The ssLAPSS expands on the SOP LAPSS by upgrading the light sources to enable future solar cell technologies while maintaining all of the current, proven calibration and test methods. The ssLAPSS enables testing of current SOP 3-junction cells and also upcoming 4- and 6-junction solar cells. The ssLAPSS uses planar arrays of 6 different wavelength LEDs located in close proximity to the string under test in the solar array. The individual LED intensity control gives great flexibility to meet power and spatial uniformity requirements. The LED sources are selected to each illuminate one junction in a 6-junction cell. The same LEDs will also be used for 3- and 4-junction cells. This means that one ssLAPSS can measure the current (3-junction) and future (4- and 6-junction) cells. This technology is also highly flexible so that cells with an even greater number of junctions or cells with different spectral divisions could be measure by producing a ssLAPSS with a greater number of LEDs or a different spectral mix of LEDs in the illumination array. In addition to providing 3-, 4- and 6-junction cell capability at lower systems costs than the SOP LAPSS, the ssLAPSS also has many other benefits: it requires minimal clean room floor space, it can provide low light levels (LILT), it can measure arrays in horitozontal orientations, it can scale to any bus voltage or string length, it uses proven standards and test methods and it provides for easier calibration than the SOP LAPSS. Four- and 6- junction LAPSS technology is necessary to evaluate, test and fly advanced solar cell technologies. The ssLAPSS extends an essential, proven measurement method to the future of space power conversion technologies.