A practical charging strategy for an individual plug-in electric vehicle (PEV) is proposed. A cost function is constructed to reflect bidirectional electricity trade arising from surplus photovoltaic generation under the reward system called feed-in tariffs and time-of-use electricity pricing. It is then extended to include the revenue for providing vehicle-to-grid frequency regulation. In order to take advantages of high performance existing solvers, several mathematical techniques are applied to transform the discrete non-linear cost function to a differentiable continuous function. In the latter part of the paper, simulations are performed to verify and show the performance of the developed model. A quantitatively developed battery wear model is also applied during the simulations to calculate the effective operational cost, and to compare the costs for different control strategies. From the result of case study, the economic feasibility of the frequency regulation under the given circumstance is addressed as well.