A system, method and computer program product to assist in managing the physical plant mechanisms and market finances for a deregulated electricity grid or regulated utility grid, populated with solar electric generation capacity. This system provides tools to assist grid operators in the scheduling and dispatch of generation resources in an electrical grid populated with solar electric generation capacity, a week in advance, on an hourly basis. It also provides tools to assist companies engaged in generation, distribution and energy marketing, in the electrical power industry, to manage their contractual supply obligations in the day-ahead hourly wholesale market and the spot market, in an electrical grid populated with solar electric generation capacity. This process can also be used to predict solar loading of building structures, using forecast irradiance data as inputs to common building energy modeling programs, a week in advance, on an hourly basis.