The remarkable growth of photovoltaic energy sources in power generation is boosted by grid-connected inverters, with transformerless (TL) alternates gaining prominence due to their higher efficiency, cost-effectiveness, and compact size. However, the challenge of converter designs in these inverters necessitates continuous research for innovative topologies. This chapter presents a detailed exploration of the evolution of TL inverter designs, emphasizing enhanced efficiency, boosting capability, and reduced leakage current. Categorized by structure and subcategorized by control techniques, the inverters’ components and connections are differentiated for clarity. Performance evaluation based on performance and construction strengths and weaknesses is provided, offering valuable insights for researchers and engineers. Shifting the focus to renewable energy, particularly solar power, the critical review extends to TL grid-integrated solar inverters. Examining primary operations, research advancements, performance parameters, challenges, and industrial solutions, simultaneously, the discussion expands to the challenges associated with safety hazards in TL-based PV inverters, highlighting the importance of complying with stringent safety standards and providing a review and classification of various TL inverters, ensuring clarity on the development of next-generation grid-connected PV systems.