Introduction, evaluation and application of an energy balance model for photovoltaic modules

Here we introduce a new energy balance model that accurately simulates the complete diurnal dynamics of photovoltaic (PV) thermal behavior with routinely available meteorological input. The model is evaluated extensively against observed module surface temperatures (day and nighttime), electrical output, and sensible heat flux measurements. It is demonstrated that different tracking systems have a significant effect on module temperatures and sensible heat fluxes by modulating the total radiation received on the PV surface. A model intercomparison study indicates significant improvements in the representation of module temperatures compared to an earlier study, the commercial software PVsyst and the Python package PVLIB. A sensitivity study demonstrates a considerable effect of the PV conversion efficiency and longwave emissivity on sensible heat fluxes emitted by the module. The model is available as a stand-alone program (UCRC-Solar) written in Python and planned to be implemented in mesoscale meteorological models to study the geophysical impacts of PV arrays at larger spatial and longer temporal scales.