Solar Hot Water Systems – One and Two Tank Systems
Solar hot water systems generate hot water for domestic and commercial uses. Solar hot water systems are eco-friendly, require very little maintenance and are cost effective to operate. They require very little maintenance. The components of solar hot water systems should be checked and possibly replaced every ten years by a solar energy contractor.
Solar hot water systems generally consist of solar collectors, water storage tanks and piping for feed and return lines.
Two tank solar water heating systems consist of a well insulated, solar storage tank and a pressurized conventional water heater. Hot water from the collectors is piped to the solar storage tank and is stored until needed. When hot water is in use in the home, this pre-heated water in the solar storage tank will feed into the conventional water heater to replace the hot water used. Conventional water heaters also provide a backup system to solar water heating systems when water temperature is below the minimum temperature setting.
One tank solar water heating systems use a conventional pressurized tank. This tank, with its backup water heater, acts as the solar storage unit. Hot water from the collectors is piped into the tank, into the lower portion of the tank, to replace hot water that is being used from the top of the tank. The backup water heater will engage if necessary.
Solar Hot Water Systems – Types of Solar Collectors
Domestic solar hot water systems use two types of solar collectors, flat-plate collectors and evacuated-tube collectors.
Flat-plate solar collectors consist of an insulated box which contains a dark absorber plate under one or more glass covers. Water or a glycol mixture is heated as it flows through piping below the absorber plate and out to the solar storage tank. These are the most common type of solar collectors used in solar hot water systems.
Evacuated-tube solar collectors contain parallel rows of transparent glass tubes. Each of the tubes contains a glass outer tube and a metal absorber tube attached to a fin. The fin absorbs solar energy. Air is evacuated and a vacuum is formed which prevents heat loss. Evacuated-tube collectors are more expensive than flat-plate solar collectors.
Solar Hot Water Systems – Closed Loop and Open Loop Systems
Solar hot water systems utilize the natural resource of the sun’s radiation to heat water for domestic and commercial use.
There are two basic types of solar hot water systems, closed loop systems and open loop systems.
In an open loop solar hot water system, water from the home’s main water supply flows through the solar collectors to be heated. Heated water is then stored in the solar storage tank. An open loop system is the easiest solar hot water system to design, construct and maintain. An open loop system should not be used where temperatures can drop below freezing.
A closed loop solar hot water system uses a glycol antifreeze fluid that circulates from the solar collectors to the solar water storage tank. When the fluid is heated, it will flow through the heat exchanger and heat the water in the storage tank. A closed loop system may be used in any climate.