An Outline for Economical and Technical Analysis of Solar Panels for Agricultural Uses: A Case Study on Texas Weather Conditions

Aims: To outline the necessary steps in the evaluation of solar panel systems in agriculture.

Study Design: Using the outline proposed, GaAs and Si solar panels were evaluated under central Texas weather conditions.

Place and Duration of Study: Bioenergy Testing Laboratory (BETALab) between January and August 2013 in College Station, Texas.

Materials and Methods: The study includes an outline on how to do a technical and simple economic comparison between solar panels. The outline includes the solar panel efficiency, required area, installations and power generation costs and simple payback period. To exhibit the application of the outline, two different photovoltaic systems were compared (silicon (Si) PV panels and the gallium arsenide (GaAs) PV panels). The solar panels were compared simultaneously, taking measurements of voltage and current automatically in College Station, Texas.

Results: The GaAs solar panel showed conversion efficiency (18.36%) higher than Si panels (14.02% Si); however, it also has a capital cost ($3/Wp) higher than Si panels ($2/Wp). The study suggested that both panels are viable alternatives for energy independence in a small farm or ranch application. The final selection will depend on the economic alternatives and power necessities of the farmer or rancher. In this study, the GaAs have provided less payback period (6.8 years) compared with 7.5 years for the Si units using various assumptions. The larger efficiency of the GaAs (4%) unit translated into a better payback period despite its higher initial installed cost.

Conclusion: The technical and economical outline proposed in this paper was useful to decide between GaAs and Si panels using basic economic assumptions. However, this paper did not recommend a specific solar panel over the other in every situation. Each situation needs to be analyzed individually taking in consideration geographical situation, government subsidies, rebates and tax credits.