Abstract: The temperature correction coefficient in a formula for estimating the generated energy of a solar cell is corrected in the negative direction as the mean monthly ambient temperature increases. For an amorphous silicon solar cell, the generated energy is expected to be smaller than the actually generated energy. To prevent this, a correction coefficient which increases as the mean monthly ambient temperature becomes high is calculated on the basis of the mean monthly temperature at the solar cell installation site. The generated energy is estimated from the mean solar radiation at the installation site, the calculated correction coefficient, and the rated power of the solar cell. With this arrangement, the generated energy of an amorphous silicon solar cell or a photovoltaic power generation apparatus can be more accurately estimated on the basis of the installation site.

Abstract: A power source apparatus includes a power generation device, a battery and an overcharge protection circuit. The overcharge protection circuit includes a shunt circuit, including a switching device for short-circuiting the power generation device when an input signal is at an `L` level. A reverse current protection circuit prevents an electric current from reversely flowing to the power generation device and/or the shunt circuit. A voltage detection section detects the voltage of the load or between the poles of the battery. An overcharge judgement section outputs an `L` level to the switching device when the voltage value detected by the voltage detection section surpasses a preset voltage value. When the voltage across the battery surpasses a predetermined value, the power source apparatus is short-circuited by the overcharge protection circuit, and therefore it is possible to prevent overvoltage from being applied to the load.

Abstract: An object of the present invention is to provide an insulation state measurement method and a judgement apparatus for a power conversion system, which can monitor the insulation state of an electric path with one end to which a power scarce is connected, or the power source itself in a non-use state of the power source, and can prevent an unexpected failure.A solar cell array connected to one end of an electric path is set in a non-grounded state upon operation of a change-over switch, and a measurement switch which receives an operation command from an operating circuit temporarily applies a high voltage to the electric path. A current detector detects a weak current flowing through connection lines, and supplies detection data to an insulation judgement unit. The insulation judgement unit calculates the insulator resistance on the basis of the magnitude of the applied voltage, and the magnitude of the weak current detected by the current detector.

Abstract: Even when a plurality of dispersed power generation systems are connected to a utility gride, an islanding-operation prevention apparatus can easily and assuredly prevent an islanding operation of each dispersed power supply constituting the corresponding dispersed power generation system. The apparatus includes a breaker provided between the utility gride and a dispersed power supply, an electric-power-value detector for detecting a value of electric power from a power line connected to the utility gride, a switch for electrically connecting or disconnecting an electric-power changing device for changing the value of electric power to the power line in accordance with an output from a pulse circuit, and a controller for controlling the breaker in accordance with the width of fluctuations of the value of electric power during the connection or the disconnection. A dispersed power generation apparatus and a dispersed power generation system uses such an apparatus.