The factories use "Low Lead Glass". Regular glass has lead in it. A lot of the power the cells makes comes from frequencys we can't see, and the lead stops much of this potential power from getting to the cells.
Where do you get it? I have no idea!
I also thought about getting them for a long time. I kind of figured on front of cell to low lead glass with a tiny dab of silicone, then 1/4 or 5/16" marine plywood or plexiglass with a good layer of silicone, carefully placed on the back.
Will it work? I have no idea!
If I get time and money, that's what I'm going to try.
If you go up to say 40 cells you could improve low light output, a little. Otherwise, you have to step up to 2 strings of 36.
If all goes well, you'll have a 50w 'rated' panel, output about 38w.