In research laboratories, new photovoltaic materials are monitored over long periods of time under constant light illumination to test their stability. However, in the real-world, constant illumination does not occur as the earth rotates around the sun giving diurnal light cycles. Whist outdoor testing gives the most true-to-life simulation, there are confounding factors such as air temperature and humidity which are known to affect solar cell performance. One solution is to simulate the sun’s cycling light intensity in a controlled laboratory environment where other variables such as temperature, humidity and atmospheric composition can be controlled. This project will involve modifying an existing LED solar simulator to provide a cycle that mimics that of the sun over 24- hour periods. By adjusting the current supplied to the LEDs, their intensity can be controlled programmatically using either a computer or microcontroller. To best represent the light in Saudi Arabia, outdoor measurements of light intensity will be taken and reproduced in the solar simulator.