System

System Characteristics

Recommended Regions

Advantages

Disadvantages

Open-Loop

It consists of a single tank wherein the same liquid that runs through the collector is stored and circulated.

System is used in Mediterranean climates where freezing is an unexpected occasion or  at other regions, only during milder seasons.

Since the water is heated directly, in comparison to the closed-loop systems, it works more efficiently early in the morning. It is less costly than a closed-loop system.

Even  a light freeze can damage the system.  In regions where freezing is a concern, the system has to be emptied during winter time. It is less resistant to corrosion than a closed-loop system.

Closed-Loop 

A heat transfer liquid runs between the solar  panels  and a jacket  type heat exchanger that surrounds the hot water tank thereby transferring  its heat.

Used in regions that have a harsh winter or with water with high chlorine content.

Anti-freezer which is added inside the heat transfer liquid enables systems to work year-round. It is more resistant to corrosion and it has a higher life.

Its efficiency is lower until the jacket heats itself. (early in the morning). It requires regular checking of the anti-freezer amount inside the jacket.

Atmospheric

It consists of two tanks one on top of the other. The cold water tank on the top fills the hot water tank underneath as hot water is consumed.

It is very useful in areas where water shortage is widespread.

Cold water tank can also be used as a separate water storage tank.

Due to pressure difference between hot & cold water it may cause burns.  Tanks must be placed one on top of the other. It does not look aesthetic on the roofs.

Pressurized

There is no additional cold water tank .   Water is supplied straight from the mains. Collector and the tank is manufactured to resist the pressure.

The units do not necessarily have to be put on the roof. It may be used on the garage, garden or any other location so long as the water tank stands over the panels.

Since the water stored inside the tank is always under public system pressure, cold and hot water run with the same pressure from the taps. It ensures a more pleasurable use.

Since the tank is manufactured from thicker material, it is heavier and   it cost more compared with atmospheric systems.

Systems with Pumps

Water that is heated inside the collector is pumped to the hot water tank by means of an automatic temperature controlling pump. System works by the pump’s power.

It is good for use in multiple (industrial) solar thermal applications or to be used in apartments or villas together when a second heating method is applicable (gas heating)  by means of boilers with double-heat exchangers.

In hotels, industrial facilities or residences it allows the placement of (also large capacity tanks) tanks & panels at wherever needed. It is therefore   more aesthetic. Since the flow-rate can be managed by a pump the efficiency is higher.

It requires more maintenance when compared with systems that work by natural-flow.