Here are a few different steps to lower the voltage of a PS3:
Step 1: Turning on Automatic Shutoff
Step 2: Lowering Your Output Resolution
Start by scrolling down to Display, click on it, then go to Video Output Settings (as you can see in my third photo, I am outputting my PS3's resolution at 1080i).
Choose what connection you are using, and you will come to the screen of the main picture (below). Now check the lowest resolution possible to save the most power. The lower the resolution the least power the TV is using.
Your screen will go black and will flash back. It will now ask you for 4:3 or 16:9 I'd say 4:3 uses less power. Press X to confirm.
This saves a bit of power, but can add up overtime.
Step 3: Using ScreenSaver
This is good to reduce voltage when not playing.
Step 4: Disable Your Wi-Fi/Internet Connection
Scroll down to Internet Settings.
Then click on Internet Connection>Disable.
Disabling WiFi (and even Online) can save your PS3 a bit of power when communicating between your Router or your Internet Modem.
You can also save power by not playing Online Games on PS3 or using its Web Browser.
Step 5: Completly Turning Off System
Ok either head over to User>Power Off, Hold Down the PS button on the controller until it comes to a menu and then press Turn System off, or Manually do it yourself.
Now you will see a switch behind the system. Press it and it will completly turn off the system. You will notice because the red light on the front pannel is no longer there, and you cant turn off/eject disc from the system without flipping the switch again.
Ok that was simple! By doing this you are eliminating all power going into the PS3. This is much greener and should be down on a regular basis (overnight, weekend trip, weeklong trip, moving away and for some messed up reason leaving your PS3 plugged in etc.)
Step 6: Take Out That Optical Disc!!
(| recently had to send my PS3 in because the BD Lazer blew out)