Co-finanziato
Dal Programma LLP dell’Unione Europea
Comenius work group by Maria Casano, Cecilia Del Ministro, Valentina
Lucarelli, Melania Gambino, Elena Maggio
3 Types of solar pannels
There are three types of solar panels: uncovered, vacuum and glazed. The uncovered panels are
made of black polypropylene tubes, neoprene, pvc or metal through which circulates the water.
There is no solitary confinement temperatures are limited to about 20C. These panels are ideal for
use where low temperatures are required, for example summer warming of swimming pools. The
glass panels are the most commonly used solar panels; these panels are made of a flat insulated
box with a plastic or transparent glass side. The box contains a flat black plate that absorbs solar
energy that is transmitted to the fluid that transports heat. The glass above and below the
insulation reduces heat loss. These types of panels produce heated water up to 70 degrees
centigrade. Vacuum panels are composed of an array of vacuum glass tubes, each of these tubes
contains an absorber that captures solar energy and moves it to a fluid that carries the heat. Heat
losses are very low and you can reach temperatures up to 100 degrees Celsius.
Natural circulation
The sun rays heat the solar liquid (water + antifreeze) which is found in the pipes inside the
thermal collector. The liquid rises naturally to the top of the tank which is positioned horizontally
above the panels. Here the liquid transfers its heat to the water inside the tank. The water, which is
heated by the sun, then goes into the houses’ hydraulic system.
Forced circulation
The forced circulation system is necessary when the boiler is lower than the solar collectors.
Inside the thermal collectors are tubes and inside the tubes flows a liquid (water + antifreeze)
which heats up when it is exposed to the sun. A control unit measures the temperature of the
liquid in the panel and also measures the water temperature inside the tank. If the liquid in the
panels is hotter than the water inside the tank, the control unit activates a pump which sends the
liquid into the circuit by passing through a coil inside the tank. The exchange of heat from the liquid
to the tank’s water takes place via the coil . The heat then enters the house’s water circuit .
Solar panels can produce thermal energy even if it isn’t sunny
Solar panels can produce thermal energy even if it isn’t sunny, in fact the radiation incident on a
panel isn't given only by sunlight but also by the radiations present in the entire sky. Obviously, if
it’s sunny, solar panels work at their best. Besides to have hot water always and regardless the
weather, it is necessary to use integrative solutions of solar radiation. If in the house there is
already a flash boiler gas with electronic control for the production of domestic hot water, it is
possible to connect the existing solar thermal plant. The solar system must integrate the traditional
production of hot water, allowing a considerable saving of energy. If you cannot connect to the gas
boiler, you must insert in the tank an electrical resistance of at least 1 kW with thermostat set at
about 40 ° C. All solar systems compact in trade are equipped with an electrical heater positioned
inside the tank.
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