Hybrid maximum power point tracking techniques: A comparative survey, suggested classification and uninvestigated combinations

Maximum Power Point Tracking (MPPT) of Photovoltaic (PV) arrays is inevitable to maximize the power transfer and improve the system efficiency. Many MPPT techniques were proposed in literature with diverse algorithms and methodologies; offline, online, estimation, computational and intelligent methods were examined to drag the system operating state to the maximum power point (MPP) under different weather conditions. High accuracy, fast tracking speed, ease of implementation and ability to track the Global Maximum Power Point (GMPP) under partial shading conditions are the most important and desirable yet rather complementary features of any individual MPPT technique; meaning, high accuracy in most cases is associated with slow tracking speed as in the online Perturb and Observe (P&O) method. Most single or individual MPPT techniques manage to achieve one or two of those desired aforementioned traits, while fail to accomplish the others. Thus, Hybrid MPPT systems are introduced, combining two individual MPPT techniques and aiming at attaining in the overall the merits of each individual technique while eliminating their drawbacks. Hybrid MPPT surpassed in performance individual techniques whether in combing accuracy with speed or even tracking the GMPP under partial shading at no added complexity. For this reason, this work focuses mainly on Hybrid MPPT techniques, starting by the most common individual MPPT methods and surveying 20 examined Hybrid combinations listed in literature with a proposed classification and a comparison of their overall performance. Moreover, it presents, via a Conceptual Map (C-Map),1 a suggested pattern followed into combining two MPPT techniques into one Hybrid MPPT system. In addition, a list of uninvestigated Hybrid combinations is proposed exploring further potential enhancement.