Driven by the global pursuit of carbon neutrality, green hydrogen produced from renewable energy has emerged as a promising pathway for decarbonization. Among the various application scenarios, DC off-grid photovoltaic (PV)-proton exchange membrane (PEM) hydrogen production is a representative solution. However, PV generation typically exhibits low utilization efficiency, and the volatility of photovoltaic output poses a serious challenge to the efficient and stable operation of DC off-grid hydrogen production systems and the lifespan of equipment. To improve system efficiency and economic performance, this study quantitatively evaluates lifetime degradation in a proton exchange membrane electrolyzer (PEMEL) and lithium-ion batteries (LIBs) based on their operating mechanisms. Building on this evaluation, an optimization model that minimizes the levelized cost of hydrogen is built, and PEMEL gas safety, start-up/shutdown and overload operation, equipment safety and capacity limitations, as well as system power balance are taken into account as constraints. Accordingly, a coordinated operation optimization strategy for DC off-grid PV-PEM hydrogen production considering efficiency and lifetime degradation is proposed. Finally, using typical regional solar irradiance and ambient temperature data, the optimal operating performance under different external conditions is obtained and benchmarked against representative existing schemes, demonstrating the feasibility and advantages of the proposed method.