Maintenance-free bearings for Solar tracking systems

Solar tracking systems offer a series of benefits. By automatically following the position of the sun, they perfectly absorb the sun's energy and therefore have a particularly high level of efficiency. This supplier guarantees that the modules in its system remain completely out of the shade.

RWenergy GmbH developed the "s:wheel" single-axis and "s:track" horizontal tilting solar tracking systems to improve energy yield by ensuring optimal alignment with the sun. The "s:wheel" tracks vertically, while the "s:track" tilts horizontally, following the sun's movement from east to west. These systems increase energy production by up to 30% and 15%, respectively, compared to stationary setups. To enhance system longevity and reduce maintenance, the company utilizes igus® self-lubricating plastic bearings in key components.

So that these can work in wind and weather over decades without problems, the company relies on maintenance-free, durable plastic plain bearings.

igus® provided self-lubricating, maintenance-free polymer bearings for both the "s:wheel" and "s:track" systems. In the "s:track," the bearings handle +/- 45° daily tilting movements and are pressed into galvanized steel tubes, maintaining reliability despite installation tolerances. The iglide® G300 material was chosen for its resistance to dust, dirt, and extreme temperatures (-40°F to 266°F), while its robustness allows it to handle high loads and misalignments. The bearings proved ideal for the system’s harsh environments, as endurance tests demonstrated they outlast the plant’s operational life. Moreover, igus®’ triflex® R energy chain system ensures reliable power transmission even under heavy stress and movement.

The systems are not always aligned to the last millimeter. “You have to take tolerances into account in steel constructions,” says Dirscherl. High forces are generated in this case, which the polymer bearings must be able to withstand. Added to that are difficult environmental conditions: accordingly, dust, sand, rain and heat must not have any effects on the functional capability of the overall system. All components must hold their own outdoors over the long term. “Should, for example, the plastic bearing assembly happen to fall onto the dusty ground during assembly, that does not play any part in its functional capability,” says the head of development. “With a sensitive ball bearing assembly, on the other hand, we would experience serious problems by now at the latest."

By using igus® polymer bearings, RWenergy significantly reduced the risk of malfunction during assembly and ensured long-lasting performance, leading to simpler installation and maintenance, especially in challenging environments.

Resistant to dirt and sharp edges

iglide® G300 was chosen as the polymer bearing material. These cost-effective all-round bearings cover a very wide range of applications. They work in dry operations at temperatures of –40 °F to +266 °F. At the same time they are insensitive to dust and dirt, suitable for simple rotational and pivoting movements. The robust bearings also cope with peak and edge loads without problems.

Altogether, 15 iglide® G300 bearings are currently installed in the five steel struts for the north-south axis on the “s:track”. In total there is an available installation space of approx. 100 mm. Due to the high tolerances, three bushings are installed on each strut. “The third bushing basically has no function. It is only installed as a precaution,” says Gerhard Dirscherl. Hence there is the option of inserting a special bearing assembly with a length of 47 mm from left and right as a flange bushing. In this way one bearing can be saved, which further minimizes sources of faults and makes assembly even easier. Dirscherl appears to be very happy with the technical advice, moreover: “The collaboration is good, as can already be seen on the igus® proposal for the special bearing assembly. Although the numbers on new developments can often not be foreseen to start with, we always feel very well looked after."

e-chain for photovoltaic plant
The “s:wheel” solar tracking system for medium and large solar energy plants also uses a multi-dimensionally moving “triflex® R” energy chain system from igus®. This securely guides the solar cables. The power is discharged at the module's rotating center. The plastic energy chain is put under the highest stress at this point. Whereas the complete housing remains rigid, the chain takes a radial movement with every switching, so that it is increasingly stressed with each step. The high tensile strength is 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. In this way a trouble-free operating period can be guaranteed beyond the feed-in period.