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18.06.10
Donauer Solartechnik presents new Off Grid brochure
The growth of the population and the economy leads to an increased demand for energy in many regions of the world. Many networks and power plants are ...
16.06.10
Donauer Solartechnik introduced a number of innovations at Intersolar Europe 2010.
Employees provided information on the company’s innovations to hundreds of customers and attendees at the nearly 400-m² booth.
Frequently asked questions and answers concerning solar technology
What is solar heat?
Technology that permits water to be heated by solar energy is usually referred to as solar heat. The technical term is called solar thermal energy (Greek: thermie = heat). However, solar thermal energy can also be used to produce hot air and even cold air.
How is a solar thermal system built?
Solar heating systems usually consist of a solar collector, a control unit equipped with a pump and a well-insulated hot water storage tank. Specially coated absorber sheet metal collects the solar energy in the collector (Latin: collector = accumulator) Copper pipes, through which a heat transfer fluid flows, are fixed beneath the sheets. The control unit equipped with the pump transports the heat. The heat stored in well-insulated solar storage tanks is then released into the storage tank water by heat exchangers. Thus the hot water is also available at night or on rainy days.
What kind of different types of collectors are there?
The most common collector is the flat-plate collector. Its core is the absorber (coated aluminum or copper plating and tubing). It has a front cover made of safety glass and temperature resistant insulation on the side and rear. These components are held together by a stable frame.
There are evacuated tube collectors next to it. The absorber sheet metal runs through glass tubes in which there is a vacuum. The vacuum keeps the heat losses of the tube collector lower than with flat-plate collectors and it is thus particularly effective during the cold second half of the year.
In addition to these glazed collectors, there are also swimming pool absorbers. They are usually made of black plastic hoses (absorber mats) and are used for public or private swimming pools. They are inexpensive to purchase and already pay themselves off after a few years.
Has solar thermal technology been fully developed?
Yes. The components for domestic water heating, backup heating and swimming pool heating as well as for power generation have been technically mature for years. They have a reached a high level of performance and have a service life of 10 years.
Can I also use a solar thermal system for heating purposes?
More and more Germans are also using solar thermal energy to heat within their own four walls.
Combined solar energy systems for domestic water heating and backup heating can supply a house with heat during spring and fall and support the boiler in the winter.
Solar thermal systems for backup heating have a larger collector surface than systems that are only used for domestic water heating. They also have a special storage tank.
Solar systems are particularly efficient when used for backup heating in homes that are equipped with modern heating systems and good heat insulation.
How is the solar heating system protected against frost and how long is its service life?
The heat transfer fluid that is located in the collector and in the tubes up to the storage tank (solar circuit) is a mixture of water and anti-freeze.
The glycol used does not pose any risks to consumer health and protects the system, even during severe frost. Today, the service life of a solar heating system is over 20 years.
Is my home suitable for solar thermal system?
Regardless of whether photovoltaics or solar thermal energy, almost every home is suitable for using a solar power system.
The right alternative for your home is surely among the numerous options available for installing a solar power system. You can cover a portion of the required investment costs through the corresponding subsidy programs.
Depending on the existing building requirements, there is a wide variety of methods for installing solar power systems. In addition to solar power systems that are directly integrated into an existing building, there are also systems that can be installed independently of buildings.
A distinction is made between:
- On-roof installations: Mounting the collectors on mounting frames above the existing roof covering
- Roof-integrated installations: Mounting the collectors in place of the roof covering
- Flat roof installations: Mounting the collectors on flat roof mounting frames
- Ground-mounting in outdoor areas
- Façade integration
- Fixed system on a tower
It is important that the planned surface is largely free of shade. In addition, the roofs structure must be capable of supporting additional loads and the modification measures should not adversely affect the overall appearance.
How expensive is a solar thermal system?
The price for a system for a 4-person household is between 4,000 and 8,000 euros. If you would also like backup heating, the price is approximately between 8,000 and 11,000 euros. Systems equipped with evacuated tube collectors are somewhat more expensive than systems equipped with flat-plate collectors. The prices apply to all required components including assembly and value-added tax. Possible subsidies are not taken into consideration here.
For domestic water heating systems, you can calculate a collector surface between 1.0 and 1.5m² for each person. The same energy yield can be achieved on the west and east side with a slightly larger collector surface. Flat roofs equipped with a free-standing system are also particularly suitable. Systems can also be installed in gardens or mounted on a wall.
The required hot water storage tank requires a space of approximately one square meter and approximately two meters in height.
When should a solar thermal system be installed?
The time for installing a system is particularly favorable when building a new house. In general, approximately 20% of the costs can be saved compared to subsequent installation.
Whoever does not have the financial leeway should always ensure inexpensive subsequent retrofitting options by installing the adequate piping and a suitable hot water storage tank.
Generally, buildings can always be retrofitted. Retrofitting existing buildings is particularly favorable when modernizing heating systems or renovating roofs. Additional funding is available to those who modernize their heating system or enhance their thermal insulation and install a solar power system at the same time. Expert specialized companies should be consulted for this.
How high are the operating and maintenance costs?
The electronic components (pumps, controllers) in a solar thermal system require electricity. The costs for the electricity do not exceed 15 euros per year. Maintaining the solar thermal system at regular intervals ensures a long service life and costs approximately 100 euros. Unlike heating systems, solar thermal systems only require maintenance every two to three years.
What are the advantages of solar thermal energy?
- The sun is the greatest and safest source of energy. It is guaranteed to be available for billions of years to come.
- Solar energy is clean and free energy which allows you to enjoy good long showers without any regret.
- Solar energy is used directly on site. There are no transportation costs.
- The resources for setting up a solar thermal system are generated in two years. Thereafter, it provides a pure energy gain.
- Solar thermal systems are technically mature, have a long service life and increase a buildings value.
- Solar thermal systems increase the quality of life and provide added creature comforts.