The widget shows an approximate current power use. There is a power gauge showing the estimation of the currently used power and the currently active sensor with the biggest power draw.
You can switch on logging in the options to diagnose unexpected power use. Currently the logging can capture the code running from timeouts and intervals and the power up and down of some devices. The captured times are probably not perfect but should be good enough to indicate problems.
Do not use trace logging for extended time, it uses a lot of storage and can fill up the flash quite quick.