The boron-oxygen related defect is a well-known lifetime killer and in consequence seemed to be a show-stopper for the high efficiency solar cell development on boron-doped substrates. However, the related degradation may be overcome by the regeneration process eliminating the harmful defects. The recently finished research project BORNEO aimed at a more fundamental understanding of boron-oxygen related regeneration in order to answer the pending questions that impede industrial application so far. Some basic relations between macroscopic parameters (such as the manufacturing process of the solar cell and the regeneration conditions) and microscopic processes (such as the defect kinetics) are explained, and which lessons were learned to be able to realize a fast and reliable regeneration process not only on lifetime samples, but also on solar cell level, and why the chosen cell architecture matters.