For PEC, significant progress with respect to STH efficiency (> 26%) and PEC cell stability is required, as lifetimes of at least 2 years are needed to alleviate the high costs resulting from cell replacements. Furthermore, solar concentration is a crucial component to enable low-cost hydrogen production using PEC and cells should be optimized to operate with high solar concentration factors (> 50), necessitating highly absorbent semiconductors and highly active electrocatalysts.