Cubic Composite Sensor with Photodiodes for Tracking Solar Orientation

A cubic composite solar sensor with photo diode is proposed for tracking the relative solar orientation. The proposed solar sensor composes of five photodiode detectors which are placed on the front, rear, left, right, and horizontal facets in a cubic body, respectively. The solar detectors placed on five facets can detect solar power of different facets. Based on the geometric coordinate transformation principle, the relationship equations of solar light orientation between measured powers with respect to various facets can be conducted. As a result, the solar orientation can be precisely achieved without needing any assistance of electronic compass and extra orientation angle corrector. Eventually, the relative solar light orientation, the elevation angle, and azimuth angle of the solar light can be measured precisely. 1. Introduction Recently, the renewable energy has drawn great attention due to energy shortage. Many renewable energy researches are focused on solar power system [1–4]. For the solar system, a precise sensor is indispensable to tracking the sunlight orientation. Many studies have been focusing on solar tracking technique. However, there still exist some drawbacks on solar light tracking apparatus. Solar light tracker can, in general, be classified into mechanical and electronic category [5, 6]. Mechanical solar tracker experiences much fault probability and maintenance cost, electronic solar tracker depends highly on electronic compass accompanied by perpetual calendar, and precise perpetual calendar heavily relies on complicated computation through the usage of internet, thus leading to inconvenience in application [7, 8]. Therefore, to develop an electronic solar light tracker, without needing electronic compass and perpetual calendar, is essential to researchers and solar power applications. An electronic solar light tracker can only be realized through the application of photo detecting devices. There are many photo devices such as photodiode, photo transistor, and resistive CdS components. The CdS components are passive components and usually cannot play the key role in a precise measurement. In this paper, the active photodiodes with wide measuring range and fast response and low dark current are applied as a solar sensor to measure the solar orientation. The solar light orientation information should consist of the relative elevation angle and azimuth angle between solar source and photo detector. For collecting lights from all possible orientations, this paper employed five photodiodes to compose a cubic structure photo