THE SITUATION IN SPAIN
Within the present tendency to advance in the use of the renewable energies, the thermal solar energy and its use in the hot water generation in unifamiliares facilities as much collective - such as blocks of houses, residences of the third age, polideportivos, campings, hotels, etc. -, it is one of the practical applications that they will be able to be used within the urban frame to reduce the polluting gas discharge and foreseeably more to diminish the dependency of fossil fuels.
The new legal frame that is being developed in Spain foments and even it forces to use devices that guarantee a minimum of cover of power demand by means of the solar energy. In addition, subventions exist from different estates from the Administrations.
HOW IT WORKS
A thermal solar power plant concentrates the heat of the accumulated Sun in denominated panels collectors and it transmits it, either to the running water who we used in our houses to shower to us, to mop, etc., or to the used fluid to heat by means of radiators or radiating ground. It is therefore, a talent that concentrates and transmits the solar heat from a site to another one, without producing electricity in no opposite case that the photovoltaic plates, that yes generate current electrical.
||Scheme of hot water generation by means of thermal Solar System.
The water can be used so much in a building to unifamiliar as in a block of buildings
The collectors absorb this heat and they concentrate thanks to the effect conservatory created inside the panel, the isolation of the average outside, and the capacity of absorption of the bodies, - fomented by the chemical treatment which he is put under certain parts of the panel. Inside the collectors primary circuit exists a closed circuit - by which a fluid with antifreeze runs. This liquid reaches temperatures superior to 100º C in the plates with selective covering, that are the type that we used, and it is made circulate, in circuit always closed, until the interior of a called cistern accumulating, where the tube acquires coil form and enters direct bonding with the water that we will use later in our house - secondary circuit -.
The heat of the fluid that crosses the coil transmits to the water destined to the consumption that surrounds it, increasing its temperature. In case of necessity, for example dimmed days, use is made of a generating equipment help, generally a gas boiler or gasohol, to elevate the temperature the degrees that are necessary. According to the present norm, the water must leave the storage cell to a temperature of 60ºC, to avoid danger of legionella, although later it is mixed with cold water to reduce the temperature until 45ºC., that is the conventional temperature of consumption.
All this process is controlled by a central electronics that is the one that is in charge to automate and to coordinate the circulation of the water of the primary circuit when greater thermal contribution is necessary, to control the temperature of the collectors, to guarantee the security of the system, and even in more advanced models, to send an electronic mail warning of incidences.
ELEMENTS OF THE INSTALLATION
Panels, modules, collectors, solar panels
Water storage cell
All these words usually are used like synonymous, although to the panels that are used in thermal calls to them by convention ' solar collector '. They are located commonly in the tile roof and they serve to absorver the heat produced by solar rays.
Deposit where the water is accumulated that later is destined to the domestic consumption, either for faucets and shower, or for the system of heating. The storage cell usually is also heating, since the system that accumulates the water finds in its interior.
The hot water storage cells are a key element in the installation, since they allow to store the water warmed up during the day to be consumed when it agrees. Thanks to them can be had hot water during 24h of the day, and for that reason they must be very well isolated.
A storage cell is formed by a deposit with a coil in the interior, around which the hot fluid circulates that comes from the solar receivers and whom the heat to the water yields that surrounds it, and perfectly isolated with foam polystyrene lasts and .
Another conformation of the storage cells is the surrounding double, a deposit within another one. In the interior the water lodges to warm up and around the outside the hot fluid coming from the solar receivers circulates. From this form a greater faying surface is obtained.
The storage cells allow to perfectly integrate the thermal solar energy to a system of heating to gas or diesel oil, being the element in which the power contributions of the receivers and the boiler come together.
For it storage cells with double coil are used, inferior for the liquid coming from the solar receivers (to the smaller temperature) and superior one for water coming from the boiler (to greater temperature); or storage cells of surrounding double stratified, where the outer deposit is divided by zones to different temperature, the inferior one to pave thermal and the superior one for the boiler.
All sistems of thermal solar energy needs an auxiliary equipment that provides the necessary power when the Sun does not reach to cover the demand. Boilers of gas or gasohol of high performance usually are used.
System that warms up the water that is consumed later. Normally the tank or storage cell is within that contains the water.
Solar collectors of low temperature
They reach up to 70ºC of temperature; are used in hot water production or heating.
Percentage of power consumption covered by the solar energy.
It is the device by which the heat generated in the collectors is transmitted towards the water which later we are going to use. In thermal Solar System, usually it is a tube with coil form, - located within the accumulating or heating tank -, through as the originating hot water of the collectors runs. The water to consume makes contact with enemy with that coil and receives the heat.
Hydraulic circuit that consists of hydraulic pump, different types from valves and tubes. Two different circuits exist generally: primary, which he is that by which circulates the fluid that is warmed up within the collectors, and the secondary one, that is the formed one by the consumption water.
System that controls the temperature and the correct operation of the installation. It can get to even reach a high degree of sofiscicación, arriving to send electronic mails to the pertinent direction in case of failure.