Role of Artificial Intelligence in P2P Energy Trading for Transforming Smart Homes to Smart Cities: A Comprehensive Survey

Smart infrastructures, electric cars, and DERs have hastened the transition from centralized power systems to decentralized, prosumer-driven energy ecosystems. P2P energy trading allows families, villages, and cities to trade energy directly without a third party, making it important to this shift. These markets demand decision-making skills beyond standard control approaches because to their complexity, stochasticity, and real-time monitoring. AI is becoming the key driver of P2P trading, offering prosumers and municipalities with intelligent forecasting, optimization, automation, and security solutions. This survey provides a comprehensive overview of the role of AI in P2P energy trading, outlining its applications in smart homes and smart cities. We survey over a decade of research and present a taxonomy of more than 40 AI techniques, including machine learning, deep learning, reinforcement learning, optimization heuristics, federated and transfer learning, hybrid AI-blockchain models, and edge-cloud intelligence. We analyze the capability, application domains, challenges, and case studies of each technique. The poll also consolidates key open issues including privacy, interoperability, explainability, real-time latency, and the lack of standardized AI benchmarking platforms. Based on these insights, we propose future directions such as federated multi-agent frameworks, behavioral modeling, massive language model integration, quantum AI, standardized digital twin platforms, AI-driven policy simulations, and debiasing of ethical bias. This work reveals how AI can transform smart homes into active prosumers and their interactions into city-scale decentralized energy ecosystems by rigorously connecting technological advancements to real-world challenges.Keyword: Artificial intelligence, P2P energy trading, smart homes, smart cities, distributed energy resource, intelligent energy management systems, energy market design, sustainable energy transition.