  Peer-to-Peer (P2P) energy trading provides various benefits over conventional
wholesale energy markets and makes renewable energy more accessible. This paper
proposes a novel multi-layer P2P energy trading system for microgrids based on
IOTA 2.0, which is a distributed ledger technology (DLT) primarily designed for
Internet-of-Things (IoT) applications. The proposed energy trading system,
which is a manifestation of a cyber-physical system (CPS), exploits the
benefits brought by IOTA's unique ledger structure as well as the recently
introduced IOTA smart contract protocol (ISCP). Further, it implements a
uniform double-auction market mechanism and a hierarchical routing structure
for interconnected microgrids. Performance evaluation demonstrates key benefits
over wholesale markets as well as speed, energy efficiency and cost benefits
over conventional blockchain-based P2P energy trading systems.
