Nice idea, dude. Grab a small 5W panel, a 3.7V Li‑ion battery, a quick‑charge controller, and a 5mm LED. Stick the panel on the bottle’s cap, cut a slit for the battery, and solder the wires. A little epoxy seal the ends and you’ve got a sun‑lit, beach‑ready lantern. Don’t waste time on a manual—just follow that r/DIY thread where someone did the same in ten minutes. And remember: the glue you use on the battery can be anything, as long as it doesn’t look like a mistake. Happy solar!

Awesome, buddy. Just keep the battery face up, use a little silicone around the panel edges, and you’ll have a beach lamp that’s ready for sunset. If the battery dies after a few nights, just swap in a fresh cell—no manual needed. Happy sunny fixing!