In this thesis we developed a multipurpose modular system for solar cells and smaller photovoltaic modules illumination. For the purpose of LED array design, we developed a numerical simulator. Using numerical optimization algorithms, we can calculate the optimal number, location and power of individual LEDs in an array on a predefined area using illumination intensity and homogeneity criteria. Results of calculation were used in design of a layout for an array of LEDs that allows us to reach the illumination power density of 500 Wm2 with maximal non-homogeneity of 2 %. For the implementation of the LED light source we developed a power supply module capable of powering various typical LEDs in a voltage range of 3 V–42 V and a current range of 0,1 A–1 A. This module can also modulate the brightness of these LEDs with 5 % accuracy. LED light modules are also capable of measuring the current and temperature of the LEDs and communicating with each other and with the control unit. We tried multiple LEDs on the light module and measured some key characteristics. To control the light modules, we developed a control unit based on an ARM microcontroller. This control unit communicates with the light modules and a personal computer. It allows control of the light intensity of the light modules and monitors their temperature and output current. We have also developed the complete control module firmware. Finally, we merged the light modules and the control unit into a functional light source for artificial ageing of PV modules and solar cells under UV illumination.