Dual-axis solar tracker with satellite compass and inclinometer for automatic positioning and tracking

Abstract

For increasing the solar energy harvesting performance, any solar tracking system must track the sun at the right angle during periods of daytime. We proposed an enhanced solar tracking instrument to solve the issues of low sunlight incident angles and manual orientation/elevation calibrations. This novel tracker used two Global Positioning System (GPS) receivers with Real-Time Clock (RTC) forming a satellite compass and combined with an inclinometer to follow the sun trajectory correctly without manual aligning the heading of system to orientation of North-South. Such a dual-axis instrument was controlled by a microcontroller unit (MCU) integrated with servo-motors, satellite compass and inclinometer. The embedded Solar Position Algorithm (SPA) can determine the angles of the sun vector at the given date, time and geographical information from the satellite compass. The power generated by the proposed tracking instrument, compared with a fixed-tilted photovoltaic (PV) tracker, was proven in scenarios of fixing, rotating and moving. The proposed solar tracker with satellite compass after field measurement extracted more energy than the fixed-tilted solar tracker under fixed location with mostly clear day 35.91%, in different locations with clear day 38.72% and 38.40%; in heading variation and moving conditions were 60.00% and 113.70%. Therefore, this solar tracker is not only suitable for PV grid but also well suitable for mobile vehicles with keeping the panel aligned with the sun automatically, whether geographical position in northern or southern Hemisphere independently and without solar panel tilted orientation adjustment to achieve the robust, convenient and reliable requirements.