In this paper we present the results of different contract types and specifications for vehicle-to-grid supply. We developed a classification of contract types and specifications for vehicle-to-grid supply based on demand response literature. Such contracts provide rules and agreements between electric vehicle drivers and aggregators regarding the operation of the car for supplying power when parked. Applying the contract concepts to a microgrid with fuel cell electric vehicles that supply power, we compare the static volume-based contract to the control-based approach which was assumed in previous work. Using agent-based modeling and simulation we explore the effect of these two contract types on the requirements for drivers and the system performance of the microgrid. The results show that with volume-based contracts, the plug-in hour requirements and supplied V2G per car are lower on average, and that 91% of the residual load can be supplied with vehicles.