The critical limitations of solar energy, which are temporal and geographic mismatches with consumption as well as utilization for material manufacturing, can be addressed with solar fuels. However, no direct solar-to-chemical conversion processes have reached commercial scale. Direct, efficient, integrated solar-to-chemical energy conversion via photoelectrochemical cells (PECs) is a promising route to low-cost, scaled solar fuel manufacture. Historical limitations in conversion efficiency and material cost have hindered the deployment of PECs. The recent and rapid advances in halide perovskite solar cells, achieving >26% power conversion efficiency with low material costs and facile processing, have opened new avenues for PECs. In the first chapter, we overcome the key hurdle to perovskite-based PECs through the design of a conductive adhesive-barrier which can simultaneously protect the sensitive optoelectronic components without adding series resistance, achieving 13.4% solar to hydrogen (STH) efficiency with single-junction perovskite solar cells and 20.8% STH with silicon-perovskite tandems. In the second thrust, we conduct a robust technoeconomic analysis to identify further hurdles to commercialization and suggest target metrics and figures of merit for future research to achieve commercially competitive green hydrogen at <$2/kg. In the third and final thrust, we demonstrate a design protocol that reduces the key contributor to panel cost, catalyst material price, by an order of magnitude while preserving or increasing STH and lifetime. This constellation of work will be the bedrock for the commercial proofing of PEC water-splitting, and a platform for other reactions.