As a result of significant technical effort, the Phase I was successful in delivering a solar simulator prototype that not only proved the initial concept but will significantly reduce future risk and increase our ability to deliver a fully-functional solar simulator in Phase II. The proposed innovation is an LED-based, laboratory-scale, solar simulator. The proposed innovation simulates AM0 response of single, dual, 3, 4, 5 and 6 junction solar cells by using an array of different wavelength LEDs in close proximity to the cell under test. The simulator is adjustable in spectral matching for selected wavelengths and Class A, the highest standard, for spatial uniformity and temporal stability. The solar simulator illuminates a square area 10 inches by 10 inches and includes optical sensors so that all metrics can be calibrated and validated automatically as needed. Solar simulation is critical for all solar cell testing, and current simulators will not work for coming 4, 5 and 6 junction technologies. Because the vast majority of NASA missions rely on solar cells, this is critical, enabling test technology for future solar cells. While accurate solar simulation is critical to all solar cell missions, it is particularly important to missions requiring large amounts of power, such as solar electric propulsion (SEP) missions. Beyond NASA's needs, other members of the aerospace community, including solar cell manufacturers, test labs and research institutions, have a critical need for this capability which presents excellent commercialization opportunities after the Phase II maturation of the technology.