Design and construction of a novel large area LED solar simulator for photovoltaic cell characterization

Solar simulators are a precision research grade instruments especially designed to test and evaluate the efficiency of new materials and structures within photovoltaic devices in a laboratory setting. Rapid advances in high power light emitting diodes (LEDs) have provided the opportunity to design and construct solar simulators from arrays of discrete LED light sources to imitate the spectral distribution of sunlight as it varies diurnally and mimic the standard defined spectrum of the sun. LEDs offer numerous advantages over lamp-based solar simulator technology currently used, in terms of their spectra, lifetime and electrical efficiency. This thesis describes a novel, ten-colour, LED-based, solar simulator design, incorporating tessellated hexagonal array geometry, to allow the assembly of large area solar simulator units (LASS) providing highly- efficient, uniform illumination over large areas. Three prototypes of LED-based solar simulators have been designed, optically-modelled, constructed, and evaluated. The ten-colour design was tested for suitability as a solar simulator under three criteria: spectral match, spatial non-uniformity and temporal stability, and a comparison with the classical xenon lamp based solar simulator has been performed by measuring the current-voltage response and spectral response of a variety of solar cells. The results demonstrate the new LED-based solar simulator design meets a Class AAA classification according to the three official bodies regulating solar simulator standards, the International Electrotechnical Commission; the American Society for Testing and Materials and; the Japanese Industrial Standard, over the large illumination area. This work has provided new opportunities for low-cost, large-area, variable-spectrum solar simulation studies of photovoltaic systems and materials.