A monitoring/control system is used for a solar power generation site in which a large number of solar modules includes a plurality of solar cell groups each including a plurality of solar cells, wherein power generation output from each of the solar cell groups is connected in parallel from a cell group controller to an in-module parallel connection line, and the in-module parallel connection line is connected in parallel from an optimizer to an inter-solar-module parallel connection line and is concentrated in a junction box. The monitoring/control system includes a relay terminal collecting data of the cell group controller and accumulating data of the optimizer, a server including a communication control device and carrying out an upload/download process of management/control data via a public telecommunication network between the relay terminal and a remote terminal at an integrated management site, and the remote information terminal installed at a remote site.