Turning sunlight into hot showers: best kits or hacks?

I’ve actually tried the “insulated box” thing around a 5-gallon tank last winter, and honestly, it was more hassle than it was worth. Even with spray foam and reflective wrap, the water barely stayed warm past sunset—just too little sunlight in December up here. I get the appeal of heavy-duty insulation, but unless you’re running a heat source overnight (which kind of defeats the “solar” part), I’d say it’s diminishing returns. As for sourcing parts, tracking down oddball fittings was a pain. Ended up cobbling together stuff from three hardware stores and still had to order a weird adapter online. If you’re not super handy, prefab might save you a lot of headaches, even if it means settling for less-than-hot showers in the dead of winter.