ABSTRACT:The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading and array configuration. The PV system exhibits a non-linear I-V characteristic and its unique maximum power point on the P-V curve varies with insolation and temperature. Often the PV array gets shadowed, completely or partially, by passing clouds, neighbouring buildings and trees. This situation is of particular interest in case of large PV installations such as those used in a distributed power generation scheme and residential PV systems. Under partially shaded conditions, the P-V characteristic becomes more complex with multiple peaks. Conventional Maximum Power Point Tracking (MPPT) techniques fail to reach global peak power point and tend to stay in local peak power point which significantly reduces the efficiency of the PV system. This paper mainly focuses on extracting the maximum power from PV array under partially shaded conditions by executing improved hill climbing algorithm to identify the global maximum power point (GMPP) and SEPIC is used as a dc-dc interface. Simulation results have been presented to verify the performance of the proposed GMPPT technique. KEYWORDS:Maximum power point tracking (MPPT), Hill climbing algorithm, Photovoltaic I-V characteristics, Global Maximum Power Point (GMPP) I.INTRODUCTIONWith a Spurt in the use of non-conventional energy sources, Photovoltaic installations are being increasingly employed in several applications. However a major challenge in using a PV source is to tackle its nonlinear output characteristics which vary with temperature and solar insolation. The characteristics gets more complicated if the entire array does not receive uniform insolation as in partially shaded conditions resulting in several multiple peaks. This reduces the effectiveness of the existing maximum power point schemes due to their inability to differentiate between the local peaks and global peak [5]. Nevertheless, it is very important to understand and predict the P-V characteristics of PV array to use a PV installation effectively under all conditions. When the individual modules or cells of a PV panel have non-uniform current generated due to variation in irradiation (i.e partial shading) known as "mismatch condition", the overall PV characteristics may present multiple peaks. The global MPP occurring at a low voltage level and local MPP being placed at a voltage quite close to that one at which the unique MPP normally occurs in the uniform irradiation case makes it difficult to directly apply the gradient based MPPT control algorithms.In [1], the technique proposed consists of a two-stage MPPT along with Voc and Isc measurement. Though it is very simple to apply, additional circuits are required to measure Voc and Isc. In [2], MPPT based on P&O in addition to a subroutine called Global Peak(GP) subroutine was proposed. Though this does not require any additional circuit, it guarantees tracking the global peak power point only when multiple peak power points happen to be on ...