<p>This review critically examines recent advances in improving the ability of flat plate solar collectors (FPSCs), particularly focusing on passive, active, and hybrid strategies. Passive methods remain widely deployed in solar-rich regions due to their design simplicity and cost-effectiveness, while hybrid approaches that combine both active and passive techniques are emerging as promising solutions to achieve higher thermal efficiency and shorter payback periods despite increased upfront costs. Key innovations include optimisation of fluid flow pathways, incorporation of nanoparticles to boost thermal conductivity, and absorber plate modifications such as wavy geometries, which enhance thermal efficiency by up to 30% and exergy by 20% compared to conventional FPSCs. The development of spectrally selective multilayer cermet coatings demonstrates exceptional thermal stability at ultra-high temperatures (up to 650&#xa0;°C), expanding the applicability of FPSCs in concentrating solar power systems. Furthermore, the integration of swirl generators and helical inserts has been shown to reduce irreversibility while improving thermo-hydraulic performance. Despite their delivery of predominantly low-grade heat, FPSCs remain one of the most sustainable and economically viable solar energy technologies, exhibiting lower embodied energy and CO₂ emissions than PV and PV/T systems. This review not only consolidates technological innovations but also highlights persisting challenges and scientific gaps, offering pathways for future research to accelerate the deployment of FPSCs in addressing global energy needs and climate change mitigation.</p>