The Sense Home Energy Monitor costs $299 (£240 and AU$390 at the current exchange rate).
The installation should be handed by an electrician since it requires opening the electric panel.
Sense tracks your home's energy usage in real time.
Track the total energy your home is generating at any given time and let Sense detect individual devices for itemized stats.
The Sense app makes it easy to view your total usage -- but it can take weeks for it to differentiate among appliances.