A photovoltaic inverter control method includes steps of monitoring a
variation in output voltage of a solar battery by a power and voltage
monitoring circuit (51) and, when the variation occurs, accelerating or
decelerating an electric motor (3) to maximize the output voltage of the
solar battery (1), whereby the electric motor for driving, for example, a
pump and a fan by the solar battery as a power source can be driven by a
photovoltaic inverter always at the maximum power point of the solar
battery.