Previous work has shown that it could be profitableon some control markets to use Plug-in Hybrid ElectricVehicles (PHEV) as control power resources. This concept,where battery driven vehicles such as PHEVs provide ancillaryservice to the grid is commonly referred to as Vehicleto Grid (V2G). The idea is to sell the capacity and energy ofthe parked PHEVs on the control market. Due to the factthat cars on average are parked 92% of the day, the availabilityof this capacity could be very high, even though it willbe highly dependent on commuting patterns in peak hours.Further, as each PHEV has a very small capacity from a gridperspective, it is necessary to implement an aggregating controlsystem, managing a large number of vehicles. This paperpresents a Monte Carlo simulation model where technical issuessuch as the reliability in communication for a large fleetof PHEVs is included. The communication in the simulationmodel is based on data from Automated Meter Reading(AMR) systems, which share important charachteristics withV2G communications. Moreover, the simulation is based onavailable data on the distributions of commuting departuretimes and travel distances, as well as average driving powerconsumption, PHEV battery capacities and the market constraintsof the secondary control market in Germany.