  Sharing economy has disrupted many industries. We foresee that electricity
storage systems could be the enabler for sharing economy in electricity sector,
though its implementation is a delicate task. Unlike in the 2-tier Time-of-Use
(ToU) pricing, where greedy arbitrage policy can achieve the maximal
electricity bill savings, most existing ToU schemes consist of multiple tiers,
which renders the arbitrage challenging. The difficulty comes from the hedging
against multiple tiers and the coupling between the decisions across the day.
In this work, we focus on designing the energy sharing mechanism for single
peaked ToU scheme. To solve the problem, we identify that it suffices to
understand the arbitrage policies for two forms of 3-tier ToU schemes. We
submit that under mild conditions, the sharing mechanism yields a unique
equilibrium, which supports the maximal social welfare.
