Abstract Interest in perovskite solar cells (PSCs) has grown, with advances in stability and scalability for commercialization. However, in real-world conditions, PSCs can encounter potential-induced degradation (PID), primarily due to sodium ion (Na+) migration from conventional soda-lime glass (SLG) substrates. This study investigates whether PID can be completely avoided using Na+-free substrates such as polyethylene terephthalate (PET). PET and SLG-based PSCs were subjected to –1000 V PID stress. The test was conducted in an inert environment to exclude other degradation factors. After 300 h, PET-based PSCs demonstrated only a 0.11% efficiency loss, staying well below the 5% stability threshold, compared to a 15% loss in SLG-based PSCs. The results confirm that using Na+-free substrates effectively prevents PID, and that Na+ migration is the primary cause of degradation during PID stress. These findings support further research to develop PID-resistant PSCs. Impact statement Potential-induced degradation (PID) is a critical challenge for perovskite solar cells (PSCs) in real-world conditions, significantly impacting their stability and posing a barrier to large-scale commercialization. This study provides evidence that PSCs can be engineered to resist PID. The findings pave the way for developing strategies to mitigate, prevent, and even eliminate PID in future PSC designs. Moreover, the study confirms that Na+ migration is the primary driver of degradation during PID stress under inert conditions, providing valuable insights that could accelerate the advancement of long-term stability solutions for PSCs, thereby expediting their commercialization. Graphical abstract