photovoltaic plant using the triflex R e-chain

Dust, sand, heat and rain

Energy chain for multiaxial movements in photovoltaic plant

The market for photovoltaic plants is booming especially in Mediterranean countries due to the guarantee of virtually unrestricted sunshine. In a patent-pending tracking system for medium to large solar power plants, a multidimensionally moving energy supply system by igus safely guides the solar power lines. Even if they are exposed to extreme wind and weather conditions, a trouble-free operating period far beyond the feed-in period is guaranteed. The service life expectancy of the plants is greater 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, the authorities have now learned a great deal from the construction mistakes of the past," reports Andreas Fleischmann. "With regards 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 6.56 feet. Through the middle of the year, we installed at least 300 s:wheel plants in Spain alone. In the meantime, interest in the patent-pending tracking system's wheel' has spread to the neighboring countries in the Mediterranean region."

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triflex R® 3-dimensional outdoor energy chain

The tracking system 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 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 also a turning mechanism which it should cope with in the long term."

The multidimensionally moving triflex® R energy supply systems in the enclosed model "TRC 70" demonstrate their value in these photovoltaic plants. They were specially developed by the igus® GmbH, Cologne, for robotic applications and prove themselves in solar plants as well. 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.

Triflex energy chain used in photovoltaic plant

Renewable energies on the rise

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 217 ft. 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 82 ft. 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. "Currently, we don't implement any special requirements 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. After starting out with only three employees, the location in Schwandorf and headquarters in Cham currently employ over 300 people.

The power can be led away only at the rotation center. Here, the "triflex® R" energy chain under the most stress. While 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 which keeps it from sliding too much on the floor when the plant turns back to its starting position in the night.

High tensile strength of the energy supply system

The energy supply system consists of 78 individual links and reaches to a length of about 8.2 ft. "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 "trailer principle", which interconnects the individual elements similar to a towing hitch. The required three-dimensional mobility 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 of preassembled energy supply systems might become important. For us, that facilitates planning, construction, installation and starting up of the entire plant. But until now we have focused purely on the mechanical component due to capacity reasons."

The goals of RWenergy are defined as such: 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. Part of which are the energy supply systems which prove themselves outdoors. In our view, nothing stands in the way of its further application," says Andreas Fleischmann.

The sun rises in the east.

It sets in the west. Every kid learns that in school. In this case, it is an exact 180°course of the sun's movement. "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 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, but don't pay off the additional costs. As a rule, we don't move the second axis."

The one-axis tracking systems can pivot up to a maximum 270°. "We have about 25 switchings daily. The energy chain moves at a very low speed. The solar lines which lead power from the solar modules are safely protected and guided inside. Depending on how the plant is connected, it uses either AC or solar or DC power lines," Gerhard Dirscherl explaining the system.