On-line energy analysis in PV buildings connected to the utility grid

This paper presents a new software tool to estimate the energy flows in grid-connected photovoltaic (PV) buildings. The main aim of this simulator is to predict the energy balance and economic behaviour of PV buildings connected to the utility grid so that different alternatives can be tested to optimise designs. Consumption analysis is performed by considering six parameters that determine the building´s response, following a methodology based on data from monitored buildings, an internal reference building and regression analysis. Photovoltaic energy estimates are obtained by calculating solar radiation hourly values and simulating individual PV cells. The resulting energy balance and the economic behaviour of the building are then estimated and the results given in tables, diagrams and several graphic formats. As an example, a university office building located in Madrid (Spain) is presented and the conclusions reached during several simulation runs are discussed. To make the tool widely available to any potential users it has been programmed in a Java applet format and deployed on a World Wide Web server. By simply using an up-to-date WWW browser, the simulator can be concurrently run by multiple users on the Internet.