What are the components of a solar panel? This article is dedicated to explaining what these parts of the solar panel are.
Some time ago we published an entry in which we talked about the different types of solar panels, focusing on installations that used low temperature solar panels. Well today we are going to tell you which are the main elements of flat plate solar collectors , which are the majority low temperature panels in the market.
What are the components of a solar panel?
These types of panels are mainly used to heat water for sanitary use (DHW) . However, even being the simplest equipment, to make a good choice it is essential to know the characteristics of the elements that constitute it.
This information is useful to be able to evaluate the quality of the collectors and choose the most suitable one based on the weather conditions to which it will be subjected; the purpose of the installation; and the budget available.
Components of a solar panel
The 4 elements that we must look at are: the transparent cover, the collector plate, the insulator and the casing.
It is responsible for producing the greenhouse effect , reducing convection losses and ensuring the collector’s tightness to water and air in conjunction with the casing and joints.
The greenhouse effect achieved by the cover consists in that the radiation that has passed through the cover and reaches the collector plate, a part is reflected towards the transparent cover with a wavelength for which it is opaque, with which it is possible to retain radiation inside. This effect defines the characteristics of the roof:
- High transmission coefficient of solar radiation in the range of 0.3 to 3 mm, which must be preserved over the years.
- Low transmission coefficient for long waves, greater than 3m.
- Low coefficient of thermal conductivity, which makes it difficult for heat to pass from the interior surface to the exterior, thus minimizing losses.
Its mission is to absorb solar radiation as efficiently as possible and transform it into usable thermal energy by transferring it to the heat transfer fluid.
The face of the collector plate that is exposed to the sun must be protected from the sun’s rays by means of:
- Black or dark colored paint that absorbs solar radiation. It has the drawback of having an emission coefficient substantially equal to the absorption coefficient, so it is not recommended for high temperatures.
- selective surfaces. It has a high solar radiation absorption coefficient and a low emission coefficient. There are no simple materials that have this property, so it is achieved by layering or special surface treatments.
The collector plate is protected on its back and sides by means of insulation to prevent thermal losses to the outside.
The characteristics of these insulators must be:
- Resist high temperatures without deteriorating, which is often achieved by placing a reflective layer between the plate and the insulator, which prevents the insulator from directly receiving radiation.
- Give off few vapors when decomposed by heat and if it happens that they do not adhere to the cover.
- Do not degrade due to aging or other phenomenon at the usual working temperature.
- Withstand the humidity that may occur inside the panels without losing their qualities.
The most used materials are fiberglass, rigid polyurethane foam and expanded polystyrene. Whatever the material chosen, it must have a coefficient of expansion compatible with that of the other components of the solar panel.
It is responsible for protecting and supporting the elements that make up the solar collector, in addition to serving as a link with the building through the supports.
You must meet the following requirements:
- Rigidity and structural strength that ensure stability. It is of the utmost importance since it must resist the pressure of the wind.
- Resistance of the fixing elements: mechanical for the forces to be transmitted; and chemical to resist corrosion.
- Resistance to weathering, to the corrosive effects of the atmosphere and to chemical instability due to inclement weather.
- Ventilation inside the collector to prevent water condensation inside the collector.
What are the components of a solar panel? Basically the parts are those exposed above.