Collectors solar thermal collectors are classified as low, medium and high temperature depending on the way you work.
- Low-temperature collectors. Provide useful heat at temperatures below 65 ° C.
- Collectors medium heat. Are devices that concentrate solar radiation to deliver useful heat at a higher temperature, usually between 100 and 300 ° C.
- Manifolds high temperature. They are working at temperatures above 500 ° C. They are used for power generation.
Systems that make up a solar thermal system
The basic outline of a solar thermal installation is as follows:
A solar thermal system consists of various systems
System capture solar radiation
The system for capturing solar radiation consists of solar collectors connected together. Its mission is to capture solar energy for conversion into thermal energy, raising the temperature of fluid flowing through the system.
Among the various solar collection systems include:
- Solar collector plane. It is the most widespread solar collector, you can get increases of 60 ° C at a reduced cost. It is used in solar thermal plants low temperature.
- Unglazed solar thermal collectors. It is common, for example, to heat swimming pool water. The temperature rise is low, around 30 ° C. They are cheaper than flat solar collectors.
- Vacuum solar collectors. They consist of metal tubes lining the metal tube containing the working fluid leaving between them a chamber which acts as an insulator. They have a very high performance, but its cost is also high.
- Solar collectors systems concentration of radiation. They are used for installations that require higher temperatures. Panels are used in semi-parabolic shapes or cylindrical.
- Thermal solar collectors systems for monitoring the position of the sun. His position is changing in throughout the day to maintain a position perpendicular to the solar radiation received.
System accumulation of thermal energy
it is to store energy in a heat storage tank for later use. The hot water obtained by the feedback system, is carried to the site where it is to use. It can be directly, as in the case of heating pool water. In applications of domestic hot water or heating demand does not always coincide with the time when there is enough radiation, so if you want to maximize daylight hours will be necessary to accumulate the thermal energy at the time of day when this is possible and use it when there is demand.
The system thermal energy storage consists of one or more hot water tanks. The size of the storage tanks must be proportional to the estimated consumption and should meet the demand for hot water from one or two days.
distribution system thermal energy
In this system all elements for distribution of heat transfer medium and conditioning consumption are included: control, pipes and conduits, expansion tanks, pumps, strainers, valves, etc. Also part of the system support system based on conventional energy sources (electric, oil or gas boiler), necessary to prevent possible errors arising from the absence of solar radiation and deal with peaks in demand.
support conventional energy systems
The solar thermal energy need conventional support systems in anticipation of the lack of sunlight or a higher dimensioned (oil, gas or electricity) consumption. In most cases both installations in houses, and buildings, solar installations are designed to provide housing 60-80% of respondent hot water, though in areas with high insolation over year, the percentage of contribution is usually higher.
In the lower radiation months (January, February, November and December) reaches not cover 60% of energy needs, while in the summer months virtually 100% of them is reached. Thus, the goal that solar thermal systems are designed is to cover at least 60% of the annual energy needs depending on your geographic location.
Pretender cover above 60% or 70% annual solar thermal energy required to place a large solar field, and it would be a very high cost that would not ever repay, in addition to causing the months of higher radiation solar, such as summer, a production surplus that could not be used and would cause overheating problems throughout the facility.
Therefore the facilities that work best and are pay for themselves before they need hot water for the whole year, heating (underfloor best) for winter and summer have pool or even the whole year.
Economic and social aspects of a solar installation
The initial investment of a solar thermal system will be higher compared to conventional energy supply system. Moreover, the cost of operation for more than 25 years of life of the solar installation will be irrelevant compared to the purchase of fuel or electricity, repairs, maintenance, etc. associated with the conventional energy system.
The installation of solar thermal energy is economically more advantageous economically, since all the energy we get from the sun with solar thermal collectors, will spare us the energy to produce (burning fuel in a boiler) or consume (network Electrical distribution). A solar thermal installation rentabilizándose just over the years, since the energy savings resulting in cost savings materialize, which allows end amortizing the cost of installation. This amortization can vary between 5 and 12 years depending on the size of the installation of repayable grants obtained, the place where it is installed (more or less solar radiation) and the smaller user or greater needs.
In the case of placing these solar thermal systems in new housing construction or rehabilitation, amortization can be considered instantaneous, since the increase represents in the total price of housing is very small; the amount you pay for the higher cost in each year mortgage loan is less than the amount in euros which involves the least expenditure of gas or oil.
Highlight the main advantages of a solar thermal system we
- Economic benefits, same needs as for a conventional system will require less fuel consumption, which represent user a lower annual expenditure. Moreover, solar energy is independent of conventional fuel and supply, since it is compatible with any conventional system and independent variation of the purchase price of fuel.
- Environmental benefits, since the conventional power generation systems has very important environmental costs (CO2 emissions, climate change, waste, nuclear waste, acid rain, etc.) in connection with solar systems. On average, one m2 of solar thermal collector is able to avoid annually the emission into the atmosphere of a tonne of CO2.
- Easy maintenance. The lifetime of solar thermal systems is above 25 years and the maintenance required, although necessary, is very minor in the case of conventional systems.
However, the installation of thermal systems presents a drawback: the installation of the conventional system that would result if the solar collectors are not from installing, and sometimes problematic installation in existing buildings as a result of their lack of foresight is required project level.
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Last review: June 2, 2015