太たい陽よう熱ねつ温おん水すい器き

Meanings

1

solar water heater

A device that uses solar thermal energy to heat water for domestic or commercial use.

water

器utensil, vessel, receptacle

太たい陽よう光こう発はつ電でん
Refers to solar photovoltaic power generation, not water heating.
給きゅう湯とう器き
A general water heater, often gas or electric, not necessarily solar.

Compound of 太陽 (sun), 熱 (heat), 温水 (warm water), and 器 (device).