Abstract: This invention provides a method for suitably using a method for collectively receiving at a high voltage and distributing at a low voltage in collective housing. In this method for collectively receiving at a high voltage and distributing at a low voltage to a plurality of users, a distribution control part for collectively receiving power and distributing the power at a low voltage includes a server 12 and a control device 131 for controlling information on power consumed by the users. The control device 131 and the server are connected via a network. The server 12 grasps a maximum current capacity necessary for each user, determines a contracted current depending on the grasped maximum current capacity, and distributes power to each user.

Abstract: A system for reducing power without making users feel inconvenience and discomfort in collective housing or the like. The system includes a plurality of air conditioners and a central control unit connected with the air conditioners via a communication line. The central control unit controls the plurality of air conditioners to operate in time or alternately to prevent electric current concentration.

Abstract: A controller of a data communication apparatus according to the present invention stores information on each successful and unsuccessful data communication, a season, a data of the week, a time, and a data communication rate of the communication for each site in a data memory. The controller reads out a data communication rate at which a data communication succeeded from the data memory and directs a modem to conduct a communication at the data communication rate. A data communication is conducted at the directed data communication rate. These procedures ensure a secure link between sites and a secure data communication irrespective of a line distance between the sites etc.

Abstract: This invention provides a method for suitably using a method for collectively receiving at a high voltage and distributing at a low voltage in collective housing. In this method for collectively receiving at a high voltage and distributing at a low voltage to a plurality of users, a distribution control part for collectively receiving power and distributing the power at a low voltage includes a server 12 and a control device 131 for controlling information on power consumed by the users. The control device 131 and the server are connected via a network. The server 12 grasps a maximum current capacity necessary for each user, determines a contracted current depending on the grasped maximum current capacity, and distributes power to each user.

Abstract: This invention provides a system for reducing receiving power without making users feel inconvenience and discomfort in collective housing or the like. The system includes a plurality of air conditioners and a central control unit connected with the air conditioners via a communication line. The central control unit controls the plurality of air conditioners to operate in time or alternately to prevent electric current concentration.

Abstract: The present invention prevents an increase in an overvoltage and increases an optimum operating voltage of a power inverter. A photovoltaic power generation device is provided with a solar cell device 1, a power inverter 2 for inverting output from the solar cell device 1 into AC power, a current path circuit 3 connected in parallel between the solar cell device 1 and the power inverter 2, and a current detection circuit 4 for detecting a current feeding back to the solar cell device 1. When a current detected by the current detection circuit 4 reaches beyond a predetermined current value, the current path circuit 3 is cut off.

Abstract: A device for operating inverters according to the present invention can operate a plurality of inverters for converting DC output from a DC source such as a solar cell to AC output efficiently without relying on a particular inverter. The plurality of inverters are connected to the DC source through switches. DC output from a DC source is measured by a measuring device to determine the number of inverters to be operated on a basis of the output result from the measuring device. The inverters to be added or cut off are determined among the plurality of inverters at random on a basis of the random number and switches of the determined inverters are turned ON or OFF in order to select inverters to be operated.

Abstract: A device for operating inverters according to the present invention can operate a plurality of inverters for converting DC output from a DC source such as a solar cell to AC output efficiently without relying on a particular inverter. The plurality of inverters are connected to the DC source through switches. DC output from a DC source is measured by a measuring device to determine the number of inverters to be operated on a basis of the output result from the measuring device. The inverters to be added or cut off are determined among the plurality of inverters at random on a basis of the random number and switches of the determined inverters are turned ON or OFF in order to select inverters to be operated.

Abstract: The present invention is directed to a photo-voltaic apparatus comprising a photo-voltaic module having a plurality of photo-voltaic cells, and an inverter for converting a direct current output generated from the photo-voltaic cells into an alternating current and outputting the alternating current, the inverter being mounted on a surface opposite to the light receiving surface of the photo-voltaic module with a clearance provided therebetween, so that heat self-generated by the inverter can be efficiently radiated, and heat from the photo-voltaic module is not transferred to the inverter.