The market for photovoltaic plants is booming. Due to the guarantee of virtually unrestricted sunshine, their application especially in the Mediterranean countries pays off. In a patent-pending tracking system for medium to large solar power plants, a multidimensionally moving energy supply system safely guides the solar power lines. Even if they are exposed to extreme conditions of wind and weather, a trouble-free operating period far beyond the feed-in period is guaranteed. The service life expectancy of the plants is far more than 25 years.
"Our product is unique," says graduate engineer (FH) Andreas Fleischmann, Managing Director of the RWenergy GmbH in Schwandorf. "We have a unique selling point in the market for our near-the-ground system for the one-axis tracking of up to 36 kWp installed power per individual plant." The advantages are obvious: Besides its low vulnerability to wind, the low installation height plays an essential role.
"In Spain, now the authorities have learned much from the construction mistakes of the past," reports Andreas Fleischmann. "With regard to the landscape, they have become very sensitive. The obstacles for the approval of building work are always high. We have an edge here because our tracking lies below 2 meters. Till the middle of the year, we alone installed at least 300 plants in Spain. "In the meantime, interest in the patent-pending tracking system 's:wheel' has spread to the neighboring countries in the Mediterranean region."
The tracking is based on components and design principles employed thousands of times in the automotive industry. Basically it is a moving steel structure. The energy supply at the same time should be easy to handle, completely non-sensitive and of course, economical. "As the energy chain is located outdoors largely unprotected, dust, sand, rain and heat should not affect it," says Dipl. Eng. (FH) Gerhard Dirscherl, Development Director. "Then there is a turning mechanism it should cope with in the long term. “
The multidimensionally moving triflex® R energy supply systems in the enclosed model "TRC 70" display their strengths in the photovoltaic plants. They were specially developed by the igus® GmbH, Cologne, for robotic applications and prove themselves here in all solar plants. The tribo-optimized polymer plain bearings from igus® are also used. "We are so confident of our system that we offer a guarantee of 25 years in combination with a maintenance contract. With it, we also provide the required safety for investment funds," clarifies Andreas Fleischmann.
The young company, which belongs to the Josef Rädlinger group of companies, has settled on the premises of a former power plant. There it operates a test facility on the roof of a former site for the desulphurization of exhaust gases at a height of 66 m. Established in July 2006, the first plant in Spain could be already implemented by December 2006. In the meantime four projects with over 300 's:wheel' plants have been implemented all over Spain. A plant consists of a wheel, each with a diameter of 25 m. It is mounted on foundations or pegs. The close-to-the-earth and thereby wind-insensitive system is suited for many module types. For an installed power of 36 kWp, it has higher yields up to 30% than stationary plants.
Whereas the first small photovoltaic plant with a total of 200 kWp installed power went into operation in a Spanish vineyard, the main target clientele is the power plant construction sector. "We build plants of sizes 5 to 8 MW, which means that the plot sizes alone should amount to 80,000 and 150,000 m²," says Andreas Fleischmann. "At present we don't implement any special requirements yet, but still work in the common-part area. However we will further expand our product range to also utilize sunny hillsides, for instance!"
The company looks to the future with more than optimism. Started out with three people, today the location in Schwandorf and headquarters in Cham already employs over 300 people.
... it sets in the west. Every kid learns that in school. In this case, it is an exact course of the sun of 180°. "But this is not quite correct", says Gerhard Dirscherl. "It depends on the season. At the Schwandorf location, for example, in June we have a maximum course of the sun of 240° in azimuth. In the vertical movement, the elevation, we come to a maximum of 60°. Both movements lead to more yield in the plants indeed, but don't pay off the additional costs, so that as a rule we don't move the second axis. “
The one-axis tracking systems can pivot up to a maximum 270°. "Per day we have about 25 switchings. The energy chain moves at a very low speed. The solar lines which lead power from the solar modules are safely protected and guided in it. Depending on how the plant is connected, it is AC or solar or DC power lines," Gerhard Dirscherl explains the system.
The power can be led away only at the rotation center. Here, the "triflex® R" energy chain is stressed the most. Whereas the complete housing remains rigid, the energy chain makes a radial movement with every switching, so that in due course it is increasingly stressed. It is kept in traction at one point with a type of balancer and among other things, doesn't slide too much on the floor, if the plant turns back to its starting position in the night.
The energy supply system consists of 78 individual links and reaches to a length of about 2.50 m. "Due to the secure pivoting area, it is a bit extended," Gerhard Dirscherl explains in retrospect. The high tensile strength and stability are obtained by the so-called "trailer principle", which interconnects the individual elements similar to a towing hitch. The required mobility in all directions is ensured by this ball-shaped formation.
"As a rule we supply the mechanics and the customer contributes to the electrical system," says Andreas Fleischmann. "But if necessary we also undertake the electrical component. In this case, the topic preassembled energy supply systems might become important. For us, that facilitates planning, construction, installation and starting up of the entire plant. But till now we have focused purely on the mechanical component due to capacity reasons. “
The goals of RWenergy stand defined. The entire Mediterranean region is to be tapped bit by bit. The market for renewable energy will continue to grow. "We offer a reliable and maintenance-friendly system. A part thereof are the energy supply systems which prove themselves outdoors. In our view, nothing stands in the way of its further application," Andreas Fleischmann takes stock.