If the problem persists after trying to start the installation all over again from the start you might need a 3rd party drive partitioning tool to remove what was placed on the drive and now unreadable by the Windows installer. If it comes to that and you need a drive tool the Linux tool known as GParted will create the new primary needed while the installer later sees it formatted.
The 0.3.3.0 and 0.3.2.0 releases of the free Linux tool are "platform independent" meaning cross platform between various OSs. SO far no newer version of those has been released despite other updated versions.
http://sourceforge.net/project/showfiles.php?group_id=115843&package_id=173828
For general use the instructions along with screenshots can be reviewed at
http://gparted.sourceforge.net/larry/generalities/gparted.htm Some additional screens are seen at
http://gparted.sourceforge.net/screenshots.php
The sudden loss of power simply interrupted the installation process and likely no damage was seen unless you happened to see a large surge especially typical during an electrical storm. Otherwise it's likely a simple glitch in the installation being seen.
If you should happen to need a 3rd party tool GParted is downloaded as an ISO type disk image and burned onto a cd-r and made bootable. Free ISO capable burning programs are available like Deep Burner, BurnOn, and an updated free version of StarBurn found at
http://www.rocketdivision.com/download_starburn.html