if it hasn't been created, yet; then glass selection is crucial. I have built a few of these "wall hangings" and have found that opaque wall is about the only way to go. The trick is to NOT hold the glass up to the light when selecting.
Now, I assume the panel is done. Are you asking how to HANG it on a wall? Or are you asking the best way to get some light behind it without a lightbox?
You can always hang it form the ceiling, just few inches out from the wall. Then run some small directed lighting above it and aim for the space between. This is add some needed light. When hanging a panel, consider the weight. If it is too large, you MUST build some sort of framing. Many stained glass outlets carry oak U framing designed to take leaded panels. The largest that we have hung without a wood frame was about 3' x 3'. We had to fashion special hangers to grab the zinc more securely than standard loops.
there are a variety of stand off brackets and clips available for stained glass ... check with your local supplier or have them contact one of the wholesalers for a list of what is available ... our favorite is a chrome barrel bracket that you can screw to the wall, set the glass in and tighren the set screw ... good looking and sturdy