The Solar Water Heater

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solar water heater

The solar water heater works by using the sun’s energy to heat water or a heat-transfer fluid. The solar collector and insulated storage tank make up these systems. In the case of a one-tank system, two sets of outlets and inlets circulate water through the tank and the heat transfer liquid through the water. Two-tank systems work in a similar manner but the water is preheated with solar energy before it enters a conventional water heater.

The Different Types of Solar Collectors

The solar collector is the component of a solar water heater system which harnesses solar energy and transforms it into heat. This heat is then transferred to water or a heat transfer fluid. 

One type of collector is the flat-plate collector. It is made of an insulated metal box that has a dark-colored absorber plate, with either a plastic or glass cover (which is known as the glazing). There is also a variation of this collector which does not feature any glazing. This variation has an unenclosed absorber plate made out of polymer or metal.

Integral collector-storage systems are also known as ICS or batch systems. They are made of an insulated glazed box which contains one or more black tubes or tanks. This organization of tubing is the preheating component of a larger solar water heater system. It works by heating cold water then sending it into a conventional water heater.

The evacuated tube collectors have a tendency to achieve very high temperatures (between 170°F and 350°F) which make them a prime choice for use in commercial and industrial applications. The collectors are made out of parallel tubes to reach this type of heat. Each tube contains a metal absorber tube attached to a fin and an outer glass tube. The fin draws in solar energy and prevents radiant heat loss. Between the outer and inner tubes, air is removed creating a vacuum. This reduces heat loss by eliminating any kind of conductive and convective heat transfer.

Active Solar Water Heater Systems

 An active solar water heater system uses circulating pumps and controls. Of the active systems, you have direct and indirect circulation systems.

Direct circulation systems are best suited for areas without hard or acidic water and climates without long periods of freezing temperatures. This system works by sending pressurized potable water directly through the collectors. 

Indirect circulation systems, on the other hand, send heat transfer fluids through their collectors. Heat exchangers then transfer heat from the fluids to the potable water. These systems are best used in climates that have long periods of freezing temperatures. Some indirect systems also come with overheat protection. When the solar intensity is too high, this feature prevents the transfer fluid and collector from being damaged.

There are two types of indirect systems: antifreeze and drainback. The antifreeze system uses a glycol-water mixture to transfer heat and protect it from freezing. Drainback systems use pumps to drain the transfer water from the system’s pipes. This ensures that there is no liquid in the pipes for freezing.

Passive Solar Water Heater Systems

With no pumps or wires to contend with, passive solar water heaters are beneficial in their simplicity.

The integral-collector storage system has the storage tanks directly gathering heat by placing them inside the collector behind a glazed side that faces the sun. It is an efficient solar water heater system for households that use water mostly during the day and evening. Families who use more water during the mornings would be better off with a different system.

Thermosyphon systems rely on the natural tendency of warm water to rise to the top. Using thermosyphon can be a feature of several types of solar water heaters. They are particularly effective when used with glycol fluid in freeze-prone climates.

Is A Solar Water Heater a Worthwhile Investment?

There are many ways to cut down on utility costs in a home, with solar water heaters being ideal in warmer climates. Solar water heaters offer a great way to save money by taking advantage of a nearly limitless source of free energy.

 

Source:

https://energy.gov/eere/energybasics/articles/solar-water-heater-basics

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