Solar Survey: Development and validation of a smartphone-based solar site assessment tool

Solar site surveys are an important step in assessing the suitability of a site for a proposed solar power installation. This paper details investigation into the suitability of the Android smartphone platform to serve as a base for site survey applications. Lessons learned are shared based upon development and validation of a prototype application. The prototype application is Solar Survey, a free, open-source application for Android-based smartphones that allows site surveys to be performed. The app uses sensors built into the smartphone to make measurements of the horizon. The measurements may be output in a format suitable for use by System Advisor Model, or other computer tools, to perform more detailed photovoltaic system modelling and economic calculations. In addition, the measurements can be used within the app itself to provide estimates of the available irradiance using the Perez, or other tilted irradiance model. Optimum orientation (relative to irradiance) can be computed for both the raw meteorological data and including the effect of shading. The irradiance and shading calculations were validated against results produced by System Advisor Model. Horizon measurement uncertainty was estimated using repeated measurements of a fixed horizon. It is hoped that through the open-source code and documentation of the methodology in public literature, Solar Survey may serve as a research platform for solar site assessment, and promote further analysis of the accuracy of similar tools.