Reliable solar PV power plants will deliver the expected performance throughout their entire service life. They will experience very limited component degradation, failures or system down-time. Improving reliability means derisking electricity production and return on investment of PV systems. Mitigation of risks supports the bankability of PV systems and serves as an enabler for accelerated deployment of solar PV technologies. Ongoing basic research remains necessary for the photovoltaic industry to continue advancing its knowledge and improving lifetime system performance. This document addresses the foundations and reasons why reliability research is crucial to the solar PV industry’s continued growth.