The motion-detector water mechanism (aka ScareCrow) does not work. It's the biggest waste of money and isn't cheap! All the experts will tell you the same thing; any animal with half a brain will figure out the ScareCrow and trigger it so it can drink water from it instead of being scared of it.
There are only a few things you can do for raccoons, opossums and large birds like herons (all of which I've encountered as I have a koi pond in the backyard.)
First you can try a small mirrored ball and place a few of them throughout the yard. When an animal approaches, it gets scared of the reflection and thinks it's seeing a predator. These can be purchased from Art Knapp or Potters Nursery.
You can also add a REAL scare crow as it resembles a real person. These animals usually aren't afraid of many things; especially if they're nesting nearby. A scare crow however can act as a deterrent.
Lastly, these animals do have natural predators. Spreading the urine from a wolf (which can be obtained from your local pest removal company) will act as an effective deterrent.
These are the cheapest and easiest ways to remove a pest without having to trap the animal.
As for garden lights, if you're just using them for decorative purposes, I would suggest getting the solar LED color-changing lights with bubbles. They work great, look the best, last long and are cheap!
Available at JYSK for $5.99