A solar heated hot tub is great if you also want to install either a domestic
hot water solar system or a solar heating system for your home as it
allows any excess heat to be used. In other words, it’s great if you do it in conjunction with the installation of a Solar Hot Water (SHW) system to capture any excess heat.
Building an SHW just for a hot tub by itself is not cost effective. Also, just heating a hot tub or pool disallows the Federal Tax credit.
Basically involves routing your tub water thru a heat sink. The heat sink uses the excess heat genetated from your SHW after your domestic hot water is satisified.
So, bottom line, if you’re going to install a SHW system for your home, and you want to capture any unused heat, you might as well route that unused heat through your hot tub. Going green doesn’t necessarily mean sacrifice after all!