Researches Of A New DSP-Based Solar Angle Detecting System

The solar angle is measured by the digital signal or analog signal based measurement with many photosensitive components (such as photovoltaic cell, light-sensitive diode) which are used as sensitive element in the solar-detecting device. Considering the digital signal based measurement with low precision and using many photosensitive components, the analog signal based measurement is widely adopted. In practical application, the reflected light around the solar-tracing device and the characteristics difference between photosensitive components will affect the results in analog signal based measurement.To solve above-mentioned problems, a new measurement method is put forward in which the solar angles are calculated through the short circuit current curves with rotation of a single photovoltaic cell. The angles are calculated by the phase of fundamental wave extracted from DFT in different characteristic of short circuit current while sun ray radiate the facade and back of the cell with cell’s rotation which eliminates the affection of reflection. In the system, the photovoltaic cells are rotated round X, Y and Z axes. The azimuth of sun is calculated through the single photovoltaic cell rotated round Z axe while the altitude angle of sun is calculated through the single photovoltaic cell rotated round X axe. And the third photovoltaic cell rotated round Y axe is used only when the altitude angle is0or π. By this way, the problem caused by the characteristics difference between photosensitive components can be avoided, and the result is more accurate.At the beginning of the paper, the feasibility of the new measurement method is demonstrated and the system design based on DSP is put forward. According to the system design, the hardware and software of the system are designed and implemented. The test results of the system are presented which shows that the system has the advantages such as simple structure, high detection speed and precision. At the end of paper, some suggestions for system optimization are provided.