Solar Panel Efficacy vs. Altitude in an Urban City Environment

Abstract

In light of current issues of global warming, pollution, and fossil fuel depletion, alternative and renewable energy sources are increasing in desirability. Among these, solar energy is a popular option. However, it is hypothesized that particulate pollution in urban atmospheres limits photovoltaic (PV) efficacy both in accumulated grime and also in altitude via sunlight attenuation. The objective of this study is to measure photovoltaic power output near solar noon at multiple heights within a city environment to determine the influence of altitude on power output. Building rooftops between 200 and 800 feet were sampled simultaneously with a ground level control within a broad university courtyard. Days having no cloud cover were preferentially chosen. Other factors to consider include the “urban heat island” effect and water vapor in the air, so meteorological parameters were measured simultaneously to reduce confounding errors. Multiple repeated tests were conducted to increase confidence, especially since the effect was anticipated to be small in magnitude. Additionally, students affiliated with the project completed surveys to assess how their involvement impacted their learning of experimental design and procedures. Students who chose not to participate were also surveyed to provide a control group. Comparisons in the data are drawn on a power to ambient light ratio to minimize bias between the PV panels used for testing. Preliminary analysis indicates the effect of altitude is minimal within the parameters of this study. Analysis of our data did not significantly demonstrate an improvement in solar productivity at increased altitudes. However, the rigorous test methodology developed provides a means for quantitative analysis in cities with greater levels of pollution relative to the city tested. The survey of students indicated a positive correlation between participation in the project and the amount students felt they learned during the process.