This paper presents a novel high-performance standalone photovoltaic (PV) lighting system which can provide functional illumination based on high power White LEDs. An improved incremental conductance Maximum Power Point Tracking (MPPT) method is proposed in PV system to maximize the photovoltaic array output power, irrespective of the temperature and irradiation conditions and of the load electrical characteristics. A novel strategy to charge the battery is designed from the analyses and comparison results. In order to provide a steady-state operating environment for high power White LEDs, a specially designed LED drive module is implemented. Further more, a self-adapting dimming control is designed to maintain a stable indoor illuminance. Experimental results show the performance of the proposed photovoltaic lighting system.

High power LED (Light Emitting Diode) has a wide application in lighting for its good features. In this paper, the electrical properties of LED are first introduced, and then a series-parallel connection of LEDs with more stability and reliability is adopted on the basis of the features of parallel connection and series connection. After that, a flyback circuit for driving high power LED group with a constant-output-current is investigated, and the parameters are designed. According to the driving method, a circuit prototype with an output of 10.0V/1.10A is fabricated and tested in rated load and overload conditions to verify its current stability. Experimental results show that the LED drive circuit has a high accuracy, good stability and high efficiency, suggesting that the proposed method might be practical for driving high power LEDs.