Halide perovskites have emerged as a pivotal class of materials for solar energy conversion technologies, exhibiting outstanding optoelectronic properties, low-cost fabrication, and bandgap tunability. However, the predominance of lead-based compositions, in the most performing specimens, raises serious environmental and health concerns, threatening widespread deployment and long-term sustainability of the technology. As a response, the development of lead-free halide perovskites aims to retain the desirable characteristics of halide perovskites while reducing the toxicity associated with lead. This chapter exposes the motivation at the core of the volume; it introduces the scientific rationale, application domains, market opportunity, legislation challenges, and perspective of lead-free halide perovskite utilization in solar energy conversion. Emphasis is placed on the role of perovskite materials in photovoltaic and photocatalytic systems, where advances in composition design, stability enhancement, and interface engineering have enabled significant progress. Despite ongoing challenges, lead-free perovskites represent a promising pathway toward eco-friendly and efficient solar-converting technologies.