An operation analysis is presented for a photovoltaic system consisting of the photovoltaic generator, the battery, the light, and the heater. An optimal resistive load for lighting is determined according to the characteristics of the battery. The working domain of the battery is marked out to display the range of the battery charge supplied by the photovoltaic generator. Before sunrise and after sunset, the battery supplies power to the light with an optimal resistive load. When the sun is above the horizon but sunset or not sunrise for the tilled photovoltaic module, the system is at rest. If the beam radiation is really incident on the surface of the module and induces a characteristic inside the working domain, all power will charge the battery. Once the characteristic is outside of the working domain, the resistive load is chosen to balance the currents of photovoltaic generator, battery charge, and heater. It is the only situation of concurrence. If the open-circuit voltage of the photovoltaic array under insolation is less than the zero-current voltage of the battery at the fractional state of charge, or if the battery is at full charge, the battery is disconnected from the photovoltaic system and the power output of the photovoltaic array to the heater is found by the method of maximum power point tracking. (C) 2011 Elsevier Ltd. All rights reserved.