The solar panel or solar collector is the part of the plant directly exposed to solar radiation, to which is entrusted with the energy conversion. Technological research has led to the development of various types of collectors (suitable for solar thermal or solar photovoltaic), characterized by high performance and different operating conditions:
Solar panels glazed non-selective - collectors of the first generation, consisting of a bedroom isolated from a sealed chamber formed between a tempered glass directly move to the sun and a rear shell insulated. Within the solar panel is inserted a metallic absorber blackened, so as to increase efficiency. This type of solar panel is the cheapest and most widely used for the facilities used to cover the annual domestic needs, especially in geographic areas where there is plenty of direct radiation in the winter months and fairly mild weather conditions.
Solar panels glazed selective - represent the evolution of traditional panels to which is added a treatment of the surface of the absorber, in order to improve its efficiency. The cost of these panels is obviously higher but provide yields of 10% higher compared to the traditional panel, thanks to a performance improvement in the winter months.
Vacuum solar panels - are composed of an array of glass vacuum tubes, each containing an absorber (usually a metal plate black) that captures solar energy and transfers it to a fluid that transports heat. Thanks to the insulating properties of the empty space, the heat losses are very low and can reach temperatures of about 100 ° C above the temperature of the environment. Therefore, these panels are particularly suitable for use at higher temperatures, or for low ambient temperatures (winter). The cost is significantly high and may ò exceed 150% of the purchase of the flat-plate collectors.
Solar panels glazed hemispherical - are manifolds new generation having components similar to those of the collectors glazed flat but configured and optimized to compose a final configuration hemispherical. This configuration allows to obtain, with the same base area of the collector, a capture surface exposed and productivity levels significantly higher than the average plane models.
Solar panels glazed with hot air
Circulates air instead of water. The air is circulated between the glass and absorber or, in some cases, in an interspace formed between the absorber and the bottom of polyurethane insulation.
Particularly suitable for the heating of buildings or dry food.
Are devoid of glass and the water passes directly inside the tubes of the panel where it is heated by the solar rays and is ready to be used. The limit of these panels is that, not being insulated, work with an ambient temperature of at least 20 ° C (below the balance between energy accumulated and scattered energy is unfavorable), and the maximum temperature of the water does not exceed 40 ° C. Precisely for this reason their use is ideal for seasonal users.
Their cost is significantly lower than the glass panels and the installation is so simple that it can be done independently.
The material used to build the panels can be discovered PVC, Neoprene or polypropylene. This material allows you to create panels capable of withstanding water pressure up to 6 atmospheres.
Concentrating solar collectors
The collectors concentrating solar collectors are concave designed to optimize the concentration of solar energy in a particular place (fire). They are effective only with direct sunlight as they have to follow the movement of the sun.
Panels with integrated reservoir
In the panels with integrated tank the heat absorber and the storage tank are a single object and take you directly to the solar energy to heat the water accumulated. To effect the principle that the hot water tends to rise and cold to descend is created inside the tank so a so-called convective motion which distributes the heat captured in the whole mass of water. Comfortable, compact formed from a single block, are easy to transport and equally easy installation. Some of them are not suitable for use in places where the winter is long and hard because their performance at that time is scarce and because the water in the tank may freeze and damage the panel. They are still available on the market also compact systems suitable for all weather conditions.
Translated via software
Italian version of ReteArchitetti.it