A solar water heating system consists of:

• solar collectors in which fluid is heated by the sun,
• a storage tank that allows the sun’s heat to be captured during the day and used later on, and
• a circulation system that moves the heat from the collector to the storage tank.

A tempering valve, which adds cold water to hot, must be installed to keep hot water at faucets and showers below scalding temperature. 

All solar water heating systems in Oregon must be protected against freezing in winter and overheating in summer. 

The most common solar water heaters in Oregon are closed-loop, or “indirect,” systems, which circulate a special fluid through the collector to a heat exchanger that transfers heat from the fluid to the potable water in the storage tank.  An open-loop, or “direct,” system circulates potable water directly through the collector.  Open-loop systems are more simple, but risk freezing and buildup of mineral deposits in the collector from hard water.

Systems will last 20-30 years or more if properly maintained.