those little cells work for me surprisingly well, even when in part shade. However, the lights are sooooo dim. If you need light to avoid tripping or stepping on something, I don't find them useful. If you're needing them to highlight a pot, plant, hardscape, then, yes. also could you install the cell up high in some kind of bare spot in your tree?
HD kits is all I've used. They've lasted 2-3 years.
I have found the inexpensive solar lamps to be minimally effective on my shaded driveway.
And they disintegrate pretty quickly for me, so were pretty useless after the first year.
There are supposedly higher quality solar units now, which I'm looking into.
But they seem pretty expensive. I'm reluctant to sink much money into them,
as my prior experience hasn't been very positive.
Otherwise, I think I'll have to hardwire electric lights.