A modular outdoor large item vending system for large items such as propane tanks, liquid petroleum gas cylinders of various sizes and other items that must be stored in and dispensed from a hazardous location compliant system. The vending system can be placed on a store front, parking lot, campsite, or park, and comprises a master module assembly connected to a plurality of add-on module assemblies with each of the master module assembly and the add-on module assemblies having compartments to hold large items which are dispensed from the compartments when a payment is made through a credit card reader interface located on a master module control compartment door face. The large item vending system of the invention is powered by AC current which is turned to DC power by a power supply, or DC batteries charged by AC power and/or solar power, or by other power means.