The panels I have see 14.6V for part of the day when the solar is charging. Probably a minimum of 13.6V. Forum member "Sparky" tested similar panels and operated them at 15V.
Of course, the LED solutions offered by Asian sellers are not all the same. That is why buying a few to test in different locations is a good exercise. If you get ones that fail, you're only out a few bucks. Buy from a different seller. A buyer can do this a few times and still be ahead of buying high priced LED's from sellers like Superbright LED, or similar.
IIRC, the E Bay vendor I had good luck with is named 2011_LED or something like that. I also bought good ones from a different vendor.