Control strategy for a dual-axis sun tracker based on a radiometric cube to maximize the power output of the PV system

Abstract

The use of solar energy as an energy source is essential to reduce greenhouse gas emissions. In a photovoltaic system, the use of a sun tracker can produce up to 40% more energy than a fixed system. However, it is important, especially in temperate climates, to have an effective control strategy that can adapt the movement of the solar tracker for all weather conditions. This work presents a new control strategy for a dual-axis sun tracker based on a radiometric cube with four photodiode sensors on its East, West, South and Zenith faces. The optimal direction that maximises the irradiance received by the sun tracker can be determined through the mathematical expression of the irradiances on the four faces of the cube, considering an isotropic model for the diffuse luminance of the sky. This new control strategy adjusts the movement of the solar tracker to an optimal position in all weather conditions. The proposed control strategy provides a 40.5% gain in energy output on a cloudy day compared to the standard chronometric sun tracking strategy. For periods of clear and highly variable sky, the difference between the two strategies is only 0.15% and 1%.