Two FPGA-oriented high speed irradiance virtual sensors for photovoltaic plants

Knowing solar irradiance value allows an optimized management of photovoltaic (PV) power plants in terms of produced energy. Unfortunately, although sensing temperature is easy, the measurement of solar irradiance is expensive. In this paper two circuit architectures for the estimation of the solar irradiance based on simple measurements are proposed. They are thought to be part of a centralized system implemented on FPGA (Field Programmable Gate Array) for sensing and monitoring of solar irradiance in a whole PV plant. The FPGA centralized architecture could allow for a real time irradiance mapping by exploiting information coming from several low-cost measuring circuits suitably allocated on the PV modules. Validations on real irradiance data collected by the U.S. Department of Energy's National Renewable Energy Laboratory are presented.