We collected frequently asked questions about the solar thermal in our FAQ catalog. We devided the questions into different sections: general questions, installation and tubes. We are driven to keep this site up to date at all time. If your specific question couldn't be answered, you can always message us personally via email or give us a call, whatever is more convenient for you. We are happy to assist you in any way.
You can find general questions about our solar plants and AKOTEC products here. Before you buy a solar thermal plant, some questions occur, which have to be answered. Because of that, we have collected those frequently asked questions and answered them beforehand. Nevertheless, we are happy to assist you personally, if you still need our help. If you have questions, which you couldn't find down here, please feel free to contact us at any time. We are happy you are interested in our products.
Please do not hesitate to contact us and fill out the planning sheet. We will forward you to our partners.
We can offer Solar Keymark certificated collectors with 5, 10, 20 and 30 tubes.
A water glycol mixture flows through the collectors and serves as a heat transfer medium. This fluid does not freeze up to a certain temperature.
Our solar fluid VT51 contains corrosion inhibitors, which protect the plant. And because our sealing material is tested with that exact antrifreeze mixture, we guarantee a 20 years manufacturer's warranty when using our solar fluid.
No, it is not possible because the AKOTEC antifreeze fluid is a highly temperature resistant glycol. The entitlement to the warranty would be cancelled when using another fluid.
When operating the collectors with water, the water must be prepared, decalcified and desalinated. Furthermore, a closed circuit must be existent and not an open drain back.
Up to a temperature of -28°C, the heat transfer fluid is liquid. From the freezing point of -35°C, the antifreeze mixture changes to the solid state of aggregation.
The main difference is the tube. As the name suggests, the Direct Flow tube is flowed through directly by the heat transfer medium. Only the manifold of the Heat Pipe, however, is flowed through by the fluid. The tube has its own circuit. The Direct Flow collector has various mounting options: pitched roof, flat roof, facade and balcony, elevation. When mounting, the Heat Pipe mind an angle between 5 °-75 ° and vertical tube position. The collectors must be assembled elevated within that angle or on a pitched roof only.
The collectors produce yields even during the winter time and in diffuse light. This is due to the inner pipe system which is 100 % vacuum isolated. The vacuum tube has no heat loss and does not cool down in contrary to common flat collectors.
An overheating can be avoided through a professional system planning and a sufficiently dimensioned storage tank. We recommend for systems with an irregular heat consumption (regular heat consumption: process heat, pool heating) and especially for private applications the Heat Pipe collectors. They possess an overheating protection, optionally at 100 °C or 160 °C depending on the product version.
Either you choose the Heat Pipe with the automatically shut down function or you have to plan a big dimensioned storage tank for saving the surplus energy.
AKOTEC collectors are hail tested. Please contact your insurance agent.
The collectors reach up to 120 °C under optimum sun radiation.
No, the tubes are coated with a nano powder silicon dioxide and repel dirt.
The vacuum tube collectors produce yields even in diffuse sun light. Yields are generated from a sun radiation of 250 Watt.
AKOTEC collectors suite for upgrading existing heating systems as well as supporting conventional heating systems.
At the zero point, the efficiency factors are almost equally. More important is a height of the efficiency factor at the operating point. At an average temperature of 80 °C the efficiency factor of flat collectors amount 30 %. The AKOTEC full vacuum tube collectors have with 55 % a significantly higher performance. (Get to know more about this topic in our comparison of the efficiency factors!)
No, the copper of the manifold may be damaged by chlorine content and corrodes faster. We recommend the use of swimming pool heat exchangers to prevent corrosion.
Our full vacuum tubes are unique in the market, regarding their system and the way they are manufactured. They are 100% made in Germany and our replacement tubes fit into almost every solar plant from other manufacturers. We have collected the most important facts and information about our tubes, so that you get a perfect first overview. If you have any additional questions, or want to talk about a specific solar plant right away, please feel free to contact us. We are happy to help you!
The tubes with one side coating have a performance of 80 Watt (df) and 75 Watt (hp) (data from Narva). In connection with a reflecting area the double coated tubes can generate up to 110 Watt performance.
As the name suggests, the Direct Flow tube is flowed through directly by the heat transfer medium. Only the manifold of the Heat Pipe, however, is flowed through by the fluid. The tube has its own circuit. The Direct Flow collector is very versatile in relation to its mounting options. Everything is possible – from pitched roof, to flat roof mounting, to facade or balcony mounting up to elevation. Please mind that the Heat Pipe must be elevated between an angle of 5 ° – 75 °. Therefore the collectors can only be assembled elevated in that angle or on a pitched roof. The tubes are available on request in the following lengths: 0,8 m, 1,5 m and 1,75 m. The standard length is 2m.
No, as long as the tube is not damaged it does not lose its vacuum and 25 years of stable energy yields are ensured.
In contrary to standard tubes, power tubes are double coated and used for reflector collectors or if the collector is mounted on a reflecting area such as a bright facade or a tin. It is possible to generate up to 40 % more energy yields by using the reflections of the sunlight.
The absorber plate is made of copper and coated with Titan-Nitrit-Oxyd. In fact there are multiple layers. See (TINOX energy Cu): http://www.almecosolar.com/Brochure/tinox_energy_new_de.pdf
This is ensured by the innovative and sturdy NARVA glass-to-metal connection which does not punish the glass through movements. Therefore the glass-to-metal connection resists to powerful axial and transverse forces effortlessly. The NARVA solution is protected by patent law: http://www.narva-solar.de/de/technologie/glas_metall.html
The Sydney tubes have a glass tube as protection of the inner tubing. Therefore the tubing system is in the atmosphere and ages. The Power decreases already after 2 years. The tubing system of the NARVA tube is vacuum isolated. Materials do not age inside of vacuum. This is why our collectors generate stable energy yields over 25 years.
Reflectors are not included in the scope of delivery, because the reflection of a white wall, a glaced tiled roof or a zinc tin roof are enough. The reflector has to be installed on site.
We get a lot of questions regarding the installation of our solar plants. And even though we try to find a solution for every problem, when it comes to the installation, we have to clarify some questions and information beforehand. We have collected every important point and question regarding the installation of our solar plants. If you can't find your question down below, you can send us an email or give us a call. We are happy to assist you any time!
No, the Heat Pipe collector needs to be assembled between an angle of 5° – 75° and with vertical tubes to ensure that the condensed fluid flows back in the tube. In contrary the Direct Flow collector can be assembled on a flat roof, facade/balcony and elevated. Even the position of the tube is freely selectable.
The Direct Flow collectors are perfectly suitable for balcony and facade mounting because they can be assembled flat on a wall with horizontal tubes. The Heat Pipe collectors can be assembled on a facade/balcony too, but they have to be elevated to an angle between 5° – 75° with vertical tubes.
The flow works despite horizontal mounting because the fluid is pumped through the collector with a pump.
This depends on the flushing and filling pump. We recommend a flushing time of 30 – 45 minutes in a single-family house.
In theory it is sufficient, but on construction site it must be planned 10 ° because the tolerances are larger and with that the 5 ° can be fulfilled.
Direct flow system: It is particularly important to empty the whole system because the tube is tethered wet. Afterwards take off the housing cover and remove the spring clips. Now you can dismount the tube easily. Heat pipe system: Remove the housing and pull the tube 10 cm back. Take out the tube backwards. It is not necessary to empty the system, because the tube is dry tethered.
From the heat generator the flow is always hotter side and the return the colder side. The collector is the heat generator in a solar system. The installation of flow and return is freely selectable.
It consists of a white coated plastic aluminium plate.
The Direct Flow collector is mountable on a flat roof, facade, balcony and elevated. Even the position of the tube is freely selectable.
We recommend the use of Solar-Fermit with hemp to seal the fittings properly. Teflon tape is not suitable, because of the high thermal load.
Yes, we can offer an in-roof solution for our collectors, that are mounted like a roof window.
Please mind a minimum distance of 1m (100cm).
The collector can be perfused with a maximum pressure of 10 Bar.
The sensor must be mounted at the flow.
We recommend the facade mounting.
It is not necessary to mount the air vent on the highest point of the system when the system is filled with a filling pump. The filling pump flushes air inclusions out of the system. We recommend installing air vents on large systems (more than 15 KW/120 tubes). The solar fluid gases a bit out on heating because it can absorb less air in hot state than in a cold state. The air vent is used as an air buffer container and the solar fluid includes the air again in cold state. The air vent must not be provided with automatical air vents.
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Gefördert durch das Ministerium für Wirtschaft, Arbeit und Energie aus Mitteln des Europäisches Sozialfonds und des Landes Brandenburg. Mehr erfahren
Funded by the Ministry for Economic Affairs, Labor and Energy with funds from the European Social Fund and the State of Brandenburg. Read more