Bringing solar site analysis to smartphones

Performing a site analysis is an important first step in planning a solar installation. This paper details progress made in development and validation of an Android smartphone-based application to assist in the site analysis process. The methodology used is based on techniques from literature and standard practice. Hourly typical meteorological year (TMY3) solar resource data is used to estimate the energy available to a potential solar collector. These estimates are extended to represent plane-of-array irradiation using a standard diffuse-sky model. The user is prompted to trace the horizon using the phone's camera in order to determine the presence of objects that may introduce shading. This shading data can be used to calculate the impact on the estimated resource, or can be used to generate solar access inputs to other standard software. Techniques found in literature were used to compute optimum collector orientations based on the shaded solar access. The calculations within the app were compared with those made using the NREL System Advisor Model software. Data from the app canbe stored for subsequent transfer to a computer for further processing or integration with other software tools. Some limitations associated with using the smartphone platform for this purpose will be discussed. The chief advantages offered by this software are its ability to make use of existing smartphone hardware and documentation of the methodology in non-proprietary venues.