A system and method for remotely inputting power plant data into a database and for calculating reserve times for which power plants can supply power to consumer equipment. The system includes a data input module for receiving power data from a remote user and for inputting power plant data into a database. In a preferred embodiment, the system is an integral part of a comprehensive site planning facility and interfaces with a permanent site facility database and a temporary relational database. Both databases store data relating to sites, power plants associated with sites and component data related to power plants. The data input module permits users to add, modify and remove power plant data associated with sites which are stored in the temporary relational database. The data input module also permits users to edit consumer equipment load values associated with power plants, regardless of whether data for associated sites are maintained in the site facility planning database or the temporary relational database. A calculation module retrieves data from the database and calculates reserve times for which power plants can supply power to consumer equipment. As a precautionary measure, the calculation module preferably employs correction factors which exaggerate consumer equipment loads and underestimate power plant reserve time. Users interface with the system via a web browser interface thus permitting users to access the system from any computer running a browser and connected to a company-wide intranet or the like. In an alternative embodiment, the system implemented is a stand-alone system in which only the temporary relational database is employed.