The Phase I was successful in delivering a complete prototype of the proposed innovation, an LED-based, solid state, large area, pulsed, solar simulator (ssLAPSS). The prototype not only proved the initial concept but significantly reduced risk and dramatically increases our ability to deliver a fully functional ssLAPSS in Phase II. 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 solar panel string under test. The ssLAPSS is adjustable in spectrum for selected wavelengths and Class A, the highest standard, for spatial uniformity and temporal stability. The ssLAPSS consists of LED modules that are repositioned in a mounting frame to test many strings on a panel in sequence. The ssLAPSS also includes optical sensors so that all metrics can be calibrated and validated automatically. Solar simulation is critical for all solar cell testing, and current large area, pulsed solar 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 prime contractors, solar panel integrators and solar cell manufacturers have a critical need for this capability, which presents excellent commercialization opportunities after the Phase II maturation of the technology.