Reliable movement with igubal pillow block bearings in solar trackers

Problem

Each module of the tracker system can consist of units containing 9 or 18 panels of 540 to 560 watts, which have an output of 5 or 10kW. The designers were looking for suitable bearings (two for the 9-panel units, three for the 18-panel units) to support the horizontal square profiles that carry the solar panels. The environment is a challenge for the bearings, as the system is exposed to high temperatures in summer, weather conditions such as wind and rain as well as dirt and dust. Braving these conditions was one of many other requirements placed on the bearings: they have to withstand the high loads of the entire tracking system - consisting of the panels, their supports and a corresponding counterweight - and at the same time have a low coefficient of friction. The bearings should be spherical and capable of absorbing heavy axial loads, allowing for quiet operation without torque fluctuations and featuring a service life of 25 years. All this ideally without lubrication and maintenance.

Solution

The engineers initially considered lubricated metal and composite plain bearings, but then found the technically best and most cost-effective solution at igus: igubal pillow block bearings from the ESTM series, which were specifically developed for single-axis solar tracker systems. They consist of a housing made of igumid G, a particularly robust, long-fibre-reinforced polymer, and a very low-friction iglidur J4 spherical ball. In the igus test laboratory, the service life of the bearings reached 72 years at a load of 1.5 tons, simulated in a time lapse. That is why igus guarantees a service life of 25 years. The cost-effective pillow block bearings are UV-resistant, corrosion-free and require no lubrication, which makes them insensitive to dirt and completely maintenance-free. They also enable self-aligning, e.g. in the case of uneven grounds, and are quick and easy to install thanks to their two-part design. A true "fit and forget" solution that Axiom Research Labs is very happy with.

As part of a demo pilot project, Axiom Research Labs in Pavagada in the Indian state of Karnataka successfully converted around 140kW of an existing system to igubal ESTM bearings.

The bearings are easy to assemble and compensate for misalignments caused by uneven ground, for example.

Successfully tested in the laboratory for resistance to UV radiation and wear, the solar bearings have a guaranteed service life of 25 years.