I bought several cheap Hampton Bay garden lights at Home Depot a few years ago. Part number 498-959. The clear plastic diffuser that supports the electronics has become brittle and fell apart. I suspect its the UV from the sun and has broken down the chains of molecules of the plastic. Instead of throwing them away, I discovered they will fit on top of a Ball canning jar with little effort. First remove the four Philip head screws that hold the two halves of the solar head.
There are four holes already in the solar head. Use two of them with 6-32 machine screws and nuts to attach the canning jar lid. You can see the screw heads in the photo below just inside the lid's rim. In the photo above, you can see the nuts of these two screws
Now the glass won't fall apart like the plastic in the sun. You may need a little caulk around the edges to seal out water. I intend to place mine in my window to light up at night, so theres no water proofing required. If you want more info about the schematic inside, go here to my webpage. I also wrote about the plastic falling apart problem in this 2007 blog.