The restricted energy budget of energy-harvesting sensor nodes demands algorithms for adaptive duty-cycling. However, their comparison and development is hindered by the lack of reproducibility of environmental conditions. We enable replaying recorded light conditions by building an affordable light box. Our self-developed control circuit and high power LEDs allow us to repeatedly replay real environmental illumination data through current and voltage traces. This allows us to directly compare the behavior of nodes running different energy-aware and -predictive algorithms.