Natural circulation solar panel

Solar thermal system: what it is


The solar thermal panel has the capacity of to commute solar radiation into thermal energy getting so domestic hot water that comes transferred e accumulated for later use.

Solar thermal systems, in addition to the production of hot water to be used in the kitchen, bathroom or for the operation of washing machines, are conceived also for to integrate heating systems already present in the building.


The thermal panels they make up a perfect solution foroptimization of the energies inside the house, lowering the costs in the bill greatly.

Furthermore, the installation of a solar thermal system leads to a elevation of the value of the building, with low environmental impact.

Solar panel operation


How does a solar panel work?

The solar thermal system, as anticipated, by i sunrays transforms the energy of the sun in thermal energywithout producing harmful emissions.

Is composed by solar collectorstorage tank, integration generator e control unitall elements connected to each other to ensure correct operation of the system.

Solar thermal system operation
Through panelthe sunlight reaches the absorber, which, warming up will transmit heat to the heat transfer fluid (water + antifreeze). The latter will in turn transfer the water that can be to the users exploited as water for the heating system and domestic hot water.

Based on the way the heat transfer fluid circulates in the coil, there are two types of solar panel:

  • solar thermal forced circulation;
  • solar thermal natural circulation.


In this article there we will dwell on solar thermal with natural circulation.

Natural circulation solar thermal panel


The natural circulation solar panel consists of flat panels on which the reservoir of accumulation double layer.

The heat transfer fluid, consisting of glycolit circulates naturally: water does heats up in the collectors, expands e lightensthen go back in the tank (boiler) e surrender heat to the fluid at a lower temperature.

The water, having given off heat, cools down e weighs down, walking down again in the panel, for create a new cycle.
This system is very economical and simple and does not require electric power units or pumps.

It is used particularly in mild climate regions, as it has lower thermal insulation than a forced circulation system.

Characteristics of the natural circulation panel


The plants are of small size in monobloc, made with both flat glazed and vacuum panels. Yes they can to install on terraces, roofs and gardens and require little maintenance.

Most solar panel systems are a closed circuit, in which the fluid circulates to a limited extent between the collector and the boiler. The benefit lies in the fact that with the closed circuit it is possible to use anticorrosive and antifreeze fluids.

Solar panel for buildings
The coverage of the domestic hot water requirement that solar thermal ensures is 70-80% while the remainder must be produced using conventional technologies.

Ideal for domestic use, with hot water consumption of about 3000 liters per day, the system can dispose of an auxiliary heat generatorable to work in case the water temperature is not high enough.

It is also advisable to equip the boiler with electrical resistance useful for heating water, where a secondary generator cannot be counted on.

Types of solar thermal systems


Il solar thermal with natural circulation consists of three essential elements:

  • Safety valve;
  • Storage tank;
  • Solar Panel.


Le plant configurations they are of two types:

  • solar thermal boiler integration;
  • without boiler integration.


In the first case the reservoir is connected to a instant boilerwithout accumulation.
If the water that is heated by the panel is warm enoughis transferred directly to users and, through a mixing valvemixed with the cold water present in the water system.


If the water leaving the tank has a lower temperature to that set, a specification diverter valve will transfer it to the instant boiler which will provide for warm it up before sending it to users.


In the second case, one does not have no connection between solar system and boiler: the tank is directly connected to the water distribution system.

IS advisable that it is equipped with electrical resistance to heat the water in case of need.

Solar panel for domestic hot water
Tale resistence it starts when the temperature requested by the user is lower than that inside the tank.

Here too there is one mixing valve. This plant configuration is scarcely usedas the presence of electrical resistance could to reduce the economic benefits of the solar panel.

Pros and cons of natural circulation solar panel


I benefits of a solar system with natural circulation are the following:

  • Reduced maintenance;
  • Savings 60% of the energy needs of domestic hot water;
  • Low cost both for purchase and installation;
  • Absence electricity consumption;
  • Installable on any type of roof (flat or sloping);
  • High resistence to breakdowns.


On the other hand, there are also several disadvantages:

  • Weight is high;
  • It results to be very sensitive to sudden changes in temperature;
  • The thermal dispersion is alta especially in winter;
  • It is aesthetically unpleasant.


As for the maintenanceshould be carried out every year and concerns:

  • Verify security valves;
  • Estate mounting elements;
  • Cleaning glass;
  • Residual fluid;
  • Replacement magnesium anodes.

Natural circulation solar panel


A very product Interesting is the Cordivari solar thermal panel with natural circulation. The system Panarea from Cordivari Srl is used for the production of domestic hot water and consists of a kettle with cavity combined with the flat solar collector.
Cordivari solar panelIl solar collector is characterized by insulation in mineral wool and anodized aluminum frame and features a absorber very selective.
The kettle, on the other hand, is made of carbon steel with electrical integration and insulation in rigid polyurethane foam. Cordivari solar panels for hot water own warranty five years.

Solar panels hot water natural circulation


Ariston solar thermal is also a valid alternative. The company Ariston proposes a system of natural circulation for the production of domestic hot water.
Cairo Thermo ensures high readiness in heating sanitary water, even when the irradiation values ​​are low.

The Ariston solar boiler, dialoguing with other devices, it can handle different types of energy and optimize performance. Made from hail tested glass and available in three different capacities (150 l, 200 l, 300 l), Cairo Thermo represents an optimal choice capable of lasting over time.

All Ariston solar panels have warranty five years.


Source: LAVORINCASA.it by www.lavorincasa.it.

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