Long-term responses of photosynthetic apparatus to altered irradiances of PAR, termed acclimation, involve selective synthesis and/or degradation of chloroplast components to adjust the composition and function of the photosynthetic apparatus. In this work we investigate especially acclimation changes induced by increased PAR (HI) concerning the nature of regulation of excitation energy transfer (EET) efficiency from light harvesting complex (LHCII) to the core of photosystem II (PSII). The acclimation of WT plants to HI results in reduced efficiency of EET from Chl b and carotenoids within PS II in vivo, whereas the EET from Chl b and carotenoids within individual isolated PS II PPC remains unaffected in HI acclimated plants. Thus, our results indicate that HI acclimation changes of EET efficiency from LHCII to RC of PSII in vivo are caused rather by altered macro-organization of PSII supercomplexes then by inner reorganisation of LHC II monomers and trimers.