices and spacecraft orientation systems. Overall, these projects contribute to advancement in solar energy and aerospace technology by ensuring accurate testing and calibration of devices used in these fields.