If it's just the basics that you are looking for in a power monitoring system, then an RS-485 twisted pair network, MODBUS driver and a program such as MICROSOFT EXCEL® are the only items necessary. Setup is easy and startup cost is minimal.
A MODBUS driver, such as KEPServer, is installed on the computer and operates in the background much in the same way that a printer driver operates in the background allowing you to print documents with the click of a button. Once installed and running, the MODBUS driver continuously monitors all of the trip units connected to the computer and makes that data available to other software programs running on the same computer using Dynamic Data Exchange (DDE). KEPServer can be user configured to operate serially with trip units daisy-chained directly to the PC or configured for MODBUS over TCP/IP to communicate over a Local Area Network.