A hybrid solar panel maximum power point search method that uses light and temperature sensors

Abstract

ABSTRACT Solar cells have low eciency and non linear characteristics. To increase the output power solar cells are connectedin more complex structures. Solar panels consist of series of connected solar cells with a few bypass diodes, toavoid negative e ects of partial shading conditions. Solar panels are connected to special device named themaximum power point tracker. This device adapt output power from solar panels to load requirements and havealso build in a special algorithm to track the maximum power point of solar panels. Bypass diodes may causeappearance of local maxima on power-voltage curve when the panel surface is illuminated irregularly. In thiscase traditional maximum power point tracking algorithms can nd only a local maximum power point. In thisarticle the hybrid maximum power point search algorithm is presented. The main goal of the proposed methodis a combination of two algorithms: a method that use temperature sensors to track maximum power point inpartial shading conditions and a method that use illumination sensor to track maximum power point in equalillumination conditions. In comparison to another methods, the proposed algorithm uses correlation functionsto determinate the relationship between values of illumination and temperature sensors and the correspondingvalues of current and voltage in maximum power point. In partial shading condition the algorithm calculateslocal maximum power points bases on the value of temperature and the correlation function and after thatmeasures the value of power on each of calculated point choose those with have biggest value, and on its base runthe perturb and observe search algorithm. In case of equal illumination algorithm calculate the maximum powerpoint bases on the illumination value and the correlation function and on its base run the perturb and observealgorithm. In addition, the proposed method uses a special coecient modi cation of correlation functionsalgorithm. This sub-algorithm uses the error value between calculated and real maximum power point and onits base modi es correlation function coecients.Keywords: maximum power point tracking, light sensor, temperature sensor, correlation function, adaptivealgorithm, partial shading