In micro concentrating photovoltaics (CPV) minimized components are used and promise significant cost reduction due to massive manufacturing parallelization. At Fraunhofer ISE, we have developed a micro-CPV module based on a circuit board on glass, 5-junction micro concentrator solar cells, spherical ball lenses and a silicone-on-glass primary lens optics. Various prototypes from single cell-lens units to panel-sized 24“×18” modules were fabricated and tested. Due to the small size of the components, process tolerances are of special relevance and can significantly affect module performance. We present a novel modeling approach to study this influence quantitatively based on a nested Monte Carlo optical and electrical simulation. Furthermore, we present experimental results of prototype modules measured outdoors. For a 60-cell submodule-class prototype a power rating according to IEC 62670–3 was performed and CSTC and CSOC efficiencies of 36.5% and 33.0% are demonstrated.