Low-voltage photovoltaic (PV) expansion reduces energy revenue of utility grid but leaves reserve capacity and costs unchanged and hard to quantify. To address this issue, the utility grid promotes the green power direct supply scheme that deliver PV energy to consumers in behind-the-meter (BTM) community without relying on public transmission lines. With a clear ownership boundary, the utility grid can accurately measure and share the previously neglected cost of providing reserve capacity, thereby encouraging PV power generation to seek local reserve capacity in the BTM community to reduce cost. Dedicated slow-charging electric vehicle (EV) facilities in the BTM community, servicing EVs that have fixed arrival and departure schedules and long parking durations, can offer local reserve capacity to mitigate PV power deviations. This paper proposes an EV incentivization framework to provide local reserve capacity for PV power generation in the green power direct supply scheme. First, a stochastic optimization model is established to evaluate expected residual PV power deviation costs and determine the corresponding local reserve capacity demand. Second, a bi-level Stackelberg game model is formulated to describe the multi-round bargaining between the charging facility operator (CFO) and EV users. Simulation results demonstrate that the proposed EV incentivization framework effectively aggregates EV adjustable power, reduces PV power deviation penalties, and alleviates the reserve capacity burden of the utility grid.