Can I get some more infomation about measuring Electrical Power?
Sure. The standard way to get the WEL to read power, is to install a Wattmeter from Continental Control Systems (see link) at your power panel and then feed the pulse outputs to the WEL. The basic WNB (Advanced Pulse WattNode) meter can do 1-3 phase measurements and also provide net metering data. Another option exist (-PV) that will enable you to add a dedicated channel for PV or other device. I like the WNB meter because it has a high frequency output option (-300Hz) which enables the WEL to do accurate instantanious load measurements.