Solar Heat & Hot Water

Solar hot water systems can produce most of your family’s hot water during much of the year. Hot water systems are the most affordable type of active solar energy systems and are a good entry point into using renewable energy at your home.

The basic components of a solar domestic hot water system are the collector, a storage tank and a pump to circulate a heat transfer fluid between the two.  

The two main types of collectors are evacuated tubes or flat plates. In the Pacific Northwest, we have found that the vacuum tubes are more efficient at gathering heat during the overcast days of winter.   

Evacuated tubes, sometimes called “heat pipes”, are 6 to 7 foot glass tubes that have had most of the air removed with a vacuum pump. Inside is a copper absorber plate that absorbs heat from sunlight. The heat is convected upward into a copper condenser bulb at the top end of each of the tubes. The heat transfer fluid circulation loop goes through a single copper pipe inside of an insulated manifold box into which the heat pipes are inserted. The heat is conducted into the circulating fluid and pumped to the tank location. A heat exchanger either inside the storage tank or external to it transfers the heat into the domestic hot water. 

Solar thermal collectors can contribute to space heating using hydronic in-floor heat distribution systems. The high efficiency vacuum tubes do produce significant heat during the cold, overcast days of the Northwest’s heating season. However, the collector surface area needs to be oversized to contribute substantially to space heating, which means that the system will produce more heat than needed for domestic hot water uses during the summer months. A swimming pool or hot tub can be a good use for surplus heat during the summer months.

Please contact us for more information about these systems.