General built-up of the solar collector systems

In Hungary – thanks to its relatively good climate conditions – mostly the liquid medium is used in solar collectors for utilizing the solar energy.

These solar collectors producing heat are mostly consisting of the following elements:

·         Solar collectors, which absorb and transmit the transformed heat, coming from the solar energy, to the liquid medium.

·         Containers, which store the heat produced by the solar collector in the form of warm water.

·         Operator, regulator, and safety, controlling appliances. Here belongs the circulating pump, the automation, the expansion reservoir, the safety valve, the pressure- and thermometers, the control and switch valves, and other appliances.

·         Piping, which connects the collectors with the reservoir and the user. 

The solar collector systems depending on the liquid used in the system can be one or two circled.

·         In the case of one-circled system the heated liquid which circles in the collector is the water for direct use itself. The advantage of this system is the simplicity, the disadvantage is that it must be used when there is no freezing outside. It is also a problem that lime-scale is produced while used or there is a hazard of the water boiling.

·         In the case of two-circled system the collector circle (primer) is a separate closed circle, which is filled up with antifreeze liquid. The antifreeze warned up in the collector warms up the water in the reservoir with the help of a proper heat panel. Technically it is possible to omit the antifreeze liquid, and use water, which enables better heat exchange, but a smaller reservoir and a small automatics is needed in this case.

The double circle systems can be used safely all year round, their advantage is the higher yearly yield, the safe use, by eliminating the lime-scale, though their disadvantage is the higher costs due to the heat panel, and also the more complicated operation. 

 Where:

1.    Heat producing (solar collector)

2.    Control, operator devices

3.    Cold water network

4.    Heat storage (warm water reservoir)

5.    Heat usage (warm water network)

Based on the liquid work medium, the solar collector systems can be grouped into gravitational or pump operated circulation systems.

·         In the case of gravitational circulation system (based on specific gravity variance) the reservoir is placed above the collectors, where the circulation of the heat transmitting work medium, thanks to the solar energy, is a result of the specific gravity variance of the heated liquid. The advantage of these systems is their simplicity, the omitting of the circulation pump and the automation, their disadvantage is the fix position of the reservoir. In the case of gravitational systems, the pressure difference of the circulation system is relatively small, therefore only small flaw resistance collectors, pipes and reservoirs can be used.

·         In the case of pump operated circulation systems the heat transmitting liquid is flowed by a pump. The advantage of the pump-operated systems is, that the reservoir can be placed anywhere, an extensive system can be built, it is not necessary to use small flaw resistance units, and with the switch-on, switch-off the pump, or by changing the RPM (revolution per minute), a well controlled operation can be realized. Their disadvantage is the higher investment, and operation cost.