Solar water heater system (solar collectors)

- Solar water heating systems include storage tanks and solar collectors.
- There are two types of solar water heating systems: Active, which have circulating pump and controls, and Passive, which don’t.
- Most solar water heaters require a well‐insulated storage tank.
- Solar storage tanks have an additional outlet and inlet connected to and from the solar collector.
- In two‐tank systems, the solar water heater preheats water before it enters the conventional water heater.
- In one‐tank systems, the back‐up heater is combined with the solar storage in one tank.

  • Solar Collectors

Four types of solar collectors are used for residential applications:
Flat‐plate collector

Integral collector‐storage systems

Batch system

Evacuated‐tube solar collectors

Flat‐Plate Collector
Flat plate collectors are designed to heat water to medium temperatures (approximately 140 degrees Fahrenheit).
solar water heater system- solar collector
Flat plate collectors typically include the following components:
1.Enclosure: A box or frame that holds all the components together.
2.Glazing: A transparent cover over the enclosure that allows the sun’s rays to pass through to the absorber. Most glazing is glass but some designs use clear plastic.
3.Glazing Frame: Attaches the glazing to the enclosure. Glazing gaskets prevent leakage around the glazing frame and allow for contraction and expansion.
4.Insulation: Material between the absorber and the surfaces it touches that blocks heat loss by conduction thereby reducing the heat loss from the collector enclosure.
5.Absorber: A flat, usually metal surface inside the enclosure that, because of its physical properties, can absorb and transfer high levels of solar energy.
6.Flow Tubes: Highly conductive metal tubes across the absorber through which fluid flows, transferring heat from the absorber to the fluid.

Integral Collector Storage (ICS) Systems
In other solar water heating systems the collector and storage tank are separate components. In an integral collector storage (ICS) system, both collection and solar storage are combined within a single unit. Most ICS systems store potable water inside several tanks within the collector unit. The entire unit is exposed to solar energy throughout the day. The resulting water is drawn off either directly to the service location or as replacement hot water to an auxiliary storage tank as water is drawn for use.
solar water heater system- solar collector- solar city

Batch System
solar water heater system- solar collector- solar - city

The simplest of all solar water heating systems is a batch system.
It is simply one or several storage tanks coated with black, solar-absorbing material in an enclosure with glazing across the top and insulation around the other sides.
It is the simplest solar system to make. When exposed to sun during the day, the tank transfers the heat it absorbs to the water it holds.
The heated water can be drawn directly from the tank or it can replace hot water that is drawn from an interior tank inside the building.

Evacuated Tube Solar Collectors
This type of system features parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin’s coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for commercial applications.
solar water heater system- solar collector- solar-city
solar water heater system- solar collector- solar  city

Evacuated-tube collectors generally have a smaller solar collecting surface because this surface must be encased by an evacuated glass tube. They are designed to deliver higher temperatures (approximately 300 degrees Fahrenheit). The tubes themselves comprise the following elements:

1.Highly tempered glass vacuum tubes, which function as both glazing and insulation.

2.An absorber surface inside the vacuum tube. The absorber is surrounded by a vacuum that greatly reduces the heat loss.

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