I'm not sure if this is a bug or not. If I put my Mac in "sleep" mode with a full battery and Parallels is open. The next morning (8 hours later) my battery is down to 20% and activity monitors shows that Parallels has used 50% of my battery while the system was in sleepstate, the other energy hog was activity monitor itself.. I would expect that if the Mac is put to sleep: Parallels should completely power down.
Hello, did you shut your VM down before putting your mac into the sleep mode? Could you please provide us with the screenshot of VM configuration->Options-> Start up and shutdown tab?