<p>The large-scale installation of solar photovoltaic (PV) systems has driven the emergence of low-carbon power supply systems, with solar PV becoming a key transformative technology. However, the role of PV in contemporary grids now extends beyond the challenges of intermittency and inverter harmonization. The proliferation of PV in transmission and distribution networks makes PV integration a multidisciplinary and multi-regulatory challenge. This review focuses on the structures and systems required for safe PV integration, addressing challenges related to protection, safety, emerging communication and cybersecurity risks, and barriers to market incorporation. It presents and analyzes issues related to voltage variation, frequency stabilization, reactive power support, harmonic distortion, fault ride-through capability, and active power curtailment. Protection methods are structured according to their capabilities, limitations, and maturity. The review also focuses on cybersecurity challenges within the context of PV integration from an overall architectural perspective. Rather than focusing only on individual threats, it emphasizes integration frameworks, challenges, and system-level considerations. The study also examines market integration through comparative regulatory pathways, pricing frameworks, and aggregation roles. Ultimately, the study advocates unified frameworks and protective co-design as crucial elements for cybersecurity, market-capable integration, resilience-oriented coordination, and future protection research. The security objectives of resilient systems indicate that PV integration should be treated as a combined protection, cybersecurity, and market challenge.</p>