With silicon heterojunction (SHJ) solar cells at their practical efficiency limit, their long-term reliability and stability remains the hindering block toward mass adoption. Precisely, it is the degradation of passivation over time under field operating conditions at amorphous silicon (a-Si:H) and crystalline silicon (c-Si) interface that is a concern. Therefore, we investigate the passivation quality of a-Si:H/c-Si in terms of interface defect and charge density by extracting surface recombination velocity (SRV) using the temperature- and injection- dependent lifetime spectroscopy technique. Our results show passivation quality of the interface degrades at elevated temperature due to thermally activated defects at the surface. Moreover, temporal dependence of a-Si:H/c-Si interface passivation shows degradation due to increase in SRV originating from failing chemical passivation exhibited by an increase in defect density at the interface. Interestingly, field passivation seems to remain the same through the time of these experiments.