An FPGA based solar tracking algorithm

Advances in the algorithms of sun tracking systems have enabled the development of many solar thermal and photovoltaic systems for a diverse variety of applications in recent years. Compared to their traditional fixed-position counterparts, solar systems which track the changes in the sun’s trajectory over the course of the day collect a far greater amount of solar energy, and therefore generate a significantly higher output power.This work is aimed at building a Field Programmable Gate Array (FPGA) based stand-alone solar tracking system. The idea of the proposed algorithm is based on astronomical equations to determine the position of the sun in the sky during any time of the day by calculating the altitude and azimuth angles for the two tracking axis. The presented algorithm of the two axis tracker does not use light sensors, but instead is based on an FPGA chip. Especially large PV areas can benefit by this solution, replacing a large amount of light sensors with only one FPGA chip to control all the modules. In order to reduce the design complexity and obtaining reliable functional relationship for interpolating, predicting, or determining the rate of change of one variable with respect to another, some of the astronomical equations like equation of time and declination angle were approximated using spline functions, because of spline stability and calculation simplicity, the accumulated errors were approaching zero over the year and made the programming task easier. The general nature of the algorithm makes the FPGA to be the best choice for such application of tracking system because the occupied slices of the FPGA equal to 687 and this makes the program fit to any FPGA device that has a minimum number of pins equal to the total number of input / output of the tracker chip, beside this advantage the chip will be valid for all tracking periods.
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