This paper proposes a new sliding mode controller for maximum power point tracking of photovoltaic cells. By defining a suitable sliding surface, the proposed control law does not require reference voltage/current. The proposed system is based on the one-loop control schemes which makes its implementation easy. Stability of the proposed system is ensured using Lyapunov stability theorem. It is proved that the proposed control system is robust to system uncertainties. Moreover, a new state-dependent control magnitude is designed which suppresses chattering of the system. A traditional sliding mode controller is considered in order to compare the results of the proposed system. Simulation and experimental results are used to evaluate the robustness of the proposed system. It is shown that the proposed system is robust to system uncertainties, environment changes and load variations. (C) 2016 Elsevier Ltd. All rights reserved.